The purpose of this work was the isolation of the predominant representatives of sulfate-reducing bacteria (SRB) of the sulfidogenic microbial community separated from the soil ferrosphere and the examination of their morphological, physiological, biochemical and genotypic peculiarities, the evaluation of some physiological processes under co-culturing with their satellite species Anaerotignum propionicum. During the study two isolates of sulfate-reducing bacteria NUChC SRB1 and NUChC SRB2 were obtained from sulfidogenic microbial community isolated from soil ferrosphere on Postgate's "B" medium and their belonging to different strains (using ISSR-PCR method) was proved. As a result of molecular-genetic analysis of the strains, a 16S rRNA gene fragments of 613 bp and 522 bp were amplified and sequenced. The strains were identified as Desulfovibrio oryzae by the complex of microbiological, physiological and biochemical features and on the basis of 16S rRNA gene sequences (phylogenetic analysis). The 16S rRNA gene sequences were submitted in GenBank as MT102713 (NUChC SRB1) and MT102714 (NUChC SRB2). The co-cultivation of isolated SRB strains with A. propionicum NUChC Sat1 strain (in the absence of electron donors, the presence of sulfates and yeast extract) showed the formation of sulfur-reducing bacteria of hydrogen sulfide, which was not observed during their mono-cultivation. In this case, the phenomenon of syntrophy probably takes place-co-growth on the nutrient substrate, and the electron donor appears due to the use of the yeast extract compounds by the NUChC Sat1 strain. Therefore, in the sulfidogenic community isolated from the soil ferrosphere, there is a mutual growth of the association of bacteria D. oryzae and A. propionicum, which is caused by trophic interaction. Possibly the contribution of these associated bacteria to the corrosion process lies in the utilization of hydrogen (D. oryzae) and the formation of substrate products of SRB metabolism (hydrogen and organic acids), which are both corrosive compounds (A. propionicum). Without a doubt the corrosion process involving this association needs further investigation.ferrosphere, sulfate-reducing bacteria, Desulfovibrio oryzae, 16S rRNA gene, ISSR-PCR.

It was evaluated the antibiofilm-forming properties of NUChC C1 and NUChC C2b isolates (from the collection of the Department of Biology of the T.H. Shevchenko National University "Chernihiv Colehium") against the sulfate-reducing bacteria biofilms on the poly(ethylene terephthalate) surface. NUChC C1 and NUChC C2b isolates were isolated by classical microbiology methods on Postgate's "B" medium and their cultural-morphological, some physiological-biochemical properties and molecular-genetic characteristics were investigated. To identify bacteria the sequencing and analysis of the 16S rRNA gene were carried out. The bacteria were identified as Bacillus velezensis. Based on PCR-ISSR analysis, it was found that the studied bacteria belong to different strains. The 16S rRNA gene sequences were submitted in GenBank as MN508954.1 (NUChC C1), MN749356.1 and MN749357.1 (NUChC C2b). In the genome of B. velezensis the presence and transcriptional activity of the genes for the synthesis of bacillibactin (dhbC, dhbF), fengycin (fenA) and polyglutamic acid (epsK) were studied. Among these only genes belonging to bacillibactin synthesis operon were detected and only they demonstrated activity. The observed mode of dhbC and dhbF genes expression during 144 hours of cultivation differed between two B. velezensis strains: gradually increasing in NUChC C1 and sharply increased after 24 hours with decreasing on 144th hour in NUChC C2b. Antagonistic properties of the studied strains of B. velezensis against sulfate-reducing bacteria Desulfovibrio oryzae NUChC SRB1 and NUChC SRB2 were not observed. Siderophore-producing strains of Bacillus velezensis inhibit the formation of bacterial biofilms on the polymeric material poly(ethylene terephthalate) during its long-term exposure (50 days) in a culture of sulfate-reducing bacteria under conditions of sufficient iron supply. Bacillibactin-producing strains prevent the development of bacterial biofilms on the poly(ethylene terephthalate) surface. This is one of the reasons for the prolongation of the process of poly(ethylene terephthalate) biodegradation in natural ecosystems.

This paper tackles bacteria of the genus Bacillus as both biodamaging/biodegrading and biocontrolling agents. The article addresses the said bacteria’s ability to form biofilms and corrosive, antimicrobial and antibiofilm proactive compounds, primarily, siderophores. Their role depends on the species, microorganism strain, production of antimicrobial substances, biofilm formation, and the type of damaged material. The bacteria under analysis have demonstrated the ability to cause as well as inhibit biodamage. The involvement of bacteria of the genus Bacillus in microbiologically influenced corrosion processes is determined by the production of corrosive metabolites and the impact of certain bioelectrochemical mechanisms. Lipopeptides generated by Bacillus subtilis (surfactin, iturin and fengycin) are capable of modifying surfaces’ hydrophobic properties and impacting the microbes’ adhesion to surfaces. Produced by Bacillus velezensis, the siderophore bacillibactin at a high concentration is capable of inhibiting the formation of bacterial biofilms, thus slowing down the degradation of materials. Further study of siderophores as green inhibitors of microbiologically influenced corrosion may be promising as the said compounds possess antibiofilm-forming properties and high-intensity inhibitory capabilities.

Aim. To determine the response of the populations of Erysipelothrix rhusiopathiae and Leptospira interrogans pathogenic microorganisms to the impact of broadleaf cattail (Thypha latifolia) root diffusates. Methods. Aqueous solutions of T. latifolia root diffusates were sterilized by vacuum fi ltration through the fi lters with 0.2-micron pore diameter. The experimental samples contained cattail secretions, sterile water, and cultures of E. rhusiopathiae or L. interrogans. The same amount of sterile water, as in the experimental samples, was used for the purpose of control, and the same quantity of microbial cultures was added in it. After exposure, the density of cells in the experimental and control samples was determined. Results. Root diffusates of T. latifolia caused an increase in cell density in the populations of E. rhusiopathiae throughout the whole range of the studied dilutions (1:10–1:10000). In the populations of the 6 studied serological variants of L. interrogans spirochetes (pomona, grippotyphosa, copenhageni, kabura, tarassovi, canicola), the action of broadleaf cattail root diffusates caused the decrease in cell density. A stimulatory effect was marked in the experimental samples of the pollonica serological variant of leptospira. Conclusions. The populations of E. rhusiopathiae and L. interrogans pathogenic microorganisms respond to the allelopathic effect of Thypha latifolia by changing the cell density. The obtained results provide the background to assume that broadleaf cattail thickets create favorable conditions for the existence of E. rhusiopathiae pathogen bacteria. The reduced cell density of L. interrogans in the experimental samples compared to the control samples observed under the infl uence of T. latifolia root diffusates suggests that reservoirs with broadleaf cattail thickets are marked by the unfavorable conditions for the existence of pathogenic leptospira (except L. pollonica).

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