Iumyna I. Biofilm of heterotrophic bacteria as a factor of protection coating Polyken 980-25 biodeterioration

3. Dissertation on the competition of scientific degree of the Candidate of Biological Sciences on speciality 03.00.07. - microbiology. - Zabolotny Institute of Microbiology and Virology of the NAS of Ukraine, Kyiv, 2010. The dissertation is dedicated to study of structural - functional peculiarities of biofilms, formed by mono- and binary cultures of Pseudomonas pseudoalcaligenes 109, Arthrobacter flavescens 102 and Bacillus subtilis 140 on the surface of Polyken 980-25 butil-rubber layer. The qualitative composition of natural association of heterotrophic bacteria that degradated completely the Polyken 980-25 butil-rubber layer has been studied. The causes of its degradation are presented by Pseudomonas pseudoalcaligenes 109, Arthrobacter flavescens 102 and Bacillus subtilis 140. The succession changes in this association have been studied. It was shown that during the first hour of biofilm formation Pseudomonas pseudoalcaligenes 109 is dominating and producing exopolymer matrix creating conditions for functioning of another associants. After two hours Arthrobacter flavescens 102 has been detected and after six hours - Bacillus subtilis 140 was detected too. With the help of CLSM the biofilm architectonic of mono- and binary cultures of Pseudomonas pseudoalcaligenes 109 and Arthrobacter flavescens 102 have been investigated. It was shown the clearly expressed heterogenity of the binary biofilm. This biofilm has the unequal profile and many voids. The layer of the opaque slame is the base of the biofilm. In the binary biofilm it is shown the distribution of bacteria: immediately on the surface of the butil-rubber layer the cells of Arthrobacter flavescens 102 have been revealed. The investigation of dynamics of biofilm making by mono- and binary cultures (changes of the biofilm thickness) showed the presence of definite stagies of biofilm formation. It has been established the specific productivity of the exopolymer complex (EPC) that at the biofilm growth was more than at the planctonic growth: for Pseudomonas pseudoalcaligenes 109 - twice, for Arthrobacter flavescens 102 - 10 times, for the association - 8 times. At the planktonic growth the quantity of carbohydrates and protein in EPC was considerably more than in the biofilm EPC. The monosaccharide composition of mono- and binary cultures EPS at different growth forms was studied. At the biofilm growth the monosaccharide composition is more diverse. Xylosa was detected in the biofilm EPS only. The physics - chemical parameters of the Polyken 980-25 coating have been studied. It is shown that the rupture to strength during six months is decreased: under the influence of Pseudomonas pseudoalcaligenes 109 - on 5,6 %, Arthrobacter flavescens 102 - on 9 % and the bacteria association - on 20 %. It is proposed the possible biodegradation mechanism of the butil - rubber layer that is connected with the rupture of double CH-groups linkage and increase of carbonyl groups (C=O) i.e. with oxidative destruction.