Effects of certain physical stresses on the composition of the membrane of bacteria implicated in food and environmental contamination.

Bacterial membranes are implicated in the adaptation process of bacteria to numerous environmental conditions. In this context, our aim was to explain the consequences of a few physical stressor factors, like UV radiations and magnetic fields underlying the structural adaptation of cellular membranes to physical factors. The goal was also to review the state of the art about the link between membrane composition and bacterial resistance. According to comparative studies between ionizing γ-radiation, non-ionizing UVc radiations and Static Magnetic Field SMF, the response of some Gram negative bacteria appears to be generalized and was manifested by a membrane unsaturation, because of a production peak of unsaturated fatty acids. However, disturbances found inside the membrane, after UVB and Pulsed Electric Field (PEF) exposure were marked by a lower unsaturated fatty acids rate. This result is not concordant to disturbance seen after UVC treatment, even if the treatment is by UV radiation.

Exhaustion of pentachlorophenol in soil microcosms with three Pseudomonas species as detoxification agents.

Pentachlorophenol (PCP) is a toxic compound, which is widely used as a wood preservative product and general biocide. It is persistent in the environment and has been classified as a persistent organic pollutant to be reclaimed in many countries. Bioremediation is an emerging approach to rehabilitating areas polluted by recalcitrant xenobiotics. In the present study, we evaluated the potential of three strains of Pseudomonas (P. putida S121, P. rhizophila S211, and P. fuscovagiceae S115) as bioremediation agents in depletion and detoxification of PCP in soil microcosms. PCP removal was effectively optimized using a central-composite experimental design and response surface methodology (RSM). The optimum conditions for maximum PCP removal yield (85 ± 5%) were: 500 mg/kg PCP concentration, 108 UFC/g soil inoculum size of each strain and 55 days incubation period. The bacterial strains, P. putida, P. rhizophila, and P. fuscovagiceae, showed good capability to tolerate and degrade PCP so that they could be successfully used in synergistic effect to treat PCP polluted soils.