Enhanced Removal of Lindane by Actinomycetes Consortia

FUENTES, MARíA S.; SáEZ, JULIANA M.; BOURGUIGNON, NATALIA; CUOZZO, SERGIO A.; BENIMELI, CLAUDIA S.; AMOROSO, MARíA J.

San Diego

Encuentro; American Society for Micrbiology ASM one hundred tenth general meeting; 2010

Halogenated compounds are important environmental pollutants. Lindane is a halogenated insecticide prohibited in most countries but some are still using it for economic reasons and new sites are consequently being contaminated. Its bacterial degradation liberates chlorine by dehalogenase enzymes, playing an important role in this process. Lindane microbial degradation has been studied using pure and mixed microbial cultures. Mixed cultures have shown to be more suitable for bioremediation compared with pure cultures because their biodiversity can enhance environmental survival and increase the catabolic pathways available for contaminant biodegradation. The aim of this work was to evaluate the lindane removal capacity of isolated actinomycetes, individually and as a group under controlled laboratory conditions. Streptomyces sp. M7 (M7), Streptomyces coelicolor A3 (ScA3) and four actinomycetes isolates were cultivated alone in minimal medium (MM) with lindane for acclimation. These strains, as pure and mixed cultures, were cultivated in MM with lindane (1.66 mg L-1). Microbial cells were used to obtain cell-free extracts for dechlorinase activity assays and the supernatants from these cultures were used to determine residual lindane by gas chromatography. The isolates were characterized by 16S rDNA amplifications and sequenced. Enzyme activities ranged between 5.14 to 143.10 ìmolCl-/h/mg protein and percentage of lindane removal ranged between 11 to 62%.  The mixed culture A2-A5-M7-ScA3 showed the best activity but consortia A2-A5-ScA3, A8-A11-M7 and A2-A5-A11-M7 showed the minimal residual lindane value.  Because of no linear relationship between enzyme activity and residual lindane, was selected A2-A5-M7-ScA3 as the best consortium by analysis of the ratio between these two parameters. Actinomycetes were mostly identified as members of Streptomyces genus. These native streptomycetes present ability to grow as microbial consortium and to remove lindane. These actinomycetes consortia can be potentially used as a practically convenient technology for the biological removal of lindane.