Diversity of octylphenol polyethoxylate-degrading bacteria: With a special reference to Brevibacterium sp. TX4

Octylphenol polyethoxylates (OPEO_n) are surfactants and prone to degradation into xenoestrogenic metabolites, polluting various environments. We sought to identify bacterial strains and potential metabolic pathways involved in OPEO_n degradation. By enrichment culture, a greater diversity of bacterial strains was noted in a green house of pesticide factory, which had frequently sprayed by different formulated pesticides, compared to a rice field and a drainage ditch (32:6:5). These bacteria grew on OPEO_n as the sole carbon source; seven genera had not been previously reported, of which only Brevibacterium was Gram-positive. Metabolic analysis by HPLC/MS revealed that Brevibacterium sp. TX4 could shorten the ethoxylate chain thereby degrading OPEO_n, during which O₂ was required. Hence, with frequent spray of pesticides formulated with anionic surfactants such as OPEO_n could increase the diversity of OPEO_n-degrading bacteria. Brevibacterium sp. TX4 is the first Gram-positive bacterium which was demonstrated to shorten the ethoxylate chain of OPEO_n.