Volume 4 (2020): Issue 3 (July 2020)

Downstream processing for recovery of microbial polyhydroxyalkanoate (PHA) biopolyesters from biomass constitutes an integral part of the entire PHA production chain; beside the feedstocks used for cultivation of PHA-production strains, this process is currently considered the major cost factor for PHA production.

Besides economic aspects, PHA recovery techniques need to be sustainable by avoiding excessive use of (often precarious!) solvents, other hazardous chemicals, non-recyclable compounds, and energy. Moreover, the applied PHA recovery method is decisive for the molecular mass and purity of the obtained product, and the achievable recovery yield. In addition to the applied method, also the PHA content in biomass is decisive for the feasibility of a selected technique. Further, not all investigated recovery techniques are applicable for all types of PHA (crystalline versus amorphous PHA) and all PHA-producing microorganisms (robust versus fragile cell structures).

The present review shines a light on benefits and shortcomings of established solvent-based, chemical, enzymatic, and mechanical methods for PHA recovery. Focus is dedicated on innovative, novel recovery strategies, encompassing the use of “green” solvents, application of classical “PHA anti-solvents” under pressurized conditions, ionic liquids, supercritical solvents, hypotonic cell disintegration for release of PHA granules, switchable anionic surfactants, and even digestion of non-PHA biomass by animals.

The different established and novel techniques are compared in terms of PHA recovery yield, product purity, impact on PHA molar mass, scalability to industrial plants, and demand for chemicals, energy, and time.

Cereal products are the most consumed in Romania being the main contributors to daily acrylamide exposure. The paper aims to present for the first time a general situation regarding the evolution of the acrylamide levels content from cereal products, on the Romanian market, during 2017-2018 periods, as a result of legislative measures imposed by the European Union (EU). For this purpose, the levels of acrylamide in 55 selected cereal products samples were evaluated. The cereal products analyzed were grouped in biscuits, confectionery, expanded cereals, bakery products and specialties. The acrylamide content from the cereal products were detected using GC-MS/MS method. The highest level of acrylamide was found in biscuits, whereas the lowest level was determined in bakery products. The most of the cereal products samples analyzed (90.9%) was below the reference levels established by the EU Regulation for the acrylamide level from 2017 EC (2013/647/EU) and 2018 EC (2017/2158/ EU). From the 55 cereal products analyzed, only 5 biscuits samples exceeded the reference levels established by the European Commission, one in 2017 and four in 2018 period.

Xylooligosaccharides (XOS) are the oligomers of β-1,4 linked xylose monomers and they have health promoting effect by modulating the beneficial microorganisms in intestine. In this study, hydrolysate obtained from hemp (Cannabis sativa) shives was investigated in terms of its in vitro toxicological impacts at cellular and genetic levels and antioxidant activity. The hydrolysate was found to contain 0.264 mg mL^-1 of xylose, 0.789 mg mL^-1 of xylobiose and 0.171 mg mL^-1 of xylotriose in addition to hydroxymethlyfurfural (HMF) and furfural (F) at concentrations of 0.545 mg mL^-1 and 0.107 mg mL^-1, respectively. The cells, colon epithelial cells (CoN) and colon cancer cells (Caco-2), exposed to 5.00 mg mL^-1 or lower XOS hydrolysate showed very similar growth profiles to the untreated control cells. At the genetic level, the oxidative responses of the cell types to XOS hydrolysate were different as measured by NFE2L2 (Nuclear factor, erythroid-derived 2-like 2) gene expression. Regarding antioxidant activity, the amount of XOS hydrolysate (IC₅₀) that cleared 50 % of the 2,2-diphenyl-l-picrylhydrazyl (DPPH) in the medium was calculated as 0.12 mg mL^-1. To conclude, based on in vitro studies, XOS hydrolysate obtained from lignocellulosic hemp shives emerges as an innovative, alternative and safe functional food candidate.

Lipid disorders have been implicated in overweight and menopause. However, evidence on lipidomic analysis of fatty acids in erythrocytes of menopausal women is scarce. The aim of this study was to investigate the relationship between the body mass index within or beyond 5 years of menopause and erythrocyte fatty acid profile. This case-control study was conducted on out of 37 menopausal women total patients, 22 with body mass index ≥ 25 and 12 matched controls (body mass index <25). Experimental procedures were performed on the blood through robotic equipment for isolation of erythrocyte and cell membrane fatty acids were analyzed by using gas-liquid chromatography. Results showed that erythrocyte membranes did not change significantly in lipid composition between case and control group. However, the percentage of women who had a physiological content of saturated fatty acids was lower in case than in control group, and the percentage of women who had a physiological content of monounsaturated fatty acids and polyunsaturated fatty acids was lower in control than in case group. Woman with BMI>25 and non-physiological content of fatty acids, were richer in percentage of saturated fatty acids and poorer of monounsaturated fatty acids and polyunsaturated fatty acids than women with BMI<25. The percentage of physiological n-6/n-3 polyunsaturated ratio was lower in women with BMI>25 than in women with BMI<25. Interestingly, the percentage of patients that had physiological values of lipids beyond 5 years of menopause increased in comparison patients within 5 years of menopause. Notably, n-6/n-3 polyunsaturated fatty acids physiological ratio beyond 5 years of menopause increased in both case and control patients, indicating normalization over time. In conclusion erythrocytes fatty acids composition may be related to the body mass index and to the time from menopause.

The goal of this study was to determine whether the Tethapod system, which was designed to determine the impedance properties of lipid bilayers, could be used for cell culture in order to utilise micro-impedance spectroscopy to examine further biological applications. To that purpose we have used normal epithelial cells from kidney (RPTEC) and a kidney cancer cell model (786-O). We demonstrate that the Tethapod system is compatible with the culture of 10,000 cells seeded to grow on a small area gold measurement electrode for several days without affecting the cell viability. Furthermore, the range of frequencies for EIS measurements were tuned to examine easily the characteristics of the cell monolayer. We demonstrate significant differences in the paracellular resistance pathway between normal and cancer kidney epithelial cells. Thus, we conclude that this device has advantages for the study of cultured cells that include (i) the configuration of measurement and reference electrodes across a microfluidic channel, and (ii) the small surface area of 6 parallel measurement electrodes (2.1 mm²) integrated in a microfluidic system. These characteristics might improve micro-impedance spectroscopy measurement techniques to provide a simple tool for further studies in the field of the patho-physiology of biological barriers.

Sepsis is a systemic infectious disease that leads to shock, organ failure, and death and requires urgent treatment. Animal model studies of sepsis and endotoxemia have revealed that antioxidant compounds prevent the progression of multi-system organ failure and reduce death rate. In the present study aimed to establish the effect of propolis, which has been proven to have antibacterial, anti-inflammatory and antioxidant activities in recent years, on lipopolysaccharide (LPS)-induced renal damage. 40 Sprague dawley rats were randomly divided into five equal groups (n = 8): Control (0.9% NaCl), LPS (30 mg/kg), propolis (250 mg/kg), propolis + LPS, and LPS + propolis. After completion of the experimental protocol, Malondialdehyde (MDA) levels were measured using blood serum samples obtained from the rats. The kidney samples of the rats were examined histopathologically. As a result, it was determined that LPS increased MDA levels in the blood serum samples and it caused histological changes in the kidney tissue such as tubular damage, mild ischemic injury, ischemic damage in the form of vacuolization, tubular epithelial vacuolization, vascular congestion, and glomerular atrophy. Contrary to these results, MDA levels of serum decreased in the propolis + LPS, and LPS + propolis groups, and also histological findings improved. These results showed that protective effect of propolis against kidney damage caused by LPS.

Endophytic fungi of selected Nigerian plants are important sources of bioactive products with enormous potentials for the discovery of new drug molecules for drug development. Pseudomonas aeruginosa is one of the major causes of healthcare-associated bacterial infections, leading to increased mortality and morbidity. In this study, isolated endophytic fungi from Cola nitida were screened for anti-pseudomonas properties. Endophytic fungi associated with healthy leaves of C. nitida were isolated using standard methods. Fungi were identified through their morphological, cultural and microscopic characteristics. The fungi were subjected to solid-state fermentation and secondary metabolites extracted using ethyl acetate and concentrated under vacuum. The crude extracts were screened for antimicrobial activity against clinical and laboratory strains of Pseudomonas aeruginosa using the agar diffusion method. The bioactive components of the fungal extracts were identified using High-Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) analysis. Three endophytic fungi; Acremonium sp., Aspergillus sp. and Trichophyton sp. were isolated. At 1 mg/ml, extracts of the three fungi displayed antipseudomonal activity with inhibition zone diameter ranging from 6 - 4 mm. HPLC-DAD analysis revealed the presence of compounds, such as 4-hydroxyphenyl acetate. indole-3-acetic acid, and protocatechuic acid among others in the fungal extracts. The findings in this study reveal that endophytic fungi associated with C. nitida possess promising antipseudomonal properties. This finding can open new doors for the discovery of new agents against P. aeruginosa.