Biofilms of a number of gram-positive and gram-negative bacteria (both environmental strains from the stratal waters of oil fields and collection strains) were found to exhibit higher resistance to extreme physicochemical factors (unfavorable temperature, pH, and salt concentration) than planktonic cultures. The extracellular polymers forming the structure of the biofilm matrix were shown to contribute significantly to this resistance, since suppression of matrix formation by subbacteriostatic concentrations of azithromycin (for Pseudomonas acephalitica) or mutation in the cvil gene encoding N-hexanoyl homoserine lactone synthetase (for Chromobacterium violaceum CV026) resulted in the resistance of biofilms being decreased almost to the level of planktonic cultures. The role of the biofilm matrix for bacterial survival under extreme conditions is discussed.

Controlling the formation and reconstruction of microbial biofilms is of ever increasing importance for the ecological, medical, and biotechnological aspects of biofilm studies. The goal of this review was to provide systematization and analysis of the results obtained in recent years on the modes and mechanisms of the stimulatory or inhibitory effect of extreme factors and biocidal agents on biofilm formation. Special attention is paid to controlling the formation of medically (infective diseases, implant biofouling) and technologically or biotechnologically important biofilms (bioremediation, biocorrosion, and biosynthesis of biologically active compounds).

The mechanisms of microbial action on synthetic plastics are analyzed, with the focus on the most widespread polymers produced on an industrial scale. The effect of microbial enzymes on plastic biodegradation and the role of multispecies biofilms in biocorrosion are considered. The main approaches for protection of synthetic plastics from microbially caused damage are discussed.

The distribution, colonization, and biodegradation of primary and secondary microplastics, as well as were effect on the plastisphere ecological systems, are analyzed. The pathways of microplastic contamination of the atmosphere, hydrosphere, and lithosphere are described. The composition of multispecies communities colonizing the microplastics and their differences from environmental communities unassociated with plastic within the same habitat are considered. The processes of microplastic biodegradation and their role as vectors for transfer of genetic information affecting the structure of natural microbial communities and for the propagation of toxic components are discussed.

Search for inexpensive efficient compounds with antibiofilm activity, which could be applied both for treatment of biofilm-associated infections and in other cases requiring biofilm elimination, is presently of importance. For this purpose we chose niclosamide. Niclosamide is a widespread and available anthelmintic drug, which was also recently shown to suppress bacterial growth. High antibiofilm activity of niclosamide against a range of gram-positive bacteria isolated from different ecological niches was shown. According to our results, niclosamide may be a promising component of composite antibiofilm preparations.