Faculty Publication (2020)
Accidental fuel oil spills and improper disposal of toxic waste oil into waterways have caused serious pollution problems worldwide. This study is focused on the use of microorganisms and enzymes they produce to address problems of waste oil pollution. Complete genes for enzymes alkane 1-monooxygenase (AlkM) and catechol 1,2-dioxygenase (CatA) implicated in bunker oil degradation were amplified and sequenced from two new strains of Acinetobacter baumannii (S341 and S354) isolated from the polluted Pasig River in the Philippines. Genes for both AlkM and CatA enzymes and predicted proteins exhibited almost identical sequences with the type strain A. baumannii (ATCC 19606). Sequence identity (80%) of alkM genes is lower than the sequence identity (90%) of predicted enzymes between A. baumannii environmental strains and most of the other species under the same genus. Genes for AlkM (or for enzymes with equivalent functions as AlkM like AlkB) and CatA from species that do not belong to the genus Acinetobacter exhibited very low gene and protein sequence identities (49.8–54.6%) with corresponding genes and proteins in strains S341 and S354. Stretches of conserved amino acids in the predicted protein sequences (eight histidine motifs in AlkM/AlkB) and a ferric ion ligated by four amino acids (Tyr164, Tyr200, His224, and His226) in the CatA protein were observed, consistent with previous reports. These conserved regions may be crucial in protein function. The study also reports the successful cloning, in the correct orientation, of complete alkM and catA genes from A. baumannii strains S341 and S354 in pBAD Thio-TOPO plasmid for future expression of the recombinant proteins in non-pathogenic host cells.