Consumption of Ciprofloxacin as the sole Carbon and energy source and Phenomenal Transformation to a Culturable nanometer-sized- bacterium demonstrated by a hospital-waste-water isolate Klebsiella&nbsp sp. SG01

Antimicrobial resistance is a global crisis. Biodegradation by bacteria is an effective strategy to remove the micropollutant from the environment. In this study, we demonstrate that a persistent fluoroquinolone, ciprofloxacin (CIP) can be degraded by a multidrug-resistant Klebsiella sp. SG01 and used as its only carbon source. The degradation was quantified using UV-vis spectroscopy and the degraded product was less toxic than the parent compound as tested against a susceptible Escherichia coli K12. SG01 changes into nano-sized cells as culturable nanobacterium, passes through a 0.22 m pore-size filter while growing on ciprofloxacin, and shows a shorter generation time than cells grown on glucose or rich medium. The basis for the changed growth phenotype of nano-SG01 cells and metabolic changes was partially established by the whole-genome transcriptome. ImportanceFluoroquinolones (FQs) constitute a class of persistent antimicrobials, having a high affinity for sludge, sediments, and soil with reported half-lives of 10.6 days in surface waters and up to 580 days in soil matrices. However, more than 50% consumption or degradation of CIP at higher concentration ([~]2g/L) within 48 hours is not yet reported. Also, the isolate transforms into a nano-form to consume the antibiotic and economizes its metabolism to degrade CIP. From the One Health Approach perspective, nanobacterial transformation is an alarming concern as such viable nanobacteria continue to proliferate and may trigger infection in host. The strategy should be to utilize this powerful strain for the biodegradation of CIP.