Isolation and characterization of triclocarban degrading bacteria as plant growth promoter

Abstract

Triclocarban (TCC) is a widely used as antimicrobial agent in household products. High usage volume of TCC results in its accumulation in sludge and lead to contamination in environments. Application of biosolid in agricultural activities leads to contamination of TCC in agricultural areas. So. development of bioremediation technique for TCC is necessary to maintain quality of agricultural ecosystem. For that purpose, this research isolated 5 soil bacteria capable of TCC degradation and with plant-growth promoting (PGP) activities including Ochrobactrum sp. MC22, Ochrobactrum sp. MC35, Sphingobacterium sp. MC43, Pseudomonas sp. MS45, and Pseudomonas fluorescens MC46. Among them, Ochrobactrum sp. MC22 and P. fluorescens MC46 were selected for further studies. The results showed that Ochrobactrum sp. MC22 could degrade TCC under aerobic and anaerobic conditions. It has ability to degrade TCC in a wide range of concentrations from 0.16-30 mg L-1. The analysis of TCC degradation kinetics and degradation pathway revealed that chloroanilines are degradative intermediates, which could be completely metabolized and detoxified as shown by the toxicity test in pot soil experiment using 2 legume plants. In the case of P. fluorescens MC46, not only TCC degradation capability, degradation kinetics, and degradation pathway were analyzed, but it was also developed into a bacterial formula in order to improve its efficiency for TCC degradation and PGP. Moreover, its usage was proven in soil experiment with mung bean plants where the soil was contaminated with TCC. The bioaugmentation of P. fluorescens MC46 formula in to the contaminated soil not only reduced TCC by 74-76% of its initial concentration, mitigated TCC toxicity, promoted plant growth, but it also improved soil quality with increasing soil enzyme activities. In conclusion, this study demonstrated the potential use of Ochrobactrum sp. MC22 and P. fluorescens MC46 for bioremediation of soil contaminated with TCC as well as chloroanilines, while they could promote plant growth.