Insights on marine Streptomyces derived kalafungin with beta lactamase inhibition potential and its antiStaphylococcal infection studies in zebrafish model

Abstract

and#946;-lactamase inhibitors are potent synergistic drugs to deteriorate newlinethe multidrug-resistant bacteria. The present study was aimed to isolate newlineand characterize and#946;-lactamase inhibitory compounds from marine newlineactinobacteria and its in vivo anti-infection studies in zebrafish model. A newlineand#946;-lactamase inhibitory compound was isolated from marine sponge newlinederived Streptomyces sp SBRK1. Further and#946;-lactamase inhibitory assay newlineguided purification yielded the active compound at the retention time of newline28.64 min through high performance liquid chromatography and was newlinesuccessfully identified as kalafungin by LC-MS based dereplication newlineanalysis. newlineThe IC50 was calculated with log inhibition concentration versus newlinepercentage of inhibition and the IC50 value of inhibitor kalafungin was newlinefound to be 225.37 ± 1.95 and#956;M, while compared with the commercial newlineinhibitors clavulanic acid showed 137.42 ± 0.67 and#956;M. The kinetic newlineanalysis showed the Km value of 3.448 ± 0.7 and#956;M and Vmax value of newline215.356 ± 8 and#956;M/min uncompetitive mode of inhibition. newlineThe efficacy studies based on scanning electron microscopy and newlineatomic force microscopy imaging studies revealed that S. aureus treated newlinewith kalafungin in the presence of penicillin affected the cell surface. newlineFurther, kalafungin evidently inhibited the biofilm formation by S. newlineaureus at its sub-MIC concentration. Molecular docking studies have newlineconfirmed the binding property of kalafungin with and#946;-lactamase with two newlinehydrogen bonds and the binding affinity of the complex is newline- 8.5 Kcal/mol. Maximum production of kalafungin under solid state newlinefermentation conditions were achieved through fractional factorial newlineviii newlinedesign and the optimum medium composition by Response Surface newlineMethodology (RSM). Plackett Burman design and Box Behnken newlinedesign experiments have given the maximum production of 51.4 mg/L newlineof kalafungin at 29°C for 8 days of incubation which is 25.06% more newlinethan the unoptimized conditions. newlineThe infection establishment by microinjection and bath newlineimmersion was successfully employed in zebrafish embryos and the newlineanti-infection prop