Escherichia coli possesses two hydrogenases, Hyd-3 and Hyd-4. These, in conjunction with formate dehydrogenase H (Fdh-H), constitute distinct membrane-associated formate hydrogenlyases, FHL-1 and FHL-2, both catalyzing the decomposition of formate to H(2) and CO(2) during fermentative growth. FHL-1 is the major pathway at acidic pH whereas FHL-2 is proposed for slightly alkaline pH. In this study, regulation of activity of these pathways by formate has been investigated. In cells grown under fermentative conditions on glucose in the presence of 30 mM formate at pH 7.5, intracellular pH was decreased to 7.1, the activity of Fdh-H raised 3.5-fold, and the production of H(2) became mostly Hyd-3 dependent. These results suggest that at alkaline pH formate increases an activity of Fdh-H and of Hyd-3 both but not of Hyd-4.
The mechanism formation of colonies and biofilms of bacteria and yeasts are studied always of great interest. The aim of the presented work was transmission and scanning electron microscopic analysis contacts between cells of bacteria and yeast in biomofilms on natural structures and inorganic surface, as a result of formation of close contacts between a cellular wall, a fringe, crosspieces, symplasts and cells of Escherichia coli, Shigella flexnerii Salmonella of typhi, Salmonella typhimurium and also some probiotic lactic acid on nutritious agar surfaces. Intercellular contacts in yeast biomofilms on plates of zirconium were scanning electron microscopic visualized by Candida guilliermondii.
As a result of electron microscopic studies of morphogenesis in yeast Candida guilliermondii NP‐4, the formation of new structures of volutin acidocalcisomes has been established within the cell cytoplasm. Under influence of X‐irradiation, the changes in morphometric and electron‐dense properties of yeast cells were identified: in yeast cytoplasm, the electron‐dense volutin granules were increased up to 400 nm in size. After 24‐h post‐irradiation incubation of yeasts, the large volutin pellets are fragmented into smaller number particles in size up to 25–150 nm. The ATPase activity in yeast mitochondria was changed under X‐irradiation. In latent phase of growth, ATPase activity was decreased 1·35‐fold in comparison with non‐irradiated yeasts. In logarithmic phase of growth, ATPase activity was three times higher than in latent phase, and in stationary phase of growth it has a value similar to the latent phase. Probably, the cells receive the necessary energy from alternative energy sources, such as volutin. Electron microscopy of volutin granule changes might serve as convenient method for evaluation of damages and repair processes in cells under influence of different environmental stress‐factors.
Investigation of fluorescence, electrophoretic and melting parameters of DNA of yeasts Candida guilliermondii NP-4 after X-radiation and posradiation repair was carried out. It was shown that under influence of X-radiation the rate of saturation of DNA by ethidium bromide and the melting temperature of yeast DNA was increased, and the melting interval was decreased. After repair period the rate of saturation of DNA by ethidium bromide and the melting temperature of yeast DNA were the highest, and the melting interval was the lowest, and in the electrophoregramms or repaired DNA there were additional low molecular fractions which testify about possible changes in DNA primary and secondary structures under influence of X-radiation and postradiation repair.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.