Biodegradation of diuron by endophytic Bacillus licheniformis strain SDS12 and its application in reducing diuron toxicity for green algae.

The endophytic bacteria live in close nuptial relationship with the host plant. The stress experienced by the plant is expected to be transferred to the endophytes. Thus, plants thriving at polluted sites are likely to harbor pollutant-degrading endophytes. The present study reports the isolation of phenylurea herbicides assimilating Bacillus sps. from Parthenium weed growing at diuron-contaminated site. The isolated endophytes exhibited plant growth-promoting (PGP) activities. Among five isolated diuron-degrading endophytes, the most efficient isolate Bacillus licheniformis strain SDS12 degraded 85.60 ± 1.36% of 50 ppm diuron to benign form via formation of degradation intermediate 3, 4-dichloroaniline (3,4-DCA). Cell-free supernatant (CFS) obtained after diuron degradation by strain SDS12 supported algal growth comparable with the pond water. The chlorophyll content and photosynthetic efficiency of green algae decreased significantly in the presence of diuron-contaminated water; however, no such change was observed in CFS of strain SDS12, thus, suggesting that strain SDS12 can be applied in aquatic bodies for degrading diuron and reducing diuron toxicity for primary producers. Further, the use of PGP and diuron-degrading bacteria in agriculture fields will not only help in remediating the soil but also support plant growth.