Degradation of [8,9,-14C]endosulfan by soil microorganisms

Abstract

Twenty-eight soil fungi, 49 soil bacteria, and 10 actinomycetes were tested as to their ability to degrade the insecticide endosulfan. Using 14C-labeled material, the qualitative as well as the quantitative formation of metabolities, as well as of 14CO2, could be followed. Sixteen fungi, 15 bacteria, and 3 actinomycetes were found capable of metabolizing more than 30% of the applied endosulfan. The major metabolities detected were endosulfate, formed by oxidation of the sulfite group, and endodiol, formed by hydrolysis of the ester bond. The majority of highly active fungi formed endosulfate as the major metabolite, whereas the majority of active bacteria formed endodiol. In addition to endosulfate and endodiol, individual cultures contained small quantities of endohydroxyether and two unidentified products. The very small quantities of 14CO2 evolved from cultures indicated that an extensive mineralization of the carbon skeleton of endosulfan did not occur.

Klebsiella pneumoniae KE-1 degrades endosulfan without formation of the toxic metabolite, endosulfan sulfate

“…During endosulfan degradation by KE-1, the culture pH decreased to 6.9, but endosulfan sulfate was not detected during the 10 days of incubation. This is in agreement with a previous report [4] that some bacteria, such as Corynebacterium sp., Bacillus polymyxa, Pseudomonas £uorescens, Arthrobacter sp., and other Gram-negative rods, form endosulfan diol, not endosulfan sulfate, while the culture pH decreases from 7.3 to values between 4.6 and 5.5. These results suggest that the metabolites of endosulfan and the degradation mechanism might be independent of culture pH.…”

“…(3) Strains K3-3, K3-4, and K3-5 produced endosulfan sulfate as well as endosulfan diol, endosulfan ether and endosulfan lactone, suggesting that these bacteria have oxidation and hydrolysis pathways for endosulfan. (4) No known metabolites of endosulfan degradation were observed in strains Y7-6, Y12-18, Y3-15 and R1-2, whereas unidenti¢ed metabolites were detected by gas chromatography and HPLC. Identi¢cation of these metabolites is under way in our laboratory and further research is necessary to establish the possible endosulfan degradation pathway.…”

“…Endosulfan comprises two parent isomers, K-and L-endosulfan; the K to L ratio of technical endosulfan is about 7:3 [2], and both isomers are extremely toxic to aqueous organisms [3]. Many bacteria and fungi including Corynebacterium sp., Nocardia sp., Mycobacterium sp., Pseudomonas £uorescens, Penicillium sp., Aspergillus sp., Phanerochaete chrysosporium have been reported to be endosulfan degraders [4,5]. Endosulfan could degrade by attack at the sul¢te group by oxida-tion and/or hydrolysis to form the toxic endosulfan sulfate and the non-toxic endosulfan diol, respectively [5,6].…”

Enrichment of a microbial culture capable of degrading endosulphate, the toxic metabolite of endosulfan

“…Previous studies investigating the degradation of endosulfan predominantly describe the formation of endodiol as the initial step in the degradation of endosulfan. This reaction occurs readily under even mildly alkaline conditions (see Martens 1976). Alkaline hydrolysis must have contributed at least in part to the degradation seen in many of these earlier studies and hence, the occurrence of biological hydrolysis to the diol has been over-estimated.…”

Degradation of Organochlorine Pesticides, Particularly Endosulfan, by Trichoderma Harzianum

“…According to the past studies on endosulfan degradation by soil microorganisms [25,26], there are two types of soil fungi to degrade endosulfan; one type of fungi accumulates endosulfan sulfate, and the second type metabolically converts endosulfan sulfate further into endosulfan diol. Although no Trichoderma sp.…”