Том 86, № 1 (2017)

The rapid growth of chemical industries has resulted in increased production of halogenated compounds in the form of solvents, herbicides, insecticides, fungicides, intermediates for chemical synthesis etc.; that have subsequently added up in the environment. However, dumping of these compounds in the environment have directly or indirectly resulted in many health hazards to the animals including human being. Therefore, now a day’s microbial based degradation of these halogenated compounds is considered as a cost effective and potential method of treatment. 3 Chloropropanoic acid (3-CPA) is a less studied beta-chlorinated aliphatic compound and is widely used in agricultural industry as a herbicide and is highly toxic in nature. There is hardly any report that describes the microbial based dehalogenation mechanism and degradation of this haloacid pollutant. This review narrates the biochemical process involved in the microbial dehalogenation process in general and degradation of 3-CPA in particular. Here we have also elucidated the metabolic potential of 3-CPA, its degradation pathways with proposed future research aspects.

Yeast abundance and species diversity on the surface and in inner tissues of Malus domestica and Pyrus communis fruits under high anthropogenic impact in the city of Moscow (Russia) were studied. Results demonstrated that abundance of epiphytic yeasts on the fruits increased gradually, reaching the maximum of 3.2 × 10⁴ CFU/g on mature fruits. During summer, abundance of endophytes did not change significantly (variation near 2.5 × 10³ CFU/g) until complete maturation, while in September their numbers increased to 10⁴ CFU/g. Basidiomycetous yeasts (Filobasidium wieringae, F. magnum, Rhodotorula glutinis, and Rhodosporidiobolus colostri) predominated on the fruit surface. Ascomycetous species were the most diverse group inside the fruits, which quantitatively increased through maturation. It was found that the share of opportunistic species Candida parapsilosis in internal tissues was significant during the entire period of fruit formation and development under anthropogenic impact in the city. Specific properties of epiphytic and endophytic yeast communities developing in natural ecological niches under synanthropic conditions and anthropogenic impact are discussed.

The effect of ultramicrobacterial epibionts of the genera Kaistia (strain NF1), Chryseobacterium (strain NF4), and Stenotrophomonas (strain FM3) on the process of sporulation of Bacillus subtilis ATCC 6633 was studied. The investigated strains of ultramicrobacteria (UMB) were found to inhibit the sporulation process of B. subtilis ATCC 6633 in binary mixed cultures, exhibiting a 3-day delay of the onset of sporulation compared to the control one, an extended period of the prospore maturation, formation of the fraction of immature spores, and development of ultrastructural defects in many endospores. Thus, investigation of binary mixed cultures of B. subtilis and UMB revealed that, apart from suppression of reproduction and lysis of host vegetative cells, inhibition of spore formation and destruction of endospores was yet another feature of intermicrobial parasitism. The UMB parasites of the studied genera are assumed to participate in the regulation of development and reproduction of B. subtilis in natural habitats of this spore-forming bacterium.

The lipopolysaccharide (LPS) of Escherichia coli 126 was isolated and studied. The lipid A fatty acid composition of the investigated LPS was similar to that of other members of the family Enterobacteriaceae. The E. coli 126 LPS was more toxic than the LPSs of previously studied E. coli strains and of other members of the Enterobacteriaceae (Budvicia aquatica and Pragia fontium), and was less pyrogenic than pyrogenal. SDS-PAG electrophoresis showed a bimodal distribution typical of S-form LPSs. The LPS of E. coli 126 decreased the adhesive index indicating a possible competition between LPS molecules of E. coli 126 and adhesins of E. coli F-50 on rabbit erythrocytes. The LPS of E. coli 126 in a homologous system showed antigenic activity in the reactions of double immunodiffusion in agar by Ouchterlony. No serological cross-reaction of the LPS of other E. coli strains, as well as of that of the B. aquatica type strain, with the antiserum to E. coli 126 was observed. The structural components of the lipopolysaccharide obtained by mild acid hydrolysis were lipid A, the core oligosaccharide, and the O-specific polysaccharide. Based on the data of monosaccharide analysis and ¹H and ¹³C NMR spectroscopy it was found that the O-specific polysaccharide had the structure characteristic of the representatives of E. coli serogroup O15.

The present study introduced and evaluated modification of E. coli BL21 (DE3) to improve its biosorption capacity by the transfer of the Corynebacterium glutamicum metallothionein gene (C.gMT). The C.gMT sequence was extracted and cloned in pET28a vector and the ligation product was transferred into E. coli BL21 (DE3). It has been also submitted to the GenBank database (accession number KJ638906.1). The performance of the recombinant bacterium was evaluated at different metal ions concentrations, contact times, pH values, and co-ions. The results show that recombinant BL21 (DE3) was able to uptake Pb⁺², and Zn⁺² at greater percentages than could BL21 (DE3). The optimum pH for the removal of each heavy metal was different. As contact time increased, Pb⁺² and Zn⁺² biosorption by the recombinant bacterium increased, while the biosorption of Cd⁺² remained at a nearly steady rate for contact times of more than 1 h. Increasing the concentrations of Pb⁺² and Zn⁺² in solution increased biosorption of these metals by the recombinant BL21 (DE3) over that of Cd⁺². It could be hypothesized that Pb⁺² and Zn⁺² removal by C.gMT-engineered BL21 (DE3) occurred mainly via intracellular biosorption (absorption) and that Cd⁺² was mainly taken up through cell surface biosorption (adsorption).

A facultative methylotrophic bacterium, strain Lp-1, which was isolated from root nodules of lupine (Lupinus polyphyllus L.) on the medium with methanol as a carbon and energy source, exhibited high similarity of the 16S rRNA gene sequences to Delftia strains (94‒99.9%). The cells of Delftia sp. Lp-1 were motile gram-negative rods dividing by binary fission. Predominant fatty acids were C_16:0 (34.2%), C_16:1ω9 (14.5%), and C_18:1ω7c (17.3%). Phosphatidylethanolamine, phosphatidylcholine, and phosphatidylglycerol were the dominant phospholipids. Q₈ was the major ubiquinone. Optimal growth occurred at 24‒26°C and pH 7.1‒7.3; growth was inhibited by 1% NaCl. The organism oxidized methanol with the classical methanol dehydrogenase and used the ribulose bisphosphate pathway of C₁ metabolism. Analysis of translated amino acid sequence of the large subunit of the MxaF methanol dehydrogenase revealed 85.5‒94% similarity to the sequences of such autotrophic methylotrophs of the class Alphaproteobacteria as Angulomicrobium, Starkeya, and Ancylobacter, indicating the possible acquisition of the mxaF gene via horizontal gene transfer. Delftia sp. Lp-1 (VKM B-3039, DSM 24446), the first methylotrophic member of the genus Delftia, was shown to be a plant symbiont, stimulating plant growth and morphogenesis, increasing the level of photosynthetic pigments and specific leaf weight. It possesses the nifH gene of nitrogen fixation, is capable of phosphate solubilization, synthesis of auxins and siderophores, and is antagonistic to plant pathogenic fungi and bacilli.

During the summer period (15–25°C), 34 strains of methylotrophic bacteria associated with different species of herbs, shrub, and trees in Pushchino (Moscow oblast, Russia) were isolated on the medium with methanol. Predominance of pink-colored Methylobacterium strains in the phyllosphere of many plants was confirmed by microscopy, enumeration of the colonies from grass leaves, and sequencing of the 16S rRNA genes. Colorless and yellow-pigmented methylotrophs belonged to the genera Methylophilus, Methylobacillus, Hansschlegelia, Methylopila, Xanthobacter, and Paracoccus. All isolates were able to synthesize plant hormones auxins from L-tryptophan (5−50 μg/mL) and are probably plant symbionts.

We investigated the bacterial community structure of Soldhar hot spring with extreme high temperature 95°C located in Uttarakhand, India using high throughput sequencing. Bacterial phyla Proteobacteria (88.8%), Deinococcus-Thermus (7.5%), Actinobacteria (2.3%), and Firmicutes (1.07%) were predominated in the sequencing survey, whereas Bacteroidetes, Verrucomicrobia, Aquificae and Acidobacteria were detected in relatively lower abundance in Soldhar hot spring. At the family level, Comamonadaceae (52.5%), Alteromonadaceae (15.9%), and Thermaceae (7.5%) were mostly dominated in the ecosystem followed by Chromatiaceae, Microbacteriaceae, and Cyclobacteriaceae. Besides, members of Rhodobacteraceae, Moraxellaceae, Xanthomonadaceae, Aquificaceae, Enterobacteriaceae, Bacillaceae, Methylophilaceae, etc. were detected as a relatively lower abundance. In the present study we discuss the overall microbial community structure and their relevance to the ecology of the Soldhar hot spring environment.