Ecotoxicity by the biodegradation of alkylphenol polyethoxylates depends on the effect of trace elements.

The bacteria Sphingomonas sp. strain BSN22, isolated from bean fields, degraded octylphenol polyethoxylates (OPEOn) to octylphenol (OP) under aerobic conditions. This biodegradation mechanism proceeded by the following two-step degradation process: (1) degradation of OPEOn to octylphenol triethoxylate (OPEO3), (2) degradation from OPEO3 to OP via octylphenoxy acetic acid (OPEC1). The chemical structure of OPEC1 was confirmed by analysis using O-18-labeled water. Quantitative studies revealed that magnesium (Mg2+) and calcium (Ca2+) ions were essential for the biodegradation of OPEOn. Furthermore, the rate of biodegradation was especially accelerated by ferric ions (Fe3+), and the accumulated amounts of endocrine active chemicals, such as OP, OPEO1, and OPEC1, significantly increased to the concentration of 22.8, 221.7, and 961.1 mu M in the presence of 37.0 mu M Fe3+, respectively. This suggests that environmental elements significantly influence the resultant ecotoxicity as well as the rate of their biodegradation in the environment. This study on the mechanism of OPEOn biodegradation may play an important role in understanding and managing environmental safety, including drinking water safety.