Effect of Bacillus subtilis on the rumen microbial community and its components exhibiting high correlation coefficients with the host nutrition, growth, and development

T-RFLP investigation of the microbial community of the ruminal fluid of calves revealed changes in the microbiocenosis resulting from feeding the animals with biofilm-protected Bacillus subtilis cells. In the control animals, which switched from the diary to the vegetable diet, the phylum Firmicutes predominated Firmicutes (55.11 ± 1.97%), in particular the class Clostridia (53.10 ± 2.06%), families Lachnospiraceae (25.93 ± 1.41%) and Clostridiaceae (9.90 ± 1.35%). Members of the phyla Bacteroidetes (11.15 ± 2.88%) and Actinobacteria (9.27 ± 1.95%) were also present. Uncultured forms constituted 17.28 ± 2.01%. The share of bacilli (family Bacillaceae) was below 2% (1.46 ± 0.41%). Introduction of B. subtilis cells into the rumen of experimental animals increased the share of Bacillaceae to 2.80 ± 0.30%. The numbers of Thermoanaerobacteriaceae, Peptostreptococcaceae, and Alicyclobacillaceae increased by an order of magnitude. The numbers of Pseudomonadaceae, Burkholderiaceae, and uncultured Bacteroidetes increased twofold. Increased numbers of the rumen bacteria and protozoa, elevated fatty acid content, and higher ammonia emission indicated increased efficiency of digestion. Some families, including the domineering ones, included the members with different directions of the correlation with the indices of rumen digestion. The introduced bacilli stimulated the phylotypes with the positive correlation coefficients and suppressed those with the negative correlation. This, the rumen ecosystem was modified in the direction of improved digestion. The functional role of the members of the microbial community, for which the correlations were negative, weakly associated, or unassociated with the indices of rumen digestion are discussed.     

An unusual sexual stage in the alkalophilic ascomycete Sodiomyces alkalinus

Exploring life cycles of fungi is insightful for understanding their basic biology and can highlight their ecology. Here, we dissected the sexual and asexual life cycles of the obligate alkalophilic ascomycete Sodiomyces alkalinus that thrives at extremely high pH of soda lakes. S. alkalinus develops acremonium-type asexual sporulation, commonly found in ascomycetous fungi. However, the sexual stage was unusual, featuring very early lysis of asci which release young ascospores inside a fruit body long before its maturation. In a young fruit body, a slimy matrix which originates from the combined epiplasm of asci and united cytoplasm of the pseudoparenchymal cells, surrounds pooled maturing ascospores. Upon maturity, the ascospores are forcibly released through a crack in the fruit body, presumably due to an increased turgor pressure. These features of the sexual stage development resemble the ones found in unrelated marine fungi, indicating convergent evolution of the trait. We hypothesise these developmental features of S. alkalinus to be adaptive in the conditions of periodically inundated rims of soda lakes where the fungus thrives.     

Properties of the phenotypic variants of Pseudomonas aurantiaca and P. fluorescens

Different capacity for phenotypic variation of Pseudomonas aurantiaca and P. fluorescens in populations of cyst-like resting cells (CRC) during their germination on solid media, was shown to be a characteristic trait of biodiversity for the dormant forms of these bacteria. This biodiversity manifests itself as qualitative and quantitative differences in the spectra and emergence frequency of phenotype variants, obtained by plating of CRC, and depends on the conditions of CRC formation and storage time. In P. aurantiaca, the variation was associated with transition of the wild-type S-colonial phenotype into the R-type or the more pigmented P-type. These transitions were most pronounced for the CRC obtained under nitrogen depletion (a twofold N limitation), as well as under the influence of a chemical analogue of microbial anabiosis autoinducers, C₁₂-AHB. In the latter case, the frequency of S?R and S?P transitions (up to 70% and 80%, respectively) depended on the C₁₂-AHB concentration (1.0 × 10^?4 M and 2.5 × 10^?4 M) and on the storage time of CRC suspensions (from 3 days to 1.3 months). In the CRC populations grown in nitrogen-deficient media, R-type appeared with a frequency of up to 45% after at least four months of storage. In the case of P. fluorescens, S?R transitions depended not only on the storage time of CRC and C₁₂-AHB concentrations, but also on the composition of the solid medium used for plating. Differences were shown between the R-, P-, and S-variants of P. aurantiaca in such morphological, physiological, and biochemical characteristics as the growth rate (μ_max) in a poor medium, biomass yield (Y _max), resistance to streptomycin and tetracycline (LD₅₀), and the productivity in extracellular proteases. The R-and S-variants of P. fluorescens differed in their growth characteristics, resistance to high salinity and oxidative stress, as well as in their sensitivity to exogenous introduction of chemical analogues of microbial autoregulators (C₁₂-AHB and C₇-AHB). Hence, both the formation of dormant forms of the various morphological types [1] and intrapopulation phenotypic variability observed during their germination are important for the survival strategy of pseudomonads under unfavorable environmental conditions.     

Antibiotic resistance of Lactobacillus strains]

One hundred and thirty six Lactobacillus strains isolated from poultry and 23 Lactobacillus strains isolated from long-living persons were tested for their antibiotic sensitivity. Occurrence of some type determinants of resistance to aminoglycoside antibiotics and tetracyclines in the Lactobacillus strains resistant to these antibiotics was studied. The majority of the strains from the both collections were resistant to aminoglycosides (73 and 79 per cent, respectively). The isolates from the poultry were characterized by multiple resistance. The isolates from the long-living persons were most frequently resistant to one of two antibiotics. All the tested Lactobacillus strains isolated from the long-living persons were sensitive to tetracyclines. The species composition of the isolates was different. The antibiotic-resistant strains were detected in all the species involved in the study. By hybridization of Lactobacillus colonies with the probes containing various genes of the resistance it was shown that in 14 per cent of the antibiotic-resistant strains belonging to Lactobacillus the antibiotic resistance was controlled by the genes homologous to resistance genes widely distributed in gramnegative organisms. This indicated a possible wide exchange and heterologous expression of the antibiotic resistance determinants between microorganisms of various taxonomic groups.     

Nature of the distribution of synapses in the neurons of the reticular formation and some afferent nuclei]

Under study was the morphology of synaptic terminations of the brain reticular formation in cats and dogs as well as that of the afferent nuclei of the cat's posterior columns. The neurons of the Goll's and Burdach's nuclei have a richly ramified dendritic network. In this connection the main mass of synapses is disposed on the dendrites and their different branchings. The dendrites of the multipolar cells of the reticular formation have the main type of branching, but the cells are distributed from the nerve cell body at a considerable distance (up to 50 mu and more). The synapses are observed at the total length of the dendrite, so the axo-dendritic contacts quantitatively prevail over axo-somatic ones. The morphological data are compared with physiological axo-somatic and axo-dendritic concepts of the role of synapses in conducting the nerve impulse.     

Detection of the determinants of tetracycline A, B and C resistance in Shigella and Salmonella using DNA probes

Genetic determinants of tetracycline resistance of classes A, B and C were detected with DNA probes labeled with radioactive phosphorus (32P) in Shigella (44 strains) and Salmonella (50 strains). It was shown that in the Shigella strains the frequency of the Tet A gene amounted to 66 per cent, the frequency of the Tet B gene was equal to 84 per cent, the frequency of their combination was equal to 50 per cent and the frequency of the Tet C gene was nil. In the Salmonella strains the frequency of the Tet A, Tet B and Tet C genes was equal to 0.100 and 20 per cent, respectively, and that of their combination amounted to 20%. Possible use of the DNA probes in epidemiological analysis of outbreaks of Shigella and Salmonella infections is suggested.     

Monosaccharide composition of exopolymer complex in Thiobacillus thioparus and Stenotrophomonas maltophilia

The bacteria of Thiobacillus thioparus and Stenotrophomonas maltophilia are capable to form a thick biofilm complicated as to its structure on the surface of low-carbon steel. This biofilm formation on any surface occurs under the adhesion of the cells of the plankton growth model with the help of synthesis of muciferous exopolymers with adhesive properties. Hence the monosaccharide composition of the exopolymer complex in the form of polyol acetates was studied by chromate-mass-spectrum method. A significant difference in the composition of exopolymer monosaccharides with the presence of steel model in the medium and without it was established; a change in the monosaccharide composition of mono- and binary culture in the conditions of plankton and biofilm growth was also observed.     

Medicogenetic study of isolates in Uzbekistan. II. Anthropogenetic characteristics, blood groups and serum proteins]

A study is carried out on the distribution of ABO, MN, Rh, P and Le blood groups systems, haptoglobins, and common anthropogenetic features in the population of two villages of the Samarkand district. The examined samples have appeared to be heterogenous for ABO, Rh and P systems. For MN and Le unification is possible. The summary data on the allotment of phenotypes are as follows: (%) 0-30.2, A-35.3, B-26.2, AB-8.3, M-33.9, N-26.2, MN-39.9, Rh- -1.5, P-78.6, Le(a-b+)-33, Le (a+b-)-22.2, Le(a-b-)-34.2, Le(a+b+)-10.6. Gene frequencies have are calculated. The occurrence with regards to haptoglobins in both the villages is the same. The summary data are as follows: Hp1=1-4.8, Hp1=2-36.2, Hp2=2-59%. Gene frequencies have been calculated. In the population of the village Karakent there is a change of the frequency in many features of dermatoglyphics. The frequencies of anthropogenetic features do not differ between the villages. The summary data are the following: the frequency of theelbow type of hand is 86.9%, the right type of "hand clasping"-55.0%, the right type of "arm folding"-50.4%, righthandedness-99.7%. The occurence of square lobe of the ear is 21%, spliced one is 26.2%, the hanging down is 52.7%. The frequency of the gene insensitivity for PTC taste is 0.47 in one village and 0.53 in the other.