Enrichment and characterization of bacterial consortia for degrading 2-mercaptobenzothiazole in rubber industrial wastewater

Abstract

© 2020 Elsevier B.V. Benzothiazoles especially 2-mercaptobenzothiazole (2-MBT) in rubber industrial wastewater can be released into the environment. They can cause adverse health impacts. This study aimed to obtain efficient 2-MBT-degrading bacteria for wastewater application. The bacterial consortia were enriched by incubating rubber wastewater sludge in a medium containing 2-MBT for 28 days. Stepwise acclimatization was conducted with increasing 2-MBT concentrations from 50 to 200 mg L−1 in nitrogen-containing medium for 76 days. The process significantly increased the bacterial number and changed the dominant populations. Among these consortia, the EN consortium from benzothiazole-containing sludge had the highest specific 2-MBT biodegradation rate of 5.2 ± 0.5 mg L−1 day−1 mg protein-1 and could degrade up to 300 mg L−1 2-MBT. From 16S rRNA gene analysis, Pseudomonas was the dominant genus at approximately 70 % of the total population. Stenotrophomonas was the second most abundant populations and have never been reported for 2-MBT biodegradation. The EN consortium removed 65–79 % and 90–93 % of 112 mg L−1 2-MBT and ∼4000 mg L−1 COD in rubber wastewater, respectively, which were significantly higher than the values of natural attenuation. Therefore, the EN consortium could be an ideal inoculum for the post-treatment of benzothiazoles in rubber industrial wastewater.