A novel dichloromethane-degrading Lysinibacillus sphaericus strain wh22 and its degradative plasmid

Abstract

Dichloromethane (DCM)-degrading bacterium strain wh22 (GenBank accession number FJ418643) was isolated and identified as Lysinibacillus sphaericus based on standard morphological and physiological properties, cellular fatty acid composition, mole percent guanine-cytosine content, and nucleotide sequence analysis of enzymatically amplified 16S ribosomal deoxyribonucleic acid. The strain also grew on many other halocarbons found in the waste gases of industrial effluents, such as 1,2-dichloroethane, chlorobromomethane, methylene bromide, 1,1,1-trichloroethane, trichloroethylene, and hexachlorobenzene. The strain harbored a novel degradative plasmid, pRC11 (48.8 kb). The genes coding for the metabolism of DCM were found to be plasmid-borne, and a physical map of the plasmid has been established. The purified plasmid was transformed to dcm- Escherichia coli DH5 at a rate of 1.65 x 10(5). The transformed cells were able to grow on DCM at a concentration of 5-16 mM and can be further used as an excellent source for genetic manipulations leading to the construction of genetically modified microbial strains or genetically engineered microorganisms.