Author : Edwin Thomas Apituley* and Amos Killay
Molecular sequence data analysis become important tool to inferred evolutionary relationship and systematic ordering among among organism. It complementing traditional method such as comparison of morpholocical and biochemichal characteristics. In this article, three genes sequnces encoding RNA polymerase subunits and 16S rRNA gene sequence are discussed for their evolutionary relationship among species of Rhodobacter, a genus of phototrophic α-proteobacteria, and between Rhodobacter species and several reference microorganism. Level of sequence identity among gene sequence showed the lowest variation was in 16SrRNA gene sequences, and the the highest was in rpoD gene sequence. Phylogenetic tree constructions were done using Neighbour joining method and Kimura – 2 Parameter model to measure genetic distance. Bootstrap analysis was also applied with 1000 repeats. Members of Rhodobacter genus were divided into two major clusters based on phylognetic analysis of 16S rRNA gene sequence. There is ambiguity of Pararhodobacter sp. CCB-MM2 position between anlysis based on 16SrRNA gene sequnce and rpo gene sequences where analysis based on rpo genes sequences able to locate Pararhodobacter sp. CCB-MM2 on its own phylognetic tree branch, separated from cluster of Rhodobacter species. Key words: Rhodobacter, phylogenetic analysis, 16S rRNA, rpoB, rpoC, rpoD.
Dr. Arend L Mapanawang, Sp.PD, FINASIM, PhD