Enrichment and Isolation of Endosulfan‐Degrading Microorganisms

Abstract

Endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,3,4-benzo-dioxathiepin-3-oxide) is a cyclodiene organochlorine currently used as an insecticide all over the world and its residues are posing a serious environmental threat. This study reports the isolation and identification of enriched microorganisms, capable of degrading endosulfan. Enrichment was achieved by using the insecticide as either the sole source of carbon or sulfur in parallel studies. Two strains each of fungi (F1 and F4) and bacteria (BF2 and B4) were selected using endosulfan as a sole carbon source. A Pandoraea species (Lin-3) previously isolated in our laboratory using lindane (gamma-HCH) as a carbon source was also screened for endosulfan degradation. F1 and F4 (Fusarium ventricosum) degraded alpha-endosulfan by as much as 82.2 and 91.1% and beta-endosulfan by 78.5 and 89.9%, respectively, within 15 d of incubation. Bacterial strains B4 and Lin-3 degraded alpha-endosulfan up to 79.6 and 81.8% and beta-endosulfan up to 83.9 and 86.8%, respectively, in 15 d. Among the bacterial strains isolated by providing endosulfan as a sulfur source, B4s and F4t degraded alpha-endosulfan by as much as 70.4 and 68.5% and beta-endosulfan by 70.4 and 70.8%, respectively, after 15 d. Degradation of the insecticide occurred concomitant with bacterial growth reaching an optical density (OD600) of 0.366 and 0.322 for B4 and Lin-3, respectively. High OD600 was also noted with the other bacterial strains utilizing endosulfan as a sulfur source. Fungal and bacterial strains significantly decreased the pH of the nutrient culture media while growing on endosulfan. The results of this study suggest that these novel strains are a valuable source of potent endosulfan-degrading enzymes for use in enzymatic bioremediation.

Atmospheric depositional fluxes and sources apportionment of organochlorine pesticides in the Pearl River Delta region, South China

“…In general, α-and β-endosulfan in technical endosulfan accounts for 70 and 30 %, respectively, and the ratio of α-/β-Endo in technical product is about 2.33 (Rice et al 1997). This ratio decreases since α-Endo decomposes faster (five to eight times) than β-Endo in the environment (Awasthi et al 1997;Siddique et al 2003;Gioia et al 2005). In this study, the average ratio of α-/β-endosulfan was 0.62 and 1.14 from dry deposition and bulk deposition samples, which was much lower than about 2.33, suggesting that endosulfan was aged and that there was little or no considerable fresh input of technical endosulfan in the PRD.…”

Biodegradation of 2,2,6,6-Tetramethyl-4-piperidone by three soil bacteria strains, their isolation and identification

“…The German Chemical Society (GDCh)-Advisory Committee (2004) procedure (Siddique et al, 2003), and 3 of them showed the best degrading ability. Enrichment was achieved by providing TMPD as sole carbon source.…”

“…Dilutions were spread onto MSM solid plates containing 150 mg/L TMPD and incubated at 30°C for 3 to 5 days. Colonies were picked from dilution plates based on distinct colony morphology and transferred onto fresh plates several times to ascertain culture purity (Siddique et al, 2003). Each strain was incubated in MSM medium containing TMPD (150 mg/L) and preliminary tested for its activity to TMPD degradation as the sole carbon source.…”

Biodegradation and Bioremediation of Organic Pesticides

“…F. ventricosum has been also proved to degrade endosulfan (63). It has been shown that fungal peroxidases and dioxygenases are involved in biodegradation of pentachlorophenol (64,65).…”