Enhanced ciprofloxacin removal by plant growth-promoting Microbacterium sp. WHC1 in presence of Eichhornia crassipes root exudates

Abstract

Antibiotics are released undegraded or partially degraded in the environment which renders them difficult for bioremediation, therefore creating a major threat to antibiotic pollution. Ciprofloxacin (CIP) is a fluoroquinolone that is highly persistent and refractory to degradation. The current study aims to isolate and characterize the CIP resistant, rhizospheric bacteria from Eichhornia crassipes, to assess the effect of root exudates on CIP removal. Also, the plant growth-promoting (PGP) traits of the isolated bacteria were evaluated in the absence and presence of CIP. The enrichment technique in M9 minimal media was used for the isolation and bacteria was identified as Microbacterium sp. WHC1. E.crassipes was able to remove 78% of CIP from Hoagland media. However, the maximum removal was seen in presence of the root exudates and bacterial isolate WHC1 (98%). In-vitro screening of the bacteria was done for studying the PGP traits. Microbacterium sp. WHC1 showed positive results for ammonia and Indole-3-acetic acid (IAA) production, whereas negative results were obtained for hydrogen cyanide (HCN) production and phosphorous (P) solubilization. The current study findings can help in understanding the interactions between the rhizoplane bacteria and root exudates which helps in the decontamination of pollutants. PGP activities of these isolates could be a strategy to improve large scale polluted sites using green and eco-friendly technology.