Characterization of oral bacterial diversity of irradiated patients by high-throughput sequencing.

The objective of this study was to investigate the compositional profiles and microbial shifts of oral microbiota during head-and-neck radiotherapy. Bioinformatic analysis based on 16S rRNA gene pyrosequencing was performed to assess the diversity and variation of oral microbiota of irradiated patients. Eight patients with head and neck cancers were involved in this study. For each patient, supragingival plaque samples were collected at seven time points before and during radiotherapy. A total of 147,232 qualified sequences were obtained through pyrosequencing and bioinformatic analysis, representing 3,460 species level operational taxonomic units (OTUs) and 140 genus level taxa. Temporal variations were observed across different time points and supported by cluster analysis based on weighted UniFrac metrics. Moreover, the low evenness of oral microbial communities in relative abundance was revealed by Lorenz curves. This study contributed to a better understanding of the detailed characterization of oral bacterial diversity of irradiated patients.

[Protective and reactivating effect of the protein exometabolite on yeast cells inactivated by the ultraviolet irradiation].

It has been shown that Saccharomyces cerevisiae, Kluyveromyces lactis, and Candida utilis strains produce the protein exometabolites, which has a protective and reactivating effect on the ultraviolet irradiated yeast cells. The protective effect of the preliminary ultraviolet irradiated (activated) protein exometabolite of all strains increased 2-3 times, though its reactivating activity did not change. Yarrowia lipolytica yeast cells, isolated from the areas with the high daily irradiation, and Endomyces magnusii, the obligate fungi parasites, were characterized by the highest ultraviolet tolerance in comparison with the other strains. However, they did not produce the exometabolites with the antistress effect. Luteococcus casei reactivating factor demonstrated protective and reactivating cross-action in relation to the ultraviolet irradiated S. cerevisiae, K. lactis, and C. utilis cells and were inactive in relation to Y. lipolytica and E. magnusii. Using killer and nonkiller S. cerevisiae strain, it has been shown that the peptide exometabolite accumulation was not associated with toxin production.

[Protective effect of extracellular protein metabolite of Luteococcus japonicus subsp, casei on cells subjected to heating and UV irradiation].

Extracellular protein metabolite isolated from the culture liquid of Luteococcus japonicus subsp. casei had reactivating and protective effects on UV-irradiated and heated cells. The extracellular metabolite, produced by cells in the logarithmic growth phase, was present in culture liquid in minuscule amounts. Mass spectral analysis showed that, along with the major component with a molecular weight of 7.6 kDa, the preparation contained low quantities of three minor proteins. Apparently, the biological activity of the exometabolite is determined by the major polypeptide component.

[The extracellular protein of Luteococcus japonicus subsp casei reactivates cells inactivated by ultraviolet radiation or heating]. / Vnekletochnyi belok Luteococcus japonicus subsp. casei reaktiviruet kletki, inaktivirovannye ul'trafioletovym oblucheniem i nagrevaniem.

The culture liquid of Luteococcus japonicus subsp. casei was found to be able to reactivate cells of this bacterium inactivated by UV irradiation or heat shock. The antistress activity of the culture liquid was due to the presence of an extracellular exometabolite of a protein nature with a molecular mass of more than 10 kDa. When the bacterium was grown in nutrient broth or glucose-containing mineral medium, the antistress protein was secreted by cells in the logarithmic growth phase. The reactivating effect of the antistress protein was inversely proportional to the survival rate of stressed cells.

[Extracellular protein metabolite of Luteococcus japonicus subsp. casei reactivates cells subjected to oxidative stress]. / Reaktiviruiushchee deistvie vnekletochnogo belkovogo metabolita Luteococcus japonicus subsp. casei na kletki, podvergnutye okislitel'nomu stressu.

A protein exometabolite isolated from the culture liquid of Luteococcus japonicus subsp. casei reactivates the cells of this microorganism, following H2O2 or paraquat-induced oxidative stress. The resistance of L. casei cells to these oxidizers is accounted for by the high activity of superoxide dismutase and catalase. The effect of the protein exometabolite is universal, in that it reactivates the cells after UV irradiation, heating, or oxidative stress. However, the cells subjected to oxidative stress are significantly less susceptible to the reactivating effect, as compared to their UV-irradiated or heated counterparts. Possible causes of these differences are discussed.

Effect of Propionibacterium acidipropionici on the growth of Yersinia enterocolitica.

The antibacterial effect of Propionibacterium acidipropionici culture on a whey medium was determined in preparations subjected to cell inactivation with UV radiation and chloroform treatment; in concentrated biomass, centrifuged and suspended in sterile water; in a preparation subjected to cell inactivation with chloroform. The test strain was Yersinia enterocolitica 8. The preparations and culture were added, as biopreservatives, to broth media where the test strain was cultured, checking periodically the population development. It was found that a whey culture of P. acidipropionici was characterized by antibacterial activity of 64 AU/ml, but after cell inactivation this activity decreased to 16 and 8 AU/ml, depending on the method employed. The activity of concentrated biomass of live cells was at a level of 128 AU/ml, and after inactivation with chloroform--8 AU/ml. An addition of biopreservatives to the growth medium caused inhibition of test strain proliferation. Its degree depended on the antibacterial activity of the environment and population size. In the environment with activity of 42.7 AU/ml the strain Y. enterocolitica 8 whose population was hundreds of cells per ml died after 8 hours of incubation. A larger population, i.e. 10(5) cfu/ml, survived under these conditions, but did not proliferate during 24 hours of culturing.