Klebsiella aquatica sp. nov., a Novel PAH Degrading Bacterium from Wastewater

Environmental pollution has become one of the most prominent problems in the world. In the present study, a PAH pollutant degrading bacterium NAPL was isolated from the activated sludge of a wastewater treatment plant in Zibo city, China, with the selective naphthalene-mineral salts medium. Morphological studies revealed NAPL was a short-rod gram negative bacterium. Physiological and biochemical experiments showed that NAPL shared some common properties with members of Klebsiella, such as being facultative anaerobic, not mobile, cytochrome oxidase negative, fermenting a wide range of organics, etc. Besides, NAPL exhibited some unordinary properties such as producing both acid and acetylmethyl carbinol from MR-VP broth, and being arginine dihydrolase positive. Then, the genomic DNA of NAPL was extracted and its 16S ribosome RNA gene was cloned and sequenced. The GenBank accession number for the sequence was HM593519. Basing on the sequence and other related sequences in the GenBank database, an alignment was conducted then a phylogenetic tree was constructed with DNASTAR lasergene software. The results indicated that NAPL was located in the lineage of Klebsiella. NAPL, together with unnamed strains K. sp LP1MK and K. sp GR9, constructed a novel divarication, which shared homology with the known species K. pneumoniae, K. terrigena and K. plantica at a level of 98%, 97%, and 97% identity respectively. At the same time, it shared lower homology with other genera. All the above mentioned data supported that NAPL represented a new species of Klebsiella, K. aquatica, sp. nov. This was the first report about Klebsiella degrading polycyclic aromatic hydrocarbon. It would guide the application of the bacterium to eliminate environmental pollutants.