<abstract xmlns="http://www.w3.org/1999/xhtml">

Electricigens decompose organic matter and convert stored chemical energy into electrical energy through extracellular electron transfer. They are significant biocatalysts for microbial fuel cells with practical applications in green energy generation, effluent treatment, and bioremediation. A facultative anaerobic electrogenic strain SQ-1 is isolated from sludge in a biotechnology factory. The strain SQ-1 is a close relative of <italic>Klebsiella variicola</italic>. Multilayered biofilms form on the surface of a carbon electrode after the isolated bacteria are inoculated into a microbial fuel cell device. This strain produces high current densities of 625 μA cm–2 by using acetate as the carbon source in a three-electrode configuration. The electricity generation performance is also analyzed in a dual-chamber microbial fuel cell. It reaches a maximum power density of 560 mW m–2 when the corresponding output voltage is 0.59 V. The facultative strain SQ-1 utilizes hydrous ferric oxide as an electron acceptor to perform extracellular electricigenic respiration in anaerobic conditions. Since facultative strains possess better properties than anaerobic strains, <italic>Klebsiella</italic> sp. SQ-1 may be a promising exoelectrogenic strain for applications in microbial electrochemistry.
<fig id="j_pjm-2024-013_fig_006" position="float" fig-type="figure">
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</fig>
</abstract>

Isolation and Electrochemical Analysis of a Facultative Anaerobic Electrogenic Strain <italic>Klebsiella</italic> sp. SQ-1

<abstract xmlns="http://www.w3.org/1999/xhtml">

Proteases derived from <italic>Streptomyces</italic> demonstrate numerous commendable properties, rendering it extensively applicable in biotechnology and various industrial sectors. This study focused on the purification and characterization of the thermostable protease obtained from <italic>Streptomyces</italic> sp. CNXK100. The purified protease exhibited an estimated molecular weight of 27 kDa, with optimal activity at 75°C and pH 8.0. Notably, the enzyme remained active even without any metal ions and fully active in the presence of Na+, K+, Mg2+, and Cu2+metal ions. The kinetic parameters were determined with a <italic>KM</italic> value of 3.13 mg/ml and a <italic>Vmax</italic> value of 3.28 × 106 U/mg. Furthermore, the protease has demonstrated notable stability when subjected to a treatment temperature of up to 65°C for 60 minutes, and across a broad pH range extending from 5.0 to 10.0. This protease also demonstrated resilience against a spectrum of harsh conditions, including exposure to organic solvents, surfactants, bleaching agents, and proteolytic enzymes. Additionally, the enzyme maintained its activity following treatment with commercial detergents, accomplishing complete thrombus lysis at a concentration of 2.50 mg/ml within 4 hours. Remarkably, the protease exhibited stability in terms of activity and protein concentration for 70 days at 4°C. These findings underscore the potential industrial applications of the thermostable protease from <italic>Streptomyces</italic> sp. CNXK100.
<fig id="j_pjm-2024-014_fig_010" position="float" fig-type="figure">
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</fig>
</abstract>

Purification and Characterization of a Small Thermostable Protease from <italic>Streptomyces</italic> sp. CNXK100

<abstract xmlns="http://www.w3.org/1999/xhtml">

Sub-high temperature Daqu, a traditional solid fermenting agent used in Chinese strong-aroma Baijiu production, is abundant in diverse microorganisms, including bacteria, yeasts, molds, and actinomycetes. Among these, yeasts are pivotal for ethanol production and flavor formation. However, counting yeasts in Daqu is challenging due to interference from molds and bacteria. Antibiotics are employed to inhibit bacterial growth, but there is no practical way to suppress molds without affecting the growth of yeasts. In this study, short-chain carboxylates (C1-C6) were added to the culture medium at various pH conditions to investigate their effects on the growth of molds and yeasts. The results demonstrated distinct inhibitory effects of the short-chain carboxylates, depending on both pH and concentration. Several tested short-chain carboxylates effectively suppressed mold growth on agar plates while leaving yeast growth unaffected. This suggests a simple and feasible method for enhancing the efficiency of yeast isolation and counting in Daqu. Such an approach is valuable for studying yeasts in diverse and complex habitats.
</abstract>

Short-Chain Carboxylates Facilitate the Counting of Yeasts in Sub-High Temperature Daqu

<abstract xmlns="http://www.w3.org/1999/xhtml">

This study aimed to investigate azole resistance mechanisms in <italic>Aspergillus flavus,</italic> which involve <italic>cyp</italic>51A and <italic>cyp</italic>51B genes. Real-time Reverse Transcriptase qPCR method was applied to determine the overexpression of <italic>cyp</italic>51A and <italic>cyp</italic>51B genes for 34 <italic>A. flavus</italic> isolates. PCR sequencing of these two genes was used to detect the presence of gene mutations. Susceptibility test found sensitivity to voriconazole (VOR) in all strains. 14.7% and 8.8% of isolates were resistant to itraconazole (IT) and posaconazole (POS), respectively, with a cross-resistance in 5.8%. For the double resistant isolates (IT/POS), the expression of <italic>cyp</italic>51A was up to 17-fold higher. PCR sequencing showed the presence of 2 mutations in <italic>cyp</italic>51A: a synonymous point mutation (P61P) in eight isolates, which did not affect the structure of CYP51A protein, and another non synonymous mutation (G206L) for only the TN-33 strain (cross IT/POS resistance) causing an amino acid change in the protein sequence. However, we noted in <italic>cyp</italic>51B the presence of the only non-synonymous mutation (L177G) causing a change in amino acids in the protein sequence for the TN-31 strain, which exhibits IT/POS cross-resistance. A short single intron of 67 bp was identified in the <italic>cyp</italic>51A gene, whereas three short introns of 54, 53, and 160 bp were identified in the <italic>cyp</italic>51B gene. According to the models provided by PatchDock software, the presence of non-synonymous mutations did not affect the interaction of CYP51A and CYP51B proteins with antifungals. In our study, the overexpression of the <italic>cyp</italic>51A and <italic>cyp</italic>51B genes is the primary mechanism responsible for resistance in <italic>A. flavus</italic> collection. Nevertheless, other resistance mechanisms can be involved.
</abstract>

Investigation of Azole Resistance Involving <italic>cyp</italic>51A and <italic>cyp</italic>51B Genes in Clinical <italic>Aspergillus flavus</italic> Isolates

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Polish Journal of Microbiology

 eISSN: 2544-4646Print ISSN: 1733-1331   The Polish Journal of Microbiology (PJM), founded in 1952 as Acta Microbiologica, is a broad-based international microbiological journal covering: general microbiology, bacterial physiology, molecular biology and genetics, virology, clinical microbiology, environmental microbiology, and biotechnology.   The Polish Journal of Microbiology publishes mainly original research articles, including short communications, minireviews, book reviews, and press releases. The PJM is now an information exchange platform for authors who publish research findings and reviews on the latest developments in the field of microbiology.   The Polish Society of Microbiologists issues the Polish Journal of Microbiology. The origin of microbiology in Poland goes back to the XIX century. Professor Odo Bujwid (1857-1942) – was the first Polish bacteriologist, who graduated from the University of Warsaw and gained experience in Berlin working with Robert Koch, and in Paris at the Ludwik Pasteur Institute.   Polish Society of Microbiologists (PSM), formerly the Polish Society of Microbiologists and Epidemiologists, was established in Warsaw on October 31, 1927, at the First Congress of Polish microbiologists. The same year, PSM became a co-founder of the International Union of Microbiological Societies (IUMS), formerly the International Association of Microbiological Societies (IAMS). In 1974 PSM also became a co-founder of the Federation of European Microbiological Societies (FEMS), and from 2005 PSM is a member of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID). Currently, PSM aims to promote the development of microbiological sciences and popularize microbiology achievements among the Society's members and the broad public. PSM organizes congresses, scientific meetings, courses and lectures, and competitions of scientific papers..   The back issues of the journal are available here.   Rejection rate: 83%   Open Access Policy   This journal provides immediate open access to its content under the Creative Commons CC BY-NC-ND 4.0 license on the principle that making research freely available to the public supports a greater global exchange of knowledge. Under the CC BY-NC-ND 4.0 license users are free to share the work (copy and redistribute the material in any medium or format), if the contribution is properly attributed and used for non-commercial purposes. The material published in the journal may not be altered or build upon.   Fees   Articles are subjected to fees. The publication fee for all types of articles is 1000 USD + 23% VAT (if applicable). Depending on the country of origin, a fee may be subject to local taxes. Polish Journal of Microbiology does not offer fee waivers. Only the fee for corresponding authors who currently are members of the Polish Society of Microbiologists is reduced to 800 USD + 23% VAT, or equivalent in Polish zloty (PLN).     All inquiries regarding fees can be directed to our editorial office at editorial.office@pjmonline.org   ABOUT SOCIETY   The origin of microbiology in Poland goes back to the XIX century. Professor Odo Feliks Kazimierz Bujwid (1857-1942) – was the first Polish bacteriologist, who graduated from the University of Warsaw and gained experience in Berlin working with Robert Koch, and in Paris at the Ludwik Pasteur Institute.   Polish Society of Microbiologists (PSM), formerly Polish Society of Microbiologists and Epidemiologists, was established in Warsaw on October 31, 1927 at the first Congress of Polish microbiologists. Professor Zygmunt Szymanowski was elected the first President of PSM. The same year, PSM became cofounder of International Union of Microbiological Societies (IUMS), formerly International Association of Microbiological Societies (IAMS). In 1974 PSM also became cofounder of Federation of European Microbiological Societies (FEMS) and from 2005 PSM is a member of European Society of Clinical Microbiology and Infectious Diseases (ESCMID).   Within 90 years of activity, 28 Congresses of PSM were organized and 16 professors were elected as Presidents of PSM. At present, about 900 ordinary members and 19 honorary members, associated in 14 PSM branches all over Poland, belong to the Society. Besides, five companies active in the microbiological area support PSM as supporting members.   Currently, the aim of PSM is the same since its very beginnings: to promote the development of microbiological sciences and to popularize the achievements of microbiology among the Society's members and the broad public. PSM organizes congresses, scientific meetings, courses and lectures as well as competitions of scientific papers. Two quarterly journals, the Polish Journal of Microbiology and the Advances in Microbiology are issued by PSM. The Society formulates opinions on the conditions and needs of Polish microbiology and applies in these cases to the state authorities; cooperates with related associations in the country and abroad.   Archiving   Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.   Plagiarism Policy   The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process. 

Polish Journal of Microbiology

AHEAD OF PRINT

Isolation and Electrochemical Analysis of a Facultative Anaerobic Electrogenic Strain Klebsiella sp. SQ-1

Purification and Characterization of a Small Thermostable Protease from Streptomyces sp. CNXK100

Short-Chain Carboxylates Facilitate the Counting of Yeasts in Sub-High Temperature Daqu

Investigation of Azole Resistance Involving cyp51A and cyp51B Genes in Clinical Aspergillus flavus Isolates

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