Bacterial strains living in the environment must cope with the toxic compounds originating from humans production. Surface bacterial structures, cell wall and cytoplasmic membrane, surround each bacterial cell and create selective barriers between the cell interior and the outside world. They are a first site of contact between the cell and toxic compounds. Organic pollutants are able to penetrate into cytoplasmic membrane and affect membrane physiological functions. Bacteria had to evolve adaptation mechanisms to counteract the damage originated from toxic contaminants and to prevent their accumulation in cell. This review deals with various adaptation mechanisms of bacterial cell concerning primarily the changes in cytoplasmic membrane and cell wall. Cell adaptation maintains the membrane fluidity status and ratio between bilayer/nonbilayer phospholipids as well as the efflux of toxic compounds, protein repair mechanisms, and degradation of contaminants. Low energy consumption of cell adaptation is required to provide other physiological functions. Bacteria able to survive in toxic environment could help us to clean contaminated areas when they are used in bioremediation technologies.

The chapter describes the aspects of bioremediation that are related to survival and metabolism of bacterial degraders in the adverse environment contaminated with dangerous hydrophobic chemicals, polychlorinated biphenyls (PCBs). Successful environment decontamination requires bacterial strains that possess appropriate enzymes and are able to degrade particular contaminants. This chapter deals mainly with the adaptation mechanisms that allow bacteria to decrease toxic effects of the dangerous compounds on cytoplasmic membrane as the first contact point of pollutants and the bacterial cell. Many responses have been observed in bacteria that counteract the effects of toxic environmental organic pollutants: saturation-rigidification of cell membrane, cis/trans isomerization of fatty acids, increased content of cyclopropane fatty acids, and changes in branched fatty acids and cardiolipin, production of stress proteins, and elimination of toxic compounds using efflux pump. The study of these mechanisms is the first step in selection of appropriate resistant bacterial strains for bioremediation applications. Next steps should include study of degradation potential and efficacy of the most resistant strains. Setting up suitable experimental systems to examine the cell responses to toxic environmental organic pollutants in the adverse environment and optimal conditions for metabolism of bacterial degraders are important issues in the current bioremediation research agenda.

It is known that nanoiron has a high reducing activity, due to which it can effectively dechlorinate organic pollutants and reduce toxic metals. Presently, nanoparticles are being synthesized by physical and chemical methods that use toxic substances and require high energy supply. The increasing global demand for sustainable and green technologies drives the development of biological methods that might overcome those limitations. In the case of nanoparticles, phytogenic synthesis using plants or plant tissues can be carried out. The key role is played by bioactive substances present in plants and their interaction with iron precursors (ferric/ferrous salt). The present article provides a current insight into the process of the "green" synthesis of nanoparticles, with the focus on the key parameters that should be taken into account during both the synthesis and environmental application.