Microbial degradation of phenanthrene by addition of a sophorolipid mixture

Citation
C. Schippers et al., Microbial degradation of phenanthrene by addition of a sophorolipid mixture, J BIOTECH, 83(3), 2000, pp. 189-198
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biotecnology & Applied Microbiology",Microbiology
Journal title
JOURNAL OF BIOTECHNOLOGY
ISSN journal
0168-1656 → ACNP
Volume
83
Issue
3
Year of publication
2000
Pages
189 - 198
Database
ISI
SICI code
0168-1656(20001013)83:3<189:MDOPBA>2.0.ZU;2-K
Abstract
The influence of sophorolipidis on microbial degradation of poorly soluble phenanthrene in liquid and soil suspension culture was evaluated in the wor k presented. Experiments were carried out in two parts. In the first part, important basic physico-chemical characteristics of the biosurfactant and t he pollutant used were determined. The critical micelle concentration (CMC) and the solubilization ratio of the biosurfactant were found to be in a go od range compared with synthetic surfactants. Also, a reduction to 71% of t he detectable amount of phenanthrene was measured within 4 d in soil suspen sion without any biotic influence. In the second part, culture experiments were done with Sphingomonas yanoikuyae, the bacterium used throughout the w ork presented here with the aim to assess the toxicity of the sophorolipids on these bacteria and the effect of the surfactant on biodegradation. In e xponential growth tests, no toxicity up to 1 g 1(-1) sophorolipids could be detected, whereas in an agar plate test. slight growth hindrance was measu red at a lower concentration of 250 mg 1(-1) The above mentioned data were important for planning further experiments. In the following cultivations w ith liquid and soil suspension media, enhancements of the biodegradation wi th surfactant addition were measurable. Fluorescence measurements showed th at this effect was not due to an increasing biomass, but to an augmentation of bioavailability of the phenanthrene through increasing the apparent dis solved pollutant. Surfactant addition had the consequence of decreasing the residual detectable pollutant concentration (after 36 h 0.5 compared with 2.3 mg 1(-1) soil suspension) and increasing the maximal degradation rate ( 127 instead of 80 mg 1(-1) soil suspension x 10 h). Therefore, the two main problems of biological soil remediation techniques, longer process time an d residual pollutants, may be solved by the use of surfactants. (C) 2000 El sevier Science B.V. All rights reserved.