Biodegradation of γ-Hexachlorocyclohexane by Burkholderia sp. IPL04

The lindane (γ-Hexachlorocyclohexane, HCH) is recalcitrant man-made pesticide and due to its past agriculture use and had toxicity to human, other living organisms and its metabolites detected in the environment. The microorganisms can transform and/ degrade it by the mechanism of transformation and biodegradation, respectively. In this study, the degrading bacteria was isolated from the soil sample taken from contaminated site by the enrichment culture method. The finally selected isolate IPL04 was characterized for γ-HCH degradation by supplementation of mineral salt medium with γ-HCH (10-100 mg/L). It should degrade 98 of g-HCH in 8 days. The isolate IPL04 was characterized by biochemical characterization, microscopic examination and 16S rRNA based sequencing. This isolate was identified as Burkholederia sp. and its 16S rRNA sequence was submitted to NCBI GenBank with accession number MF120286. The antibiotic sensitivity tests were also conducted. Effect of pH, temperature and incubation time was standardized during the degradation. The intermediates produced during the degradation by Burkholederia sp strain IPL04 were identified by FTIR and GC-MS analysis. The intermediates of biodegradation pathway were detected as c-pentachlorocyclohexane (c-PCCH), Trichloro-2,5-cyclohexadiene-1-ol (TCCH-1-ol), 2,5-dichlorohydroquinone (DCHQ), 1,2-benzenedicarboxlic acid. The metabolic pathway for the degradation by IPL04 was also proposed. This study leads to the finding that Burkholederia sp. strain IPL04 has lindane degradation potential and may be employed in γ-HCH degradation of lindane contaminated sites.