Identification of serratia marcescens se1 and determination of its herbicide 2,2-dichloropropionate (2,2-dcp) degradation potential

Aims: The goal of the study is to isolate species of bacteria that capable of utilizing 2,2-dichloropropionic acid (2,2-DCP) as sole carbon source from soil sample collected from surrounding lake water located in Universiti Teknologi Malaysia, Skudai, Johor. Methodology and Results: Genomic DNA from bacterium SE1 was extracted and PCR amplification was carried out using universal primers, Fd1 (5' - AGA GTT TGA TCC TGGCTC AG - 3') and rP1 (5'- ACG GTC ATA CCT TGT TAC GAC TT - 3') before sending for sequencing. The 16S rDNA nucleotide sequences were compared with Basic Local Alignment Search Tool nucleotide (BLASTn) and further analyzed using phylogenetic tree of Neighbour-Joining method (MEGA 5). Phylogenetic analysis indicated that SE1 strain clearly shared 97% homology to the genus of Serratia marcescens and therefore designated as Serratia marcescens sp. SE1. SE1 exhibited the ability to utilize 2,2-DCP as sole carbon source at 20 mM concentration with cell doubling time of 5 h and maximum chloride ion release of 38 μmolCl-/mL. This result suggests that the dehalogenase enzyme present in the bacteria has high affinity towards the substrate. Based on morphological and partial biochemical characteristics, strain SE1 was a non-motile Gram negative bacterium with red colonies, that gave a catalase positive reaction. Conclusion, significance and impact of study: A better understanding of dehalogenases enzyme produce by this S. marcescens sp. SE1 in general will be useful to be used as bioremediation tools for environmental management. This is the first reported case that Serratia sp. has the ability to degrade halogenated compound