Efficient phenol degradation by a newly characterized Pseudomonas sp. SA01 isolated from pharmaceutical wastewaters

Abstract

Using the phenol enrichment cultivation method, we succeeded in screening a few bacterial strains with a varied ability for utilizing phenol as the sole carbon source from pharmaceutical disposal wastewaters plant. Among these strains, a potent phenol-degrading bacterium, assigned Pseudomonas sp. SA01, was identified and examined as having the greatest potential for degrading phenol. According to biochemical characteristics and 16S rRNA sequence analysis, the isolate was identified as Pseudomonas sp. The isolated strain started to degrade 0.7 g/l of phenol after an initial very short lag phase, and phenol decomposition was then rapidly completed within 30 h. Pseudomonas sp. SA01 was able to degrade phenol in concentrations up to 1 g/l. Higher phenol concentrations (>1 g/l) had a significant inhibitory effect on bacterial growth. The optimum degradation pH value was found to be 6.5. Addition of mannitol and casein as auxiliary carbon and nitrogen sources enhanced the rate of phenol removal to as low as 20 h. Based on the absorption spectra of catechol bioconversion of phenol-grown cells, it was concluded that the SA01 strain metabolizes the phenol via a meta-cleavage pathway.