Degradation pathways of low-ethoxylated nonylphenols by isolated bacteria using an improved method.
Nonylphenol ethoxylates (NPEOs) with low ethoxylation degree (NPav₂EO; containing two ethoxy units on average) and estrogenic properties are the intermediate products of nonionic surfactant NPEOs. To better understand the environmental fate of low-ethoxylated NPEOs, phylogenetically diverse low-ethoxylated NPEO-degrading bacteria were isolated from activated sludge using gellan gum as the gelling reagent. Four isolates belonging to four genera, i.e., Pseudomonas sp. NP522b in γ-Proteobacteria, Variovorax sp. NP427b and Ralstonia sp. NP47a in β-Proteobacteria, and Sphingomonas sp. NP42a in α-Proteobacteria were acquired. Ralstonia sp. NP47a or Sphingomonas sp. NP42a, have not been reported for the degradation of low-ethoxylated NPEOs previously. The biotransformation pathways of these isolates were investigated. The first three strains (NP522b, NP427b, and NP47a) exhibited high NPav₂EO oxidation ability by oxidizing the polyethoxy (EO) chain to form low-ethoxylated nonylphenoxy carboxylates, and then further oxidizing the alkyl chain to form carboxyalkylphenol polyethoxycarboxylates. Furthermore, Sphingomonas sp. NP42a degraded NPav2EO through a nonoxidative pathway with nonylphenol monoethoxylate as the dominant product.
State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085, China.
Yu
Y
Zhang
Xin
X
Gu
Jing
J
Zhang
Min
M
Yang
D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001711:Biotransformation; D010636:Phenols / Q000737:chemistry / Q000378:metabolism*; D010802:Phylogeny; D012722:Sewage / Q000382:microbiology; D013501:Surface-Active Agents / Q000378:metabolism
D010636:Phenols; D012722:Sewage; D013501:Surface-Active Agents