BIODEGRADATION OF COMMERCIAL LINEAR ALKYL BENZENES BY NOCARDIA-AMARAE

Laboratory degradation studies of two indigeneously produced linear al kyl benzenes by Nocardia amarae MB-11 isolated from soil showed an ove rall degradation of linear alkyl benzenes isomers to the extent of 57- 70%. Degradation of 2-phenyl isomers of linear alkyl benzenes was comp lete and faster than that of other phenyl position (C3-C7) isomers whi ch were degraded to the extent of 40-72% only. Length of alkyl side ch ains (C-10-C-14) had little or no impact on the degradation pattern, M ajor metabolities detected were 2-, 3- and 4-phenyl butyric acids, phe nyl acetic acid and cis,cis-muconic acid. Minor metabolites were trans -cinnamic acid, 4-phenyl 3-butenoic acid and 3-phenyl pentanoic acid a long with two unidentified hydroxy acids, On the basis of the formatio n pattern of these metabolities, three catabolic pathways of linear al kyl benzenes isomers in Nocardia amarae MB-11 were postulated. All the phenyl position (C2-C7) isomers of C-10, C-12 and C-14 linear alkyl b enzenes along with 3-phenyl and 5-phenyl isomers of C-11 and C-13 line ar alkyl benzenes were degraded via cis,cis-muconic acid pathway, Othe r phenyl position isomers of C-11 and C-13 linear alkyl benzenes with phenyl substitution at even number carbon atoms mere principally degra ded via phenyl acetic acid pathway while trans-cinnamic acid formation provided a minor pathway.