[Thermophilic bacterium Geobacillus uralicus growth is a function of temperature and pH: a synthetic chemostat model-based kinetic analysis ]

The synthetic chemostat model (SCM), originally developed to describe nonstationary growth under widely varying concentrations of the limiting substrate, was modified to account for the effects of nontrophic factors such as temperature and pH. The bacterium Geobacillus uralicus, isolated from an ultradeep well, was grown at temperatures ranging from 40 to 75 degrees C and at pH varying from 5 to 9. The biomass kinetics was reasonably well described by the SCM, including the phase of growth deceleration observed in the first hours after a change in the cultivation temperature. In an early stage of batch growth in a neutral or alkalescent medium, bacterial cells showed reversible attachment to the glass surface of the fermentation vessel. The temperature dependence of the maximum specific growth rate (micron) was fitted using the equation micron = Aexp(lambda T)/[1 + expB[1-C/(T + 273)]], where A, lambda, B, and C are constants. The maximum specific growth rate of 2.7 h-1 (generation time, 15.4 min) was attained on a complex nutrient medium (peptone and yeast extract) at 66.5 degrees C and pH 7.5. On a synthetic mineral medium with glucose, the specific growth rate declined to 1.2 h-1 and the optimal temperature for growth decreased to 62.3 degrees C.

[Clinical significance of studies of microorganisms of the intestinal mucosa by culture biochemical methods and mass fragmentography]

This research is a continuation of the series of studies of the parietal microbiota of the bowel tissue samplings by the gas chromatography and mass spectrometry (GCMS) method [G.A. Ossipov et al.//Journal of the Society of Russian Gastroenterologists, 2001, 1:54-69]. The purpose was to study a number of new microorganisms in view of new data on the composition of their fatty acids (FA) and aldehydes; to confirm the presence of a number of bacteria, fungi and aerobic actinomycetes revealed earlier by FA markers in the composition of the bowel parietal microbiota by their isolation in a pure culture; to amend the estimation of the clinical value of changes in the composition of the human bowel parietal microflora in case of irritable bowel syndrome (IBS) and antibiotics-associated diarrhea (AAD). We examined 31 patients with IBS with predominating diarrhea, 18 patients with AAD and 3 volunteers (a control group). We studied the blood samples, tissue samplings of the mucous coat of the jejunum, ileum and colon and composition of healthy people's feces. The GCMS method was applied. Morphology of defined strains was controlled by methods of light and scanning electron microscopy. We found a substantial portion of eubacteria among the bowel microorganisms and specific changes of their species in case of IBS and AAD. Taking into account their physiological and biochemical activity, when regulating their concentration one can expect at least the same effect as when regulating the number of bifidobacteria and lactobacilli in treatment of intestinal pathologies and other diseases related to bowel dysbacteriosis. The analysis of the feces microbiota using the GCMS method by FA of parietal microorganisms provides reliable data on their number both in feces and in tissue samplings. We found a substantial portion of eubacteria among other bowel microorganisms (27% in the jejunum and 16% in the colon) and specific changes of their species in case of IBS and AAD. The concentration of streptomycetes, rhodococci and other members of the Actinomycetales order becomes dozens times more and/or reduces in pathological states. The tenfold concentration of markers of lactobacilli and bifidobacteria in some diseases stimulates the differentiated application of widespread probiotics based on these bacteria.

[Geobacillus uralicus, a new species of thermophilic bacteria]

The K2T strain of thermophilic spore-forming bacteria was isolated from a biofilm on the surface of a corroded pipeline in an extremely deep well (4680 m, 40-72 degrees C) in the Ural. The cells are rod-shaped, motile, gram-variable. They grow on a complex medium with tryptone and yeast extract and on a synthetic medium with glucose and mineral salts without additional growth factors. The cells use a wide range of organic substances as carbon and energy sources. They exhibit a respiratory metabolism but are also capable of anaerobic growth on a nitrate-containing medium and of fermentation. Growth occurs within the 40-75 degrees C temperature range (with an optimum of 65 degrees C) and at pH 5-9. The minimum generation time (15 min) was observed at pH 7.5. Ammonium salts and nitrates are used as nitrogen sources. The G + C content of the DNA is 54.5 mol%. From the morphological, physiological, and biochemical properties and the nucleotide sequence of the 16S rRNA gene, it was concluded that the isolate K2T represents a new species of the genus Geobacillus, Geobacillus uralicus.

[Mossbauer data on the effect of NAD.H on the state of iron in bacteria]

The state of Fe of bacterial cultures of different systematic positions (Bacillus megaterium, Bacillus polymyxa, Pseudomonas putida, Pseudomonas fluorescens, Alcaligenes faecalis, Arthrobacter siderocapsulatus) grown on the medium containing Fe(III) citrate (up to 100 mg/l) with additional or without NAD.H was studied. The samples were in damp air-dry, second moistened, dried at 383 K states. Spectra have been obtained at 290 K and 100-200 K. The studied microorganisms have two types of atoms of Fe(III) which dissociated into protoplasm or into cell slug at damp state. All studied microorganisms except Arthrobacter siderocapsulatus do not reduce iron at all variants of experiments. Arthrobacter siderocapsulatus reduces about 50% of cell iron only the presence of NAD.H creating two types of Fe(II) complexes firmly connected with cell.