Biodegradation of the synthetic pyrethroid insecticide alpha-cypermethrin by Stenotrophomonas maltophilia OG2

A novel gram-negative bacterium, OG2, was isolated from the body microflora of cockroaches (Blatta orientalis). Based on morphological, biochemical, and 16S ribosomal DNA sequence analysis, the isolated strain OG2 was identified as Stenotrophomonas maltophilia. This bacterial strain was screened for its alpha-cypermethrin-degrading potential with minimal salt medium (MSM). The alpha-cypermethrin degradation and utilization ability of the isolated organism was verified. Bacterial growth was measured by optical density in the presence of the pesticide at different concentrations (50-200 mg/L). S. maltophilia OG2 utilized alpha-cypermethrin as the sole carbon source for growth, and alpha-cypermethrin degradation increased when MSM was supplemented with glucose. In the absence and presence of glucose, alpha-cypermethrin (100 mg/L) degradation efficiency of OG2 was 69.9% and 81.3%, respectively. Analysis of the degradation products indicated that S. maltophilia OG2 converted alpha-cypermethrin to 3-phenoxybenzoic acid, 3-phenoxybenzaldehyde, phenol, and muconic acid. Medium composition had considerable influence on the types of metabolic products. According to the results, S. maltophilia OG2 may have potential use in the bioremediation of cypermethrin-contaminated environments.