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Volume 71 (2022): Issue 3 (September 2022)

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Volume 70 (2021): Issue 3 (September 2021)

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Volume 70 (2021): Issue 1 (March 2021)

Volume 69 (2020): Issue 4 (December 2020)

Volume 69 (2020): Issue 3 (September 2020)

Volume 69 (2020): Issue 2 (June 2020)

Volume 69 (2020): Issue 1 (March 2020)

Volume 68 (2019): Issue 4 (January 2019)

Volume 68 (2019): Issue 3 (September 2019)

Volume 68 (2019): Issue 2 (June 2019)

Volume 68 (2019): Issue 1 (March 2019)

Volume 67 (2018): Issue 4 (December 2018)

Volume 67 (2018): Issue 3 (September 2018)

Volume 67 (2018): Issue 2 (June 2018)

Volume 67 (2018): Issue 1 (January 2018)

Volume 66 (2017): Issue 4 (December 2017)

Volume 66 (2017): Issue 3 (September 2017)

Volume 66 (2017): Issue 2 (June 2017)

Volume 66 (2017): Issue 1 (March 2017)

Volume 65 (2016): Issue 4 (December 2016)

Volume 65 (2016): Issue 3 (August 2016)

Volume 65 (2016): Issue 2 (June 2016)

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Journal Details
Format
Journal
eISSN
2544-4646
First Published
04 Mar 1952
Publication timeframe
4 times per year
Languages
English

Search

Volume 69 (2020): Issue 3 (September 2020)

Journal Details
Format
Journal
eISSN
2544-4646
First Published
04 Mar 1952
Publication timeframe
4 times per year
Languages
English

Search

15 Articles

original-paper

Open Access

Yeasts Associated with Various Amazonian Native Fruits

Published Online: 05 Aug 2020
Page range: 251 - 261

Abstract

Abstract

Yeasts, commonly present on the surface of fruits, are of industrial interest for the production of enzymes, flavorings, and bioactive compounds, and have many other scientific uses. The Amazonian rainforest may be a good source of new species or strains of yeasts, but their presence on Amazonian fruits is unknown. The aim of this study was to identify and characterize yeasts isolated from Amazonian native fruits using molecular and phenotypic methods. In total, 81 yeast isolates were obtained from 10 fruits species. Rep-PCR showed 29 strain profiles. Using a combination of restriction-fragment length polymorphism (RFLP) of the 5.8S-ITS region and D1/D2 sequencing of the 26S rRNA gene, 16 species were identified belonging to genera Candida, Debaryomyces, Hanseniaspora, Kodamaea, Martiniozyma, and Meyerozyma. The most dominant species were Candida tropicalis, Debaryomyces hansenii, Hanseniaspora opuntiae, and Hanseniaspora thailandica. H. opuntiae and H. thailandica showed the highest number of the strain profiles. Phenotypic profiles were variable between species, and even among strains. Screening for hydrolases showed lipolytic activity in only one isolate, while proteolytic, cellulolytic and amylolytic capabilities were not detected. Yeast presence among fruits varied, with cidra (Citrus medica) and ungurahui (Oenocarpus bataua) having the highest number of species associated. This investigation broadens the understanding and possible biotechnological uses of yeast strains obtained from Amazonian native fruits.

Keywords

  • yeast diversity
  • fruit
  • Amazonia
  • PCR-RFLP
  • 5.8S-ITS
Open Access

Molecular Identification and Prevalence of Entamoeba histolytica, Entamoeba dispar and Entamoeba moshkovskii in Erbil City, Northern Iraq

Published Online: 05 Aug 2020
Page range: 263 - 272

Abstract

Abstract

The present study was conducted to evaluate the infection rates of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii among asymptomatic individuals in Erbil City, northern Iraq. The research intent was to discover whether pathogenic or nonpathogenic species cause a high rate of symptomless Entamoeba infections. Stool samples were microscopically examined, and the 18S-rRNA gene was targeted utilizing the nested PCR technique in the positive specimens. Initial results based on morphological features showed that the Entamoeba prevalence rate was 7.4%. Significantly higher rates of infections were seen in females than in males and in low-income people than in moderate-income people. The incidence rates among the asymptomatic individuals, as determined by molecular analysis, were as follows: E. histolytica – 6%, E. dispar – 4.3%, and E. moshkovskii – 0.3%. Of all the Entamoeba positive samples, a single infection with E. histolytica was identified in 41.4% samples; the single infection with E. dispar in 18.6% samples, 35.7% samples had mixed infections with two Entamoeba species, and 4.3% had mixed infections with three species. The current study concluded that 7.4% of healthy people, who live in the endemic area under investigation, carry Entamoeba species asymptomatically. Additionally, the majority of asymptomatic Entamoeba infections were caused by the pathogenic E. histolytica (81.4%) compared to E. dispar (58.6%), and E. moshkovskii with the lowest rate of infection. Single and co-infections with E. histolytica and E. dispar were noted. E. moshkovskii, which was identified for the first time in the region, was only seen in mixed infections.

Keywords

  • epidemiology
  • asymptomatic infections
Open Access

Improved Biosurfactant Production by Enterobacter cloacae B14, Stability Studies, and its Antimicrobial Activity

Published Online: 14 Aug 2020
Page range: 273 - 282

Abstract

Abstract

This work aimed to optimize carbon and nitrogen sources for the growth of Enterobacter cloacae B14 and its biosurfactant (BS) production via One-Variable-At-a-Time (OVAT) method. The BS stability under a range of pH and temperatures was assessed. Antimicrobial activity against Gram-positive and Gram-negative pathogens was determined by the agar well diffusion method. The results showed that the optimum carbon and nitrogen sources for BS production were maltose and yeast extract, respectively, with a maximum BS yield of (39.8 ± 5.2) mg BS/g biomass. The highest emulsification activity (E24) was 79%, which is significantly higher than in the previous studies. We found that B14 BS can withstand a wide range of pH values from 2 to10. It could also function under a range of temperatures from 30–37°C. Thin Layer Chromatography (TLC) and Fourier Transform Infrared Spectrometry (FTIR) analysis confirmed that B14 BS is a glycolipid-like compound, which is rarely found in Enterobacter spp. Cell-free broth showed inhibition against various pathogens, preferable to Gram-positive ones. It had better antimicrobial activity against Bacillus subtilis than a commonly-used antibiotic, tetracycline. Furthermore, B14 broth could inhibit the growth of a tetracycline-resistant Serratia marcescens. Our results showed promising B14 BS applications not only for bioremediation but also for the production of antimicrobial products.

Keywords

  • biosurfactant
  • cultivation media
  • antimicrobial activity
  • stability
Open Access

Characteristics and Diversity of Endophytic Bacteria in Endangered Chinese Herb Glehnia littoralis Based on Illumina Sequencing

Published Online: 08 Sep 2020
Page range: 283 - 291

Abstract

Abstract

Glehnia littoralis is an endangered medicinal plant growing in the coastal ecological environment and plays an important role in coastal ecosystems. The endophytes in the plant have a significant role in promoting plant growth and enhancing plant stress resistance. However, the endophytic bacterial structure associated with halophyte G. littoralis is still not revealed. In this project, the construction and diversity of endophytic bacterial consortium associated with different tissues of G. littoralis were illustrated with high throughput sequencing of the V3-V4 region of the bacterial 16S rRNA. The results resolved that the diversity and richness of endophytic bacteria were significantly higher in root than in leaf and stem. The operational taxonomic units (OTU) analysis demonstrated that the Actinobacteria and Proteobacteria were dominant in all the samples at the phylum level, and Pseudomonas, Bacillus, Rhizobium were the dominant genera. Our results unraveled that the bacterial communities differed among different tissues of G. littoralis. Endophytic bacterial communities in leaf and stem shared more similarity than that in the root. Furthermore, the difference of bacteria community and structure among different tissues were also detected by principal coordinate analysis. Taken altogether, we can conclude that the bacterial communities of different tissues are unique, which could facilitate understanding the diversity of endophytic bacteria in G. littoralis.

Keywords

  • halophyte
  • endophytic bacteria
  • diversity
  • Illumina sequencing
Open Access

Establishment and Application of a Dual TaqMan Real-Time PCR Method for Proteus Mirabilis and Proteus Vulgaris

Published Online: 25 Aug 2020
Page range: 293 - 300

Abstract

Abstract

Proteus species are common opportunistic bacteria and foodborne pathogens. The proper detection of Proteus can effectively reduce the occurrence of food-borne public health events. Proteus mirabilis and Proteus vulgaris are the two most important pathogens in the Proteus genus. In this study, a dual TaqMan Real-Time PCR method was established to simultaneously detect and distinguish P. mirabilis and P. vulgaris in samples. The method exhibited good specificity, stability, and sensitivity. Specifically, the minimum detection concentrations of P. mirabilis and P. vulgaris in pure bacterial cultures were 6.08 × 102 colony forming units (CFU)/ml and 4.46 × 102 CFU/ml, respectively. Additionally, the minimum detectable number of P. mirabilis and P. vulgaris in meat and milk was 103 CFU/g. In addition, the method can be used to distinguish between strains of P. mirabilis and P. vulgaris within two hours. Overall, it is a sensitive, easy-to-use, and practical test for the identification and classification of Proteus in food.

Keywords

  • TaqMan Real-Time PCR
  • food-borne pathogens
  • food poisoning
Open Access

The Effect of Environmental Stresses on lipL32 Gene Expression in Pathogenic Leptospira spp. through Real-Time PCR

Published Online: 08 Sep 2020
Page range: 301 - 310

Abstract

Abstract

Leptospirosis is a worldwide infectious and zoonotic disease. The incidence of this disease is high in temperate regions, especially in northern Iran. The aim of this study was to investigate the effects of temperature, pH, and Phyllanthus amarus plant extract on the lipL32 gene expression in pathogenic Leptospira spp. Fifty water samples were collected. Culture and PCR technique were used to isolate and identify the bacterium and the presence of the lipL32 gene. The samples were exposed to different temperatures and pH levels for one day and the Ph. amarus plant extract at different concentrations for one and seven days. RNA was extracted, and cDNA synthesis was performed for all the samples. All cDNAs were evaluated by the real-time PCR (SYBR green) technique. Out of the 50 samples, ten samples (20%), using PCR were determined to contain the pathogenic Leptospira. Fold change of the expression of the lipL32 gene associated with stresses was as follows: temperature stress of 40°C, 35°C, and 25°C reduced the lipL32 gene expression in all three isolates, especially in the isolates type 1. The pH stress, i.e., pH values equal to 8 or 9 reduced the gene expression in three types of isolates, and pH = 6 stress increases the lipL32 gene expression in the isolates of type 1. Ph. amarus plant extract stress reduced the mentioned gene expression only in isolates of type 2. Temperature and pH stresses could lead to differences in the expression level and cause the lipL32 gene expression decrease in three pathogenic isolates. The MIC results showed anti-leptospiral effect of Ph. amarus plant extract.

Keywords

  • gene expression
  • real-time PCR
  • stress
Open Access

A Polyclonal Spread Emerged: Characteristics of Carbapenem-Resistant Klebsiella pneumoniae Isolates from the Intensive Care Unit in a Chinese Tertiary Hospital

Published Online: 08 Sep 2020
Page range: 311 - 319

Abstract

Abstract

Carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates often cause nosocomial infections with limited therapeutic options and spread rapidly worldwide. In this study, we revealed a polyclonal emergence of CRKP isolates from the intensive care unit in a Chinese tertiary hospital. We applied a series of methods including automated screening, antimicrobial susceptibility testing, the modified carbapenem inacti vation method (mCIM), PCR amplification, DNA sequencing, and multilocus sequence typing (MLST) to characterize 30 non-duplicated CRKP isolates along with the collection of the related medical records. The results showed the polyclonal spread of CRKP isolates belonged to ST722, ST1446, ST111, ST896, ST290, and ST11. Among them, ST722 and ST1446 were two novel types of K. pneumoniae, and ST896 isolate harboring blaKPC-2 was also found for the first time. Since the polyclonal spread of CRKP in the same ward is rare, the silent clonal evolution with the switching genotypes prompts us to stay alert for outbreaks caused by novel subclones.

Keywords

  • polyclonal spread
  • carbapenem-resistant
  • sequence type
  • intensive care unit
  • alert
Open Access

Marine Sediment Recovered Salinispora sp. Inhibits the Growth of Emerging Bacterial Pathogens and other Multi-Drug-Resistant Bacteria

Published Online: 08 Sep 2020
Page range: 321 - 330

Abstract

Abstract

Marine obligate actinobacteria produce a wide variety of secondary metabolites with biological activity, notably those with antibiotic activity urgently needed against multi-drug-resistant bacteria. Seventy-five marine actinobacteria were isolated from a marine sediment sample collected in Punta Arena de La Ventana, Baja California Sur, Mexico. The 16S rRNA gene identification, Multi Locus Sequence Analysis, and the marine salt requirement for growth assigned seventy-one isolates as members of the genus Salinispora, grouped apart but related to the main Salinispora arenicola species clade. The ability of salinisporae to inhibit bacterial growth of Staphylococcus epidermidis, Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacer baumannii, Pseudomonas aeruginosa, and Enterobacter spp. was evaluated by cross-streaking plate and supernatant inhibition tests. Ten supernatants inhibited the growth of eight strains of S. epidermidis from patients suffering from ocular infections, two out of the eight showed growth inhibition on ten S. epidermidis strains from prosthetic joint infections. Also, it inhibited the growth of the remaining six multi-drug-resistant bacteria tested. These results showed that some Salinispora strains could produce antibacterial compounds to combat bacteria of clinical importance and prove that studying different geographical sites uncovers untapped microorganisms with metabolic potential.

Keywords

  • multi-drug-resistant bacteria
  • MLSA
  • Punta Arena de la Ventana
Open Access

Determining Risk Factors for Dengue Fever Severity in Jeddah City, a Case-Control Study (2017)

Published Online: 26 Aug 2020
Page range: 331 - 337

Abstract

Abstract

Dengue fever is a major public health problem in Saudi Arabia. Unfortunately, preventive strategies are still deficient. It can progress to severe and lethal forms, and available knowledge does not allow early prediction of which cases of dengue fever (DF) will progress to dengue hemorrhagic fever (DHF). The aim of this study was to evaluate the host and viral factors that could play a role in the progression of severe dengue cases in the frame of the revised 2009 WHO classification. Data were compiled from the Jeddah Dengue Fever Operation Room (DFOR) in the Maden Al-Fahd primary healthcare center in Jeddah. An unmatched case-control study was conducted on 123 severe cases, and 245 controls (non-severe cases) diagnosed during 2014–2016. Risk factors for severe dengue fever were secondary infection (p = 0.02), and co-morbidities, particularly diabetes and hypertension (p < 0.001). Age, gender, nationality, socioeconomic status, viral serotype, and access to health care were not significantly associated with severe disease. The main risk factors for severe dengue fever were secondary infection, and co-morbidities (hypertension and diabetes). We recommend disseminating these data to stakeholders to improve dengue control interventions in periods with anticipated high incidence.

Keywords

  • Dengue fever
  • viral infection
  • case control
  • risk factors
Open Access

Characterization of Ligninolytic Bacteria and Analysis of Alkali-Lignin Biodegradation Products

Published Online: 09 Sep 2020
Page range: 339 - 347

Abstract

Abstract

Ligninolytic bacteria degrading lignin were isolates and identified, and their biodegradation mechanism of alkaline-lignin was investigated. Four strains with lignin degradation capability were screened and identified from the soil, straw, and silage based on their decolorizing capacity of aniline blue and colony size on alkaline-lignin medium. The degradation ratio of Bacillus aryabhattai BY5, Acinetobacter johnsonii LN2, Acinetobacter lwoffii LN4, and Micrococcus yunnanensis CL32 have been assayed using alkaline-lignin as the unique carbon source. Further, the Lip (lignin peroxidase) and Mnp (manganese peroxidase) activities of strains were investigated. Lip activity of A. lwoffii LN4 was highest after 72 h of incubation and reached 7151.7 U · l–1. Mnp activity of M. yunnanensis CL32 was highest after 48 h and reached 12533 U · l–1. The analysis of alkaline-lignin degradation products by GC-MS revealed that the strains screened could utilize aromatic esters compounds such as dibutyl phthalate (DBP), and decomposite monocyclic aromatic compounds through the DBP aerobic metabolic pathway. The results indicate that B. aryabhattai BY5, A. johnsonii LN2, A. lwoffii LN4, and M. yunnanensis CL32 have high potential to degrade alkaline-lignin, and might utilize aromatic compounds by DBP aerobic metabolic pathway in the process of lignin degradation.

Keywords

  • isolation
  • bacteria
  • alkali-lignin
  • biodegradation products
Open Access

Characterization of Two Macrolide Resistance-Related Genes in Multidrug-Resistant Pseudomonas aeruginosa Isolates

Published Online: 08 Sep 2020
Page range: 349 - 356

Abstract

Abstract

In analyzing the drug resistance phenotype and mechanism of resistance to macrolide antibiotics of clinical Pseudomonas aeruginosa isolates, the agar dilution method was used to determine the minimum inhibitory concentrations (MICs), and PCR (polymerase chain reaction) was applied to screen for macrolide antibiotics resistance genes. The macrolide antibiotics resistance genes were cloned, and their functions were identified. Of the 13 antibiotics tested, P. aeruginosa strains showed high resistance rates (ranging from 69.5–82.1%), and MIC levels (MIC90 > 256 μg/ml) to macrolide antibiotics. Of the 131 known macrolide resistance genes, only two genes, mphE and msrE, were identified in 262 clinical P. aeruginosa isolates. Four strains (1.53%, 4/262) carried both the msrE and mphE genes, and an additional three strains (1.15%, 3/262) harbored the mphE gene alone. The cloned msrE and mphE genes conferred higher resistance levels to three second-generation macrolides compared to two first-generation ones. Analysis of MsrE and MphE protein polymorphisms revealed that they are highly conserved, with only 1–3 amino acids differences between the proteins of the same type. It can be concluded that even though the strains showed high resistance levels to macrolides, known macrolide resistance genes are seldom present in clinical P. aeruginosa strains, demonstrating that a mechanism other than this warranted by the mphE and msrE genes may play a more critical role in the bacteria’s resistance to macrolides.

Keywords

  • macrolide
  • resistance gene
Open Access

Isolated Phosphate-Solubilizing Soil Bacteria Promotes In vitro Growth of Solanum tuberosum L.

Published Online: 08 Sep 2020
Page range: 357 - 365

Abstract

Abstract

The capacity of four bacterial strains isolated from productive soil potato fields to solubilize tricalcium phosphate on Pikovskaya agar or in a liquid medium was evaluated. A bacterial strain was selected to evaluate in vitro capacity of plant-growth promotion on Solanum tuberosum L. culture. Bacterial strain A3 showed the highest value of phosphate solubilization, reaching a 20 mm-diameter halo and a concentration of 350 mg/l on agar and in a liquid medium, respectively. Bacterial strain A3 was identified by 16S rDNA analysis as Bacillus pumilus with 98% identity; therefore, it is the first report for Bacillus pumilus as phosphate solubilizer. Plant-growth promotion assayed by in vitro culture of potato microplants showed that the addition of bacterial strain A3 increased root and stems length after 28 days. It significantly increased stem length by 79.3%, and duplicated the fresh weight of control microplants. In this paper, results reported regarding phosphorus solubilization and growth promotion under in vitro conditions represent a step forward in the use of innocuous bacterial strain biofertilizer on potato field cultures.

Keywords

  • sp.
  • phosphorus soluble
  • Pikovskaya agar
  • potato rhizosphere
  • plant growth promoting rhizobacteria
Open Access

Characteristics of the Jejunal Microbiota in 35-Day-Old Saba and Landrace Piglets

Published Online: 08 Sep 2020
Page range: 367 - 378

Abstract

Abstract

The balanced microbiological system is a significant hallmark of piglet health. One of the crucial factors affecting intestinal microbiota is the host’s genetics. This study explored the difference in the diversity of jejunal microbiota between Saba (SB) and Landrace (LA) piglets. Nine Saba and nine Landrace piglets were fed with sow’s milk until day 35. Jejunal contents were harvested for 16S rRNA sequencing. The birth weight, body weight, and average daily gain of Saba piglets were lower than those of Landrace piglets (p < 0.01). Firmicutes were the main phylum in Saba and Landrace piglets, and the Saba piglets had a higher (p < 0.05) abundance of Bacteroidetes compared with Landrace piglets. The two most abundant genera were Lactobacilli and Clostridium XI in the jejunum of Landrace and Saba piglets. Compared with Landrace piglets, the Saba piglets had significantly lower (p < 0.05) abundance of Veillonella, Streptococcus, and Saccharibacteria genera incertae sedis. The functional prediction showed that “d-glutamine and d-glutamate metabolism” and “one carbon pool by folate” pathways were enriched in Saba piglets, while “limonene and pinene degradation”, “tryptophan metabolism”, and “sulfur relay system” pathways were enriched in Landrace piglets. In summary, the growth performance was higher for Landrace piglets compared with Saba piglets due to their genetic characteristics. The rich diversity and fewer infection-associated taxa were observed in Saba piglets, partially accounting for their higher adaptability to environmental perturbations than Landrace piglets. Furthermore, different pig breeds may regulate their health through different metabolic pathways.

Keywords

  • Saba piglets
  • Landrace piglets
  • jejunal content
  • the 16S rRNA gene
  • diversity

short-communication

Open Access

In vitro Antagonistic Activity of Endophytic Fungi Isolated from Shirazi Thyme (Zataria multiflora Boiss.) against Monosporascus cannonballus

Published Online: 05 Aug 2020
Page range: 379 - 383

Abstract

Abstract

Endophytic fungi viz., Nigrospora sphaerica (E1 and E6), Subramaniula cristata (E7), and Polycephalomyces sinensis (E8 and E10) were isolated from the medicinal plant, Shirazi thyme (Zataria multiflora). In in vitro tests, these endophytes inhibited the mycelial growth of Monosporascus cannonballus, a plant pathogenic fungus. Morphological abnormalities in the hyphae of M. cannonballus at the edge of the inhibition zone in dual cultures with N. sphaerica were observed. The culture filtrates of these endophytes caused leakage of electrolytes from the mycelium of M. cannonballus. To our knowledge, this is the first report on the isolation and characterization of fungal endophytes from Z. multiflora as well as their antifungal effect on M. cannonballus.

Keywords

  • antifungal
  • endophytic fungi

non-scientific

Open Access

Memorial Tribute

Published Online: 08 Sep 2020
Page range: 249 - 249

Abstract

15 Articles

original-paper

Open Access

Yeasts Associated with Various Amazonian Native Fruits

Published Online: 05 Aug 2020
Page range: 251 - 261

Abstract

Abstract

Yeasts, commonly present on the surface of fruits, are of industrial interest for the production of enzymes, flavorings, and bioactive compounds, and have many other scientific uses. The Amazonian rainforest may be a good source of new species or strains of yeasts, but their presence on Amazonian fruits is unknown. The aim of this study was to identify and characterize yeasts isolated from Amazonian native fruits using molecular and phenotypic methods. In total, 81 yeast isolates were obtained from 10 fruits species. Rep-PCR showed 29 strain profiles. Using a combination of restriction-fragment length polymorphism (RFLP) of the 5.8S-ITS region and D1/D2 sequencing of the 26S rRNA gene, 16 species were identified belonging to genera Candida, Debaryomyces, Hanseniaspora, Kodamaea, Martiniozyma, and Meyerozyma. The most dominant species were Candida tropicalis, Debaryomyces hansenii, Hanseniaspora opuntiae, and Hanseniaspora thailandica. H. opuntiae and H. thailandica showed the highest number of the strain profiles. Phenotypic profiles were variable between species, and even among strains. Screening for hydrolases showed lipolytic activity in only one isolate, while proteolytic, cellulolytic and amylolytic capabilities were not detected. Yeast presence among fruits varied, with cidra (Citrus medica) and ungurahui (Oenocarpus bataua) having the highest number of species associated. This investigation broadens the understanding and possible biotechnological uses of yeast strains obtained from Amazonian native fruits.

Keywords

  • yeast diversity
  • fruit
  • Amazonia
  • PCR-RFLP
  • 5.8S-ITS
Open Access

Molecular Identification and Prevalence of Entamoeba histolytica, Entamoeba dispar and Entamoeba moshkovskii in Erbil City, Northern Iraq

Published Online: 05 Aug 2020
Page range: 263 - 272

Abstract

Abstract

The present study was conducted to evaluate the infection rates of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii among asymptomatic individuals in Erbil City, northern Iraq. The research intent was to discover whether pathogenic or nonpathogenic species cause a high rate of symptomless Entamoeba infections. Stool samples were microscopically examined, and the 18S-rRNA gene was targeted utilizing the nested PCR technique in the positive specimens. Initial results based on morphological features showed that the Entamoeba prevalence rate was 7.4%. Significantly higher rates of infections were seen in females than in males and in low-income people than in moderate-income people. The incidence rates among the asymptomatic individuals, as determined by molecular analysis, were as follows: E. histolytica – 6%, E. dispar – 4.3%, and E. moshkovskii – 0.3%. Of all the Entamoeba positive samples, a single infection with E. histolytica was identified in 41.4% samples; the single infection with E. dispar in 18.6% samples, 35.7% samples had mixed infections with two Entamoeba species, and 4.3% had mixed infections with three species. The current study concluded that 7.4% of healthy people, who live in the endemic area under investigation, carry Entamoeba species asymptomatically. Additionally, the majority of asymptomatic Entamoeba infections were caused by the pathogenic E. histolytica (81.4%) compared to E. dispar (58.6%), and E. moshkovskii with the lowest rate of infection. Single and co-infections with E. histolytica and E. dispar were noted. E. moshkovskii, which was identified for the first time in the region, was only seen in mixed infections.

Keywords

  • epidemiology
  • asymptomatic infections
Open Access

Improved Biosurfactant Production by Enterobacter cloacae B14, Stability Studies, and its Antimicrobial Activity

Published Online: 14 Aug 2020
Page range: 273 - 282

Abstract

Abstract

This work aimed to optimize carbon and nitrogen sources for the growth of Enterobacter cloacae B14 and its biosurfactant (BS) production via One-Variable-At-a-Time (OVAT) method. The BS stability under a range of pH and temperatures was assessed. Antimicrobial activity against Gram-positive and Gram-negative pathogens was determined by the agar well diffusion method. The results showed that the optimum carbon and nitrogen sources for BS production were maltose and yeast extract, respectively, with a maximum BS yield of (39.8 ± 5.2) mg BS/g biomass. The highest emulsification activity (E24) was 79%, which is significantly higher than in the previous studies. We found that B14 BS can withstand a wide range of pH values from 2 to10. It could also function under a range of temperatures from 30–37°C. Thin Layer Chromatography (TLC) and Fourier Transform Infrared Spectrometry (FTIR) analysis confirmed that B14 BS is a glycolipid-like compound, which is rarely found in Enterobacter spp. Cell-free broth showed inhibition against various pathogens, preferable to Gram-positive ones. It had better antimicrobial activity against Bacillus subtilis than a commonly-used antibiotic, tetracycline. Furthermore, B14 broth could inhibit the growth of a tetracycline-resistant Serratia marcescens. Our results showed promising B14 BS applications not only for bioremediation but also for the production of antimicrobial products.

Keywords

  • biosurfactant
  • cultivation media
  • antimicrobial activity
  • stability
Open Access

Characteristics and Diversity of Endophytic Bacteria in Endangered Chinese Herb Glehnia littoralis Based on Illumina Sequencing

Published Online: 08 Sep 2020
Page range: 283 - 291

Abstract

Abstract

Glehnia littoralis is an endangered medicinal plant growing in the coastal ecological environment and plays an important role in coastal ecosystems. The endophytes in the plant have a significant role in promoting plant growth and enhancing plant stress resistance. However, the endophytic bacterial structure associated with halophyte G. littoralis is still not revealed. In this project, the construction and diversity of endophytic bacterial consortium associated with different tissues of G. littoralis were illustrated with high throughput sequencing of the V3-V4 region of the bacterial 16S rRNA. The results resolved that the diversity and richness of endophytic bacteria were significantly higher in root than in leaf and stem. The operational taxonomic units (OTU) analysis demonstrated that the Actinobacteria and Proteobacteria were dominant in all the samples at the phylum level, and Pseudomonas, Bacillus, Rhizobium were the dominant genera. Our results unraveled that the bacterial communities differed among different tissues of G. littoralis. Endophytic bacterial communities in leaf and stem shared more similarity than that in the root. Furthermore, the difference of bacteria community and structure among different tissues were also detected by principal coordinate analysis. Taken altogether, we can conclude that the bacterial communities of different tissues are unique, which could facilitate understanding the diversity of endophytic bacteria in G. littoralis.

Keywords

  • halophyte
  • endophytic bacteria
  • diversity
  • Illumina sequencing
Open Access

Establishment and Application of a Dual TaqMan Real-Time PCR Method for Proteus Mirabilis and Proteus Vulgaris

Published Online: 25 Aug 2020
Page range: 293 - 300

Abstract

Abstract

Proteus species are common opportunistic bacteria and foodborne pathogens. The proper detection of Proteus can effectively reduce the occurrence of food-borne public health events. Proteus mirabilis and Proteus vulgaris are the two most important pathogens in the Proteus genus. In this study, a dual TaqMan Real-Time PCR method was established to simultaneously detect and distinguish P. mirabilis and P. vulgaris in samples. The method exhibited good specificity, stability, and sensitivity. Specifically, the minimum detection concentrations of P. mirabilis and P. vulgaris in pure bacterial cultures were 6.08 × 102 colony forming units (CFU)/ml and 4.46 × 102 CFU/ml, respectively. Additionally, the minimum detectable number of P. mirabilis and P. vulgaris in meat and milk was 103 CFU/g. In addition, the method can be used to distinguish between strains of P. mirabilis and P. vulgaris within two hours. Overall, it is a sensitive, easy-to-use, and practical test for the identification and classification of Proteus in food.

Keywords

  • TaqMan Real-Time PCR
  • food-borne pathogens
  • food poisoning
Open Access

The Effect of Environmental Stresses on lipL32 Gene Expression in Pathogenic Leptospira spp. through Real-Time PCR

Published Online: 08 Sep 2020
Page range: 301 - 310

Abstract

Abstract

Leptospirosis is a worldwide infectious and zoonotic disease. The incidence of this disease is high in temperate regions, especially in northern Iran. The aim of this study was to investigate the effects of temperature, pH, and Phyllanthus amarus plant extract on the lipL32 gene expression in pathogenic Leptospira spp. Fifty water samples were collected. Culture and PCR technique were used to isolate and identify the bacterium and the presence of the lipL32 gene. The samples were exposed to different temperatures and pH levels for one day and the Ph. amarus plant extract at different concentrations for one and seven days. RNA was extracted, and cDNA synthesis was performed for all the samples. All cDNAs were evaluated by the real-time PCR (SYBR green) technique. Out of the 50 samples, ten samples (20%), using PCR were determined to contain the pathogenic Leptospira. Fold change of the expression of the lipL32 gene associated with stresses was as follows: temperature stress of 40°C, 35°C, and 25°C reduced the lipL32 gene expression in all three isolates, especially in the isolates type 1. The pH stress, i.e., pH values equal to 8 or 9 reduced the gene expression in three types of isolates, and pH = 6 stress increases the lipL32 gene expression in the isolates of type 1. Ph. amarus plant extract stress reduced the mentioned gene expression only in isolates of type 2. Temperature and pH stresses could lead to differences in the expression level and cause the lipL32 gene expression decrease in three pathogenic isolates. The MIC results showed anti-leptospiral effect of Ph. amarus plant extract.

Keywords

  • gene expression
  • real-time PCR
  • stress
Open Access

A Polyclonal Spread Emerged: Characteristics of Carbapenem-Resistant Klebsiella pneumoniae Isolates from the Intensive Care Unit in a Chinese Tertiary Hospital

Published Online: 08 Sep 2020
Page range: 311 - 319

Abstract

Abstract

Carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates often cause nosocomial infections with limited therapeutic options and spread rapidly worldwide. In this study, we revealed a polyclonal emergence of CRKP isolates from the intensive care unit in a Chinese tertiary hospital. We applied a series of methods including automated screening, antimicrobial susceptibility testing, the modified carbapenem inacti vation method (mCIM), PCR amplification, DNA sequencing, and multilocus sequence typing (MLST) to characterize 30 non-duplicated CRKP isolates along with the collection of the related medical records. The results showed the polyclonal spread of CRKP isolates belonged to ST722, ST1446, ST111, ST896, ST290, and ST11. Among them, ST722 and ST1446 were two novel types of K. pneumoniae, and ST896 isolate harboring blaKPC-2 was also found for the first time. Since the polyclonal spread of CRKP in the same ward is rare, the silent clonal evolution with the switching genotypes prompts us to stay alert for outbreaks caused by novel subclones.

Keywords

  • polyclonal spread
  • carbapenem-resistant
  • sequence type
  • intensive care unit
  • alert
Open Access

Marine Sediment Recovered Salinispora sp. Inhibits the Growth of Emerging Bacterial Pathogens and other Multi-Drug-Resistant Bacteria

Published Online: 08 Sep 2020
Page range: 321 - 330

Abstract

Abstract

Marine obligate actinobacteria produce a wide variety of secondary metabolites with biological activity, notably those with antibiotic activity urgently needed against multi-drug-resistant bacteria. Seventy-five marine actinobacteria were isolated from a marine sediment sample collected in Punta Arena de La Ventana, Baja California Sur, Mexico. The 16S rRNA gene identification, Multi Locus Sequence Analysis, and the marine salt requirement for growth assigned seventy-one isolates as members of the genus Salinispora, grouped apart but related to the main Salinispora arenicola species clade. The ability of salinisporae to inhibit bacterial growth of Staphylococcus epidermidis, Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacer baumannii, Pseudomonas aeruginosa, and Enterobacter spp. was evaluated by cross-streaking plate and supernatant inhibition tests. Ten supernatants inhibited the growth of eight strains of S. epidermidis from patients suffering from ocular infections, two out of the eight showed growth inhibition on ten S. epidermidis strains from prosthetic joint infections. Also, it inhibited the growth of the remaining six multi-drug-resistant bacteria tested. These results showed that some Salinispora strains could produce antibacterial compounds to combat bacteria of clinical importance and prove that studying different geographical sites uncovers untapped microorganisms with metabolic potential.

Keywords

  • multi-drug-resistant bacteria
  • MLSA
  • Punta Arena de la Ventana
Open Access

Determining Risk Factors for Dengue Fever Severity in Jeddah City, a Case-Control Study (2017)

Published Online: 26 Aug 2020
Page range: 331 - 337

Abstract

Abstract

Dengue fever is a major public health problem in Saudi Arabia. Unfortunately, preventive strategies are still deficient. It can progress to severe and lethal forms, and available knowledge does not allow early prediction of which cases of dengue fever (DF) will progress to dengue hemorrhagic fever (DHF). The aim of this study was to evaluate the host and viral factors that could play a role in the progression of severe dengue cases in the frame of the revised 2009 WHO classification. Data were compiled from the Jeddah Dengue Fever Operation Room (DFOR) in the Maden Al-Fahd primary healthcare center in Jeddah. An unmatched case-control study was conducted on 123 severe cases, and 245 controls (non-severe cases) diagnosed during 2014–2016. Risk factors for severe dengue fever were secondary infection (p = 0.02), and co-morbidities, particularly diabetes and hypertension (p < 0.001). Age, gender, nationality, socioeconomic status, viral serotype, and access to health care were not significantly associated with severe disease. The main risk factors for severe dengue fever were secondary infection, and co-morbidities (hypertension and diabetes). We recommend disseminating these data to stakeholders to improve dengue control interventions in periods with anticipated high incidence.

Keywords

  • Dengue fever
  • viral infection
  • case control
  • risk factors
Open Access

Characterization of Ligninolytic Bacteria and Analysis of Alkali-Lignin Biodegradation Products

Published Online: 09 Sep 2020
Page range: 339 - 347

Abstract

Abstract

Ligninolytic bacteria degrading lignin were isolates and identified, and their biodegradation mechanism of alkaline-lignin was investigated. Four strains with lignin degradation capability were screened and identified from the soil, straw, and silage based on their decolorizing capacity of aniline blue and colony size on alkaline-lignin medium. The degradation ratio of Bacillus aryabhattai BY5, Acinetobacter johnsonii LN2, Acinetobacter lwoffii LN4, and Micrococcus yunnanensis CL32 have been assayed using alkaline-lignin as the unique carbon source. Further, the Lip (lignin peroxidase) and Mnp (manganese peroxidase) activities of strains were investigated. Lip activity of A. lwoffii LN4 was highest after 72 h of incubation and reached 7151.7 U · l–1. Mnp activity of M. yunnanensis CL32 was highest after 48 h and reached 12533 U · l–1. The analysis of alkaline-lignin degradation products by GC-MS revealed that the strains screened could utilize aromatic esters compounds such as dibutyl phthalate (DBP), and decomposite monocyclic aromatic compounds through the DBP aerobic metabolic pathway. The results indicate that B. aryabhattai BY5, A. johnsonii LN2, A. lwoffii LN4, and M. yunnanensis CL32 have high potential to degrade alkaline-lignin, and might utilize aromatic compounds by DBP aerobic metabolic pathway in the process of lignin degradation.

Keywords

  • isolation
  • bacteria
  • alkali-lignin
  • biodegradation products
Open Access

Characterization of Two Macrolide Resistance-Related Genes in Multidrug-Resistant Pseudomonas aeruginosa Isolates

Published Online: 08 Sep 2020
Page range: 349 - 356

Abstract

Abstract

In analyzing the drug resistance phenotype and mechanism of resistance to macrolide antibiotics of clinical Pseudomonas aeruginosa isolates, the agar dilution method was used to determine the minimum inhibitory concentrations (MICs), and PCR (polymerase chain reaction) was applied to screen for macrolide antibiotics resistance genes. The macrolide antibiotics resistance genes were cloned, and their functions were identified. Of the 13 antibiotics tested, P. aeruginosa strains showed high resistance rates (ranging from 69.5–82.1%), and MIC levels (MIC90 > 256 μg/ml) to macrolide antibiotics. Of the 131 known macrolide resistance genes, only two genes, mphE and msrE, were identified in 262 clinical P. aeruginosa isolates. Four strains (1.53%, 4/262) carried both the msrE and mphE genes, and an additional three strains (1.15%, 3/262) harbored the mphE gene alone. The cloned msrE and mphE genes conferred higher resistance levels to three second-generation macrolides compared to two first-generation ones. Analysis of MsrE and MphE protein polymorphisms revealed that they are highly conserved, with only 1–3 amino acids differences between the proteins of the same type. It can be concluded that even though the strains showed high resistance levels to macrolides, known macrolide resistance genes are seldom present in clinical P. aeruginosa strains, demonstrating that a mechanism other than this warranted by the mphE and msrE genes may play a more critical role in the bacteria’s resistance to macrolides.

Keywords

  • macrolide
  • resistance gene
Open Access

Isolated Phosphate-Solubilizing Soil Bacteria Promotes In vitro Growth of Solanum tuberosum L.

Published Online: 08 Sep 2020
Page range: 357 - 365

Abstract

Abstract

The capacity of four bacterial strains isolated from productive soil potato fields to solubilize tricalcium phosphate on Pikovskaya agar or in a liquid medium was evaluated. A bacterial strain was selected to evaluate in vitro capacity of plant-growth promotion on Solanum tuberosum L. culture. Bacterial strain A3 showed the highest value of phosphate solubilization, reaching a 20 mm-diameter halo and a concentration of 350 mg/l on agar and in a liquid medium, respectively. Bacterial strain A3 was identified by 16S rDNA analysis as Bacillus pumilus with 98% identity; therefore, it is the first report for Bacillus pumilus as phosphate solubilizer. Plant-growth promotion assayed by in vitro culture of potato microplants showed that the addition of bacterial strain A3 increased root and stems length after 28 days. It significantly increased stem length by 79.3%, and duplicated the fresh weight of control microplants. In this paper, results reported regarding phosphorus solubilization and growth promotion under in vitro conditions represent a step forward in the use of innocuous bacterial strain biofertilizer on potato field cultures.

Keywords

  • sp.
  • phosphorus soluble
  • Pikovskaya agar
  • potato rhizosphere
  • plant growth promoting rhizobacteria
Open Access

Characteristics of the Jejunal Microbiota in 35-Day-Old Saba and Landrace Piglets

Published Online: 08 Sep 2020
Page range: 367 - 378

Abstract

Abstract

The balanced microbiological system is a significant hallmark of piglet health. One of the crucial factors affecting intestinal microbiota is the host’s genetics. This study explored the difference in the diversity of jejunal microbiota between Saba (SB) and Landrace (LA) piglets. Nine Saba and nine Landrace piglets were fed with sow’s milk until day 35. Jejunal contents were harvested for 16S rRNA sequencing. The birth weight, body weight, and average daily gain of Saba piglets were lower than those of Landrace piglets (p < 0.01). Firmicutes were the main phylum in Saba and Landrace piglets, and the Saba piglets had a higher (p < 0.05) abundance of Bacteroidetes compared with Landrace piglets. The two most abundant genera were Lactobacilli and Clostridium XI in the jejunum of Landrace and Saba piglets. Compared with Landrace piglets, the Saba piglets had significantly lower (p < 0.05) abundance of Veillonella, Streptococcus, and Saccharibacteria genera incertae sedis. The functional prediction showed that “d-glutamine and d-glutamate metabolism” and “one carbon pool by folate” pathways were enriched in Saba piglets, while “limonene and pinene degradation”, “tryptophan metabolism”, and “sulfur relay system” pathways were enriched in Landrace piglets. In summary, the growth performance was higher for Landrace piglets compared with Saba piglets due to their genetic characteristics. The rich diversity and fewer infection-associated taxa were observed in Saba piglets, partially accounting for their higher adaptability to environmental perturbations than Landrace piglets. Furthermore, different pig breeds may regulate their health through different metabolic pathways.

Keywords

  • Saba piglets
  • Landrace piglets
  • jejunal content
  • the 16S rRNA gene
  • diversity

short-communication

Open Access

In vitro Antagonistic Activity of Endophytic Fungi Isolated from Shirazi Thyme (Zataria multiflora Boiss.) against Monosporascus cannonballus

Published Online: 05 Aug 2020
Page range: 379 - 383

Abstract

Abstract

Endophytic fungi viz., Nigrospora sphaerica (E1 and E6), Subramaniula cristata (E7), and Polycephalomyces sinensis (E8 and E10) were isolated from the medicinal plant, Shirazi thyme (Zataria multiflora). In in vitro tests, these endophytes inhibited the mycelial growth of Monosporascus cannonballus, a plant pathogenic fungus. Morphological abnormalities in the hyphae of M. cannonballus at the edge of the inhibition zone in dual cultures with N. sphaerica were observed. The culture filtrates of these endophytes caused leakage of electrolytes from the mycelium of M. cannonballus. To our knowledge, this is the first report on the isolation and characterization of fungal endophytes from Z. multiflora as well as their antifungal effect on M. cannonballus.

Keywords

  • antifungal
  • endophytic fungi

non-scientific

Open Access

Memorial Tribute

Published Online: 08 Sep 2020
Page range: 249 - 249

Abstract

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