Abdulina D. Sulfidogenic microbial communities of the technogenically transformed and natural ecotopes

The candidate degree thesis by speciality 03.00.07 - microbiology. Zabolotny Institute of Microbiology and Virology of the National Academy of Sciences of Ukraine, Kyiv, 2013. The thesis are dedicated to the study of phylogenetic and functional diversity of the sulfidogenic microbial community isolated from technogenically transformed and natural ecotopes, as well as the study of the possibility of interspecies interactions between the members of bacterial communities via plasmid transfer. Technogenesis was shown to influence the structure of the studied communities: the abundance of corrosive bacteria increased for the order of 2-4. The use of the cluster analysis with the principal component method showed the main factors which determined more than 50% of the investigated system variations.The taxonomic structure of the communities formed in the technogeniсally transformed soils and in the biofilm on the steel surface was characterized by phenotypic and molecular genetic identification. Natural sulfidogenic microbial community isolated from technogeniсally transformed soil included the bacteria of Desulfovibrio, Desulfotomaculum, Pseudomonas, Aeromonas, Enterococcus, Micrococcus, Bacillus genera. Biofilm sulfidogenic community consisted of the representatives of Desulfovibrio, Pseudomonas, Aeromonas, Stenotrophomonas and Bacillus genera. The sulfidogenic associations and the monoculture of Desulfovibrio sp. 10 were shown to synthesize protein during the biofilm growth, which exceeded the production level observed during the planktonic growth. Comparing to the plankton, the diversity of the bacterial cell morphological shapes in the biofilm decreased, the loss of flagella was observed and the extracellular formations were shown to appear. The possibility of the transfer and retention of the transmission plasmids RP4 and R68.45 to the bacteria - members of sulfidogenic microbial community was proved. As a result of the plasmid transfer the changes in the bacterial colony morphotype were observed. Transconjugated bacterial strains exhibited 1.5-2 times decreased resistance to the iron and copper ions. The presence of the plasmid-harboring strain P. aeruginosa 27(R68.45) among the members of the sulfidogenic microbial community led to the 2.5 times decrease in the protein synthesis during the biofilm formation and 2 times decrease in the corrosion rate.