Membrane fatty acids adaptive profile in the simultaneous presence of arsenic and toluene in Bacillus sp. ORAs2 and Pseudomonas sp. ORAs5 strains

Abstract

Bacillus sp. ORAs2 and Pseudomonas sp. ORAs5, two arsenic-resistant bacterial strains previously isolated from sediments of the Orbetello Lagoon, Italy, were tested for their adaptation to mixed contaminants on the level of membrane fatty acid composition. The two bacterial strains were characterized by high levels of arsenic resistance, and Pseudomonas sp. ORAs5 was also shown to be solvent-tolerant. The bacterial strains were exposed to mixtures of two toxic compounds: arsenic at fixed concentrations and toluene in variable amounts or, alternatively, toluene at constant values along with arsenic added at variable concentrations. Both strains react to the contaminants by changing the composition of their membrane fatty acids. Bacillus sp. strain ORAs2 showed a correlation between growth rate decreases and fatty acids degree of saturation increases in both cases, although pointedly in the presence of 1, 2, and 3 mM of toluene and different additions of arsenic, counteracting membranes fluidity induced by toxic compounds. In Pseudomonas sp. ORAs5, adaptive changes in membrane composition was observed both in terms of increases in the degree of saturation and in the trans/cis ratio of unsaturated fatty acids in the presence of varying toluene and constant arsenic concentrations, whereas only minor changes occurred with increasing arsenic and constant toluene concentrations. Thus, on the level of membrane composition, Bacillus sp. ORAs2 showed a higher potential for adaptation to the presence of mixed pollutants, suggesting its probable suitability for bioremediation purposes.

Two naphthalene degrading bacteria belonging to the genera Paenibacillus and Pseudomonas isolated from a highly polluted lagoon perform different sensitivities to the organic and heavy metal contaminants

“…A similar behavior was previously pointed out for two arsenic-resistant bacterial strains, belonging to the genera Bacillus and Pseudomonas, isolated from sediments of the Orbetello Lagoon, where the Gram-positive bacterium showed higher tolerance to the presence of As 3? (Pepi et al 2008).…”

“…The bacteria continued to grow exponentially but at reduced growth rates. By plotting the relative growth rates against the concentrations of the toxic elements, a direct correlation between the concentration of a compound and its growth-inhibiting effect was observed as previously described (Pepi et al 2008). From these plots, the effective concentrations (EC50) of the metals leading to 50% growth inhibition were calculated and listed in Table 2.…”

“…In addition, the presence of toxic elements such as heavy metals and metalloids also affect degraders of organic pollutants (Pepi et al 2008).…”

The adaptation responses of bacterial cytoplasmic membrane fluidity in the presence of environmental stress factors — polychlorinated biphenyls and 3-chlorobenzoic acid

“…Some bacteria developed efficient adaptation mechanisms to survive in the hostile environment (Pepi et al 2008). Such resistant bacteria may play a major role in bioremediation technologies.…”

Metabolic varsality of bacteria isolated from surgace river sediment influenced by petrochemical effluentes: The case of Pseudomonassp. TN301 as polyhydroxyalkanoate producer

“…S obzirom na to da je kombinovano zagađenje životne sredine aromatičnim ugljovodonicima i metalima veoma često (Deeb i Altalhi, 2009;Pepi et al, 2009), kao i da je opisan inhibitorni efekat teških metala na aktivnost bakterijskih enzima uključenih u katabolizam aromatičnih jedinjenja (Pepi et al, 2008) Da bi se ispitao potencijalni efekat teških metala na rast sojeva u prisustvu aromatičnih jedinjenja kao jedinih izvora ugljenika i energije testirana je sposobnost korišćenja toluena, odnosno naftalena kao supstrata a u prisustvu metala. Pokazano je da su sojevi koji su ispoljili toleranciju na visoke koncentracije teških metala u prisustvu laktata kao izvora ugljenika zadržali tu sposobnost kada je laktat zamenjen toluenom, odnosno naftalenom.…”