Degradation of 4-amylphenol and 4-hexylphenol by a new activated sludge isolate of Pseudomonas veronii and proposal for a new subspecies status

Abstract

Novel Pseudomonas strains INA04, INA05, and INA06, were isolated from activated sludge. Strain INA06 was found to degrade long chain alkylphenols such as 4-n-amylphenol and 4-n-hexylphenol as the sole source of carbon, apart from co-metabolic degradation of 4-n-nonylphenol in the presence of phenol, while INA04 and INA05 could grow on phenol, but could not grow well on alkylphenols. Induction studies on strain INA06 revealed a broad substrate-specific phenol hydroxylase, for the metabolism of phenol and alkylphenols, inducible with phenol or para-substituted alkylphenol. They bore close resemblance to members of Pseudomonas sensu stricto. 16S rDNA sequence homology of INA06 was closest to P. veronii (99.7%). DNA-DNA hybridization pointed out higher linkage (64% similarity) to the type strain of P. veronii than to other species of Pseudomonas sensu stricto (>60%). The BOX-PCR profile of all INA strains was similar, but different from that of P. veronii. Since biochemical characteristics were similar to those of P. veronii, and genetic relatedness was at the margin of species differentiation level (70%), we propose these strains to be treated as a new subspecies of P. veronii. The type strain of this new subspecies, named P. veronii subsp. inensis subsp. nov., is strain INA06. The accession number of strain INA05 is CIP 107595=JCM11829, and that of INA06 is CIP107594(T)=JCM11828(T). The 16S rDNA sequence accession number (DDBJ/EMBL/GenBank) of strain INA06 is AB056120.