The metabolism of carbaryl by three bacterial isolates, Pseudomonas spp. (NCIB 12042 & 12043) and Rhodococcus sp. (NCIB 12038) from garden soil

Abstract

At an alkaline pH and in aqueous solution, carbaryl hydrolyses to form 1-naphthol, methylamine and carbon dioxide, but it is much more stable at an acid pH. Two bacterial isolated from garden soil, Pseudomonas sp. (NCIB 12042) and Rhodococcus sp. (NCIB 12038), could grow on carbaryl as sole carbon and nitrogen source at pH 6.8 but failed to metabolize carbaryl rapidly. Both could use 1-naphthol as sole carbon source and NCIB 12042 metabolized 1-naphthol via salicylic acid which induced higher expression of enzymes in the pathway. Strain NCIB 12038 metabolized 1-naphthol via salicylic and gentisic acids. In contrast, Pseudomonas sp. (NCIB 12043) was selected in a soil perfusion column enrichment at pH 5.2 and metabolized carbaryl rapidly to 1-naphthol and methylamine. 1-Naphthol was metabolized via gentisic acid. Neither salicylate nor gentisate induced higher expression of enzymes for 1-naphthol catabolism in NCIB 12038 and NCIB 12043.