Diversity analysis of the largest subunit of the multi-component phenol hydroxylase (LmPH) gene from the phenol degrading microbial communities of an aeration tank of a coking wastewater treatment plant 焦化废水处理厂接触氧化池中降酚菌群的苯酚羟化酶大亚基基因多样性
The diversity of the largest subunit of the multi-component phenol hydroxylase (LmPH) gene in four compartments of the aeration tank (O1-O4) of a coking wastewater treatment plant in Shanghai was analyzed via PCR-TGGE (temperature gradient gel electrophoresis) analysis. TGGE fingerprints were identical in all four compartments, suggesting that the phenol-degrading microbial populations in the different compartments of the aeration tank were highly similar. A LmPH gene clone library from the fourth compartment (O4) was constructed and the nucleotide sequences of 49 randomly selected clones were determined. The 49 clones were classified into 16 groups (amino acid sequences with 100% similarity were defined as one group) based on the deduced amino acid sequences. Five predominant LmPH groups were identified, each of which had more than four clones. Each of the other 11 groups were represented by one clone. Seven LmPH groups had more than 90% similarity with their nearest LmPHs in the GenBank, while 2 groups had less than 80%. Phylogenetic analysis of the partial amino acid sequences of the LmPHs indicated that most of the clones in the library (92%) were affiliated with low-Ks (affinity constants) LmPH, while only one clone (L-SJ32) was affiliated with high-Ks LmPH. These results suggest that LmPH genes were very diverse in the coking wastewater and that the low-Ks LmPHs were the predominant type involved in phenol degradation. Since most of the previously isolated phenol-degrading bacteria had high-Ks LmPHs, this indicates that traditional enrichment culture methods may not have identified the key functional bacteria from this environment.