Complete Degradation and Detoxification of Ciprofloxacin by a Micro-/Nanostructured Biogenic Mn Oxide Composite from a Highly Active Mn2+-Oxidizing Pseudomonas Strain

Abstract

Ciprofloxacin (CIP), as a representative broad-spectrum antibiotic, poses a major threat to human health and the ecological environment as a result of its abuse and emissions. In this study, a highly active Mn2+-oxidizing bacterium, Pseudomonas sp. CCTCC M2014168, was induced to form micro-/nanostructured biogenic Mn oxide (BMO) aggregates through continuous culturing with 1 mmoL−1 Mn2+. Following the characterization of Mn4+ oxides and the micro-/nanostructures by scanning electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction assays, the BMO composites were subjected to CIP degradation and detoxification in laboratory trials. High-performance liquid chromatograph (HPLC) analysis identified that the BMO composites were capable of completely degrading CIP, and HPLC with a mass spectrometer (LC/MS) assays identified three intermediates in the degradation pathway. The reaction temperature, pH and initial ciprofloxacin concentration substantially affected the degradation efficiency of CIP to a certain extent, and the metal ions Mg2+, Cu2+, Ni2+ and Co2+ exerted significant inhibitory effects on CIP degradation. A toxicity test of the degradation products showed that CIP was completely detoxified by degradation. Moreover, the prepared BMO composite exhibited a high capacity for repeated degradation and good performance in continuous degradation cycles, as well as a high capacity to degrade CIP in real natural water.

Cobalt-substituted ZnS QDs: a diluted magnetic semiconductor and efficient photocatalyst

“…When released into the environment untreated, CIP can also act as a pollutant. [1][2][3][4][5][6][7][8] The physicochemical characteristics of CIP are presented in Table S1 (ESI section). † Co-doped ZnS QDs were employed in the photocatalytic experiments to degrade CIP in water solutions.…”

“…Antibiotic contamination in wastewater and the environment can be reduced effectively via photocatalytic degradation when appropriate nanocatalysts are used. [4][5][6][7][8] In this direction, nanosized II-VI semiconductors have attracted much attention from researchers due to their unique physical characteristics and adequate optical bandgap, which endow them with effective photocatalytic activities. Among all other available semiconductors, zinc sulphide (ZnS) is the most interesting II-VI semiconductor owing to its stable cubic zinc blende crystal structure.…”

Response Surface Methodology for Optimization of Operational Parameters To Remove Ciprofloxacin from Contaminated Water in the Presence of a Bacterial Consortium

“… 33 Analyses of degradation intermediates by HPLC and liquid chromatography/mass spectrometry suggested that 100% of CFX could be removed from water due to complete microbial degradation. 34 …”

“…The biodegradation of CFX likely started from the cleavage of isoxazole and piperazinyl rings catalyzed by sulfite reductase and cytochrome P450 (CYP450) enzymes, respectively . Analyses of degradation intermediates by HPLC and liquid chromatography/mass spectrometry suggested that 100% of CFX could be removed from water due to complete microbial degradation …”

“…33 Analyses of degradation intermediates by HPLC and liquid chromatography/mass spectrometry suggested that 100% of CFX could be removed from water due to complete microbial degradation. 34 Optimization of Parameters for CFX-Biodegradation. RSM was used to investigate the interaction and concurrent effects of four variables, namely, pH, temperature, inoculum size, and CFX concentration on the biodegradation of CFX.…”