Chemical stress contribution in bacterial biofilm formation

<p>Background: The use of different chemicals for agriculture, industry and mining has caused pollution of agrarian soils which provokes changes in rhizosphere microflora. We have studied 10 bacterial strains isolated from a winter wheat Cd-polluted field in Ukraine by their taxonomic position, biochemical properties and resistance to 3 classes of toxicants: heavy metals (Cu<sup>2+</sup>, Cd<sup>2+</sup>), non-metals (perchlorate-ion), organic xenobiotic (1-chloro-4-nitrobenzene, CNB).  </p> <p>Objectives: To study the effect of toxicants on the biofilm–formation ability of individual strains and a mixed community.</p> <p>Methods: Biofilm characteristics (total microcosm growth, biofilm strength and attachment to the microcosm walls) were studied by combined biofilm assay (n = 4) with four treatments including 100 mg/L Cu<sup>2+</sup>, 25 mg/L Cd<sup>2+</sup>, 300 mg/L ClO<sub>4</sub><sup>-</sup>, and 100 mg/L CNB, with correlations and Principal component analysis (PCA) used to investigate data.</p> <p>Results: We found that microbial community had a greater resistance to the toxicants compare to individual strains. The presence of heavy metals increased the strength of biofilms, and in most cases growth and biofilm strength were positively correlated. However, in the presence of Cd<sup>2+</sup> this correlation was lost. Perchlorate affected bacteria, increasing mucus production and biofilm strength though it also reduced attachment levels. Finally, we also found that CNB could be used as a source of Carbon and energy during biofilm–formation.</p>

Assessment of the Waters’ Organic Xenobiotic Contamination Danger on the Basis of Information Techniques

Effectiveness of information techniques application for assessment of the water bodies’ xenobiotic pollution has been demonstrated. With the help of international and national databases, as well as calculative methods of the biological activity forecasting the degree of danger of the found organic compounds has been found. The list comprises toxicity of petroleum water pollution; organic xenobiotics found in the Moscow drinking water supply sources; substances that pollute the Baltic Sea; and chlorine/organic compounds produced in the process of waste water disinfection. Effectiveness if the information techniques application including search of data on a compound in international and national databases, forecast of biological activity and quantitative indicators with specialized software for assessment of water quality has been proved. A toxicity forecast has been carried out for organic compounds found in the sources of Moscow drinking water supply. This forecast enables to range these compounds in terms of their adversity degree, as well as predict possible by-effects for human beings and some species of hydrocoles. It has been shown that information techniques of the biological activity forecast can be used for defining of novel qualitative and quantitative data on this activity forms and the toxic effects’ concentration thresholds.