Screening of yeasts for the production of 2-phenylethanol (rose aroma) in organic waste-based media.

In this study, we isolated 28 yeast strains from samples of plant material and fermented food and evaluated the possibility of efficient production of 2-phenylethanol (2-PE) in the organic waste-based media supplemented with l-phenylalanine (l-Phe). We used whey, a by-product from milk processing, as a base for media, and either glucose or three by-products from sugar beet processing as a fermentable carbon source. Ten newly isolated yeast strains were capable of producing over 2 g l-1 2-PE through the l-Phe biotransformation in a batch mode in standard medium. Among them, we selected eight strains producing 2-PE in a range of 1·17-3·28 g l-1 in 72 h batch cultures in shaking flasks in whey-based media. The strains were assigned to five species of Meyerozyma caribbica, Metschnikowia chrysoperlae, Meyerozyma guilliermondii, Pichia fermentans and Saccharomyces cerevisiae. While S. cerevisiae is known to be a promising producer of 2-PE, the four latter species are poorly studied on this application. Results presented here are better than other reported values for batch cultures of unmodified yeast strains. Therefore, it seems that whey and by-products from sugar beet processing might be a good feedstock for 2-PE bioproduction. SIGNIFICANCE AND IMPACT OF THE STUDY: 2-Phenylethanol (2-PE) is an alcohol with a pleasant rosy scent, which is commonly used in the food, fragrance and cosmetic industries as an aroma compound and preservative. Promising sources of 2-PE are yeasts, but still the biotechnological route has not been economically competitive to chemical synthesis. Thus, the first challenging goal to develop biotechnological production of 2-PE is the identification of highly productive yeasts and cheap feedstock. This study demonstrates for the first time the promising production of 2-PE by selected yeasts in organic waste-based media. This could pave the way for development of a cheaper method of 2-PE bioproduction.

Detection of human antibodies binding with smooth and rough LPSs from Proteus mirabilis O3 strains S1959, R110, R45.

Bacteria of the genus Proteus of the family Enterobacteriaceae are facultative human pathogens responsible mainly for urinary tract and wound infections, bacteremia and the development of rheumatoid arthritis (RA). We have analyzed and compared by ELISA the titer of antibodies in plasmas of healthy individuals and in sera of rheumatoid arthritis patients recognizing a potential host cross-reactive epitope (lysine-galacturonic acid epitopes) present in Proteus lipopolysaccharide (LPS). In our experiments LPSs isolated from two mutants of smooth Proteus mirabilis 1959 (O3), i.e. strains R110 and R45, were used. R110 (Ra type mutant) is lacking the O-specific polysaccharide, but possesses a complete core oligosaccharide, while R45 (Re type) has a reduced core oligosaccharide and contains two 3-deoxy-D-manno-oct-2-ulosonic acid residues and one of 4-amino-4-deoxy-L-arabinopyranose residues. Titer of P. mirabilis S1959 LPS-specific-antibodies increased with the age of blood donors. RA and blood donors' sera contained antibodies against S and Ra and Re type of P. mirabilis O3 LPSs. Antibodies recognizing lysine-galacturonic acid epitopes of O3 LPS were detected by ELISA in some plasmas of healthy individuals and sera of rheumatoid arthritis patients. RA patients antibodies reacting with P. mirabilis S1959 S and R LPSs may indicate a potential role of anti-LPS antibodies in molecular mimicry in RA diseases.

Irradiation with 365 nm and 405 nm wavelength shows differences in DNA damage of swine pancreatic islets.

INTRODUCTION: 3D printing is being used more extensively in modern biomedicine. One of the problems is selecting a proper crosslinking method of bioprinted material. Amongst currently used techniques we can distinguish: physical crosslinking (e.g. Ca2+ and Sr2+) and chemical crosslinking-the UV light crosslinking causing the biggest discussion. UV radiation is selectively absorbed by DNA, mainly in the UV-B region but also (to some extent) in UV-A and UV-C regions. DNA excitement results in typical photoproducts. The amount of strand breaks may vary depending on the period of exposition, it can also differ when cells undergo incubation after radiation. AIM: The aim of this study was to show whether and how the time of irradiation with 405 nm and 365 nm wavelengths affect DNA damage in cell lines and micro-organs (pancreatic islets). MATERIALS AND METHODS: The degree of DNA damage caused by different wavelengths of radiation (405 nm and 365 nm) was evaluated by a comet assay. The test was performed on fibroblasts, alpha cells, beta cells and porcine pancreatic islets after 24 hours incubation period. Samples without radiation treatment were selected as a control group. Results analysis consisted of determining the percent of cells with damaged DNA and the tail intensity evaluation. RESULTS: The degree of DNA damage in pancreatic islets after exposure to 405 nm wavelength oscillated between 2% and 6% depending on the tested time period (10 - 300 seconds). However, treating islets using 365 nm wavelength resulted in damage up to 50%. This clearly shows significantly less damage when using 405 nm wavelength. Similar results were obtained for the tested cell lines. CONCLUSIONS: Crosslinking with 405 nm is better for pancreatic islets than crosslinking with 365 nm UV light.