Eco-friendly biotransformation of penicillin G by free and immobilized marine halophilic Bacillus pseudomycoides AH1

Abstract

Several antibiotics are partially metabolized by patients after administration and end up in municipal sewage systems. The fate of biodegradation in aquatic environments and the role of biodegradation in the development of bacterial resistance are poorly understood. Thus, as a crucial step in an environmental risk assessment, the biodegradability of many therapeutically significant antibiotics was investigated. A marine halophilic bacteria that degrades penicillin G (PEN-G) was isolated and identified based on morphology, physio-biochemical characteristics, and 16S rDNA sequences as Bacillus pseudomycoides AH1 (accession no. MF037698). The effects of various concentrations of PEN-G and carbon and nitrogen sources on the biotransformation ability at 30°C and pH 7.0 were evaluated. Cells grown in medium supplemented with glucose as an additional carbon source and yeast extract as a nitrogen source exhibited maximal PEN-G biotransformation efficiency and rate (71.678% ±1.28 and 2.99 mg/h, respectively). The culture conditions for B. pseudomycoides AH1 cells were optimized using a Plackett–Burman design (PBD). Six key determinants (p < 0.05) significantly affected the process outcome, as deduced by regression analysis of the PBD data, and modified MSM broth achieved PEN-G biotransformation efficiency (100%) under aerobic shaking conditions at 35°C, irrespective of HPLC analysis. Additionally, the present investigation could strongly support the application of immobilization approaches for the removal of PEN-G-contaminated environmental sites. To the best of the authors’ knowledge, this is the first detailed study on the efficient biotransformation of PEN-G by an alginate-bacteria system as a simple, green, and inexpensive process, as well as a promising method.