Characterisation of Bacillus strains from volcanic area Gunung Sibayak able to degrade 2,2- dichloropropionic acid

Abstract

Halogenated compounds are mainly found in agricultural area. The problem arose because these compounds
are toxic to human and are persistent in environment. The aim of the present study was to isolate 2,2-
dichloropropionic acid (2,2-DCP) degrading bacteria that can grow at higher temperature rather than at normal
25 to 30°C temperature. A soil bacterium was isolated from the surrounding volcanic area at the feet of Gunung
Sibayak, Indonesia using streak plate method. The sample was repeatedly streaked onto 20 mM of 2,2-DCP to
get a pure culture. The culture was incubated for 2 days at 30, 40 and 60°C incubator shaker aerobically. The
isolated bacterium grew best at 40°C but failed to grow at 60°C. Based on partial 16S rDNA gene sequence, the
isolated strain GS1 showed high sequence identity to Bacillus megaterium strain 0 to 2, whereas, using
biochemical tests suggested that the genus belongs to Bacillus sp. as expected. Strain GS1 was a Gram
positive, rod in shape and produced spore. The results also suggested that, strain GS1 could degrade 20 mM
(2,2-DCP) based on growth experiment. In conclusion, the molecular method identified Bacillus genus showing
no discrepencies from the biochemical test results. This is the first report of Bacillus strains associated with
2,2-DCP degradation using above normal temperature for growth.