Aerobic reduction of perchlorate by bacteria isolated in Kerala, South India

Possibility of perchlorate reduction by microbes raises hope for an eco-friendly mode of degradation of this toxic rocket fuel. This study reports 3 isolates (A1, A2 and A3) capable of molybdenum-independent degradation of perchlorate under aerobic conditions. The rate of degradation was the highest when perchlorate concentration was 17 mM, and then 3.2 mM, 4.7 mM and 4.1 mM of perchlorate was reduced by isolates A1, A2 and A3 (respectively) after 72 h at 28 degrees C under aerobic conditions. Presence of perchlorate at a concentration higher than 17 mM resulted in some inhibition of perchlorate reduction. 16S ribosomal RNA gene analysis revealed isolate A1 to be Pseudomonas stutzeri (Proteobacteria) while isolates A2 ad A3 where found to belong to the genus Arthrobacter (Actinobacteria). The study, apart from demonstrating ribotyping as a rapid method of identification of economically important soil microbes, also raised prospects for using artificial consortia for environmental degradation of perchlorate, without apparent domination of Dechloromonas spp. (a group of microbes known for perchlorate remediation in the environment).