Profile of a Nonylphenol-Degrading Microflora and Its Potential for Bioremedial Applications

Abstract

Nonylphenol (NP) is an important intermediate in the production of various commercial and industrial materials, but is also known as a ubiquitous pollutant in urban aquatic environments. We recently studied the NP-degrading activities of microflora in several aquatic environments, and found a notable degrading activity for wastewater from a sewage treatment plant in Tokyo. This result led us to isolate NP-degrading microbes and identify biodegradation products. Using conventional plate culture techniques and molecular biological methods, Pseudomonas and Sphingomonas species, which are known for their degradation activities of many aromatic compounds, have been isolated. But it has also been found that Sphingomonas sp. (S-strain) is necessary and sufficient for the degradation of NP. Although the role of Pseudomonas sp. (P-strain) remains unclear, P-strain seems to provide some co-nutrients for the growth of S-strain. The degradation products were analyzed by GC/MS and NMR. More than 95% of NP was degraded within 10 days and aromatic compounds other than NP were not found, suggesting that the phenolic part of NP was completely degraded. We also examined the potential of S-strain for bioremedial applications. S-strain cells immobilized on chitosan or alginate beads retain their NP-degrading activity in flask-scale experiments. Furthermore, the chitosan-bound cells in a lab-scale bioreactor have been found to be persistent for repeated use, suggesting that S-strain is applicable to the treatment of NP-contaminated wastewater.

Organic Nutrient-dependent Degradation of Branched Nonylphenol by Sphingomonas sp. YT Isolated from a River Sediment Sample.

“…In contrast to the NP-degrading isolates of Tanghe et al 30) and Fujii et al 6) , our isolate showed no significant growth and degraded NP in a chemically defined medium with NP as the sole energy and carbon source. We also present gas chromatography-mass spectrometric data concerning the initial attack on the NP molecule by our isolate.…”

“…In addition, strain YT seems to be more sensitive to NP than strain TTNP3 and S. cloacae JCM 10874. The batch cultures of strain TTNP3 30) and S. cloacae JCM 10874 6) were grown with 600 to 1,000 ppm of NP. In the case of strain YT, the suppressive effect of NP, affecting the lag-phase and the mmax, was found at 100 ppm of NP (Fig.…”

“…This feature is known to hamper microbial degradation 16,17) . Recently Tanghe et al 30) and subsequently Fujii et al 5,6) described the isolation of Sphingomonas strains able to grow on a commercial mixture of branched NP isomers as a sole carbon and energy source in pure culture. Until now, there have been only vague indications as to how branched NP molecules are attacked by bacteria 6,13,30) .…”

Cyclodextrin-linked alginate beads as supporting materials for Sphingomonas cloacae, a nonylphenol degrading bacteria

“…All other chemicals used were of reagent grade. S. cloacae (Fuji et al, 2000) was purchased from Japan Collection of Microorganisms, Riken Bioresource Center (Saitama, Japan); catalog number 10874. The stock cultures were stored at 4 °C in nutrient agar.…”

“…Although nonylphenol is recalcitrant in nature, its bioavailability has triggered extensive studies on its bio-remediation by use of some yeast and gram-negative bacteria. Candida aquaetexotoris was reported to decompose the alkyl chain of nonylphenol to give 4-acetylphenol (Vallini et al, 2001), while several bacteria such as Sphingomonas xenophaga (Gabriel et al, 2005), Sphingomonas cloacae (Fuji et al, 2000), and Sphingobium amiense (Ushiba et al, 2003) metabolized its aromatic moiety to the corresponding C9 alcohols.…”