Optimization of fermentation conditions for production of bioactive metabolites effective against Staphylococcus epidermidis by a newly isolated Nocardiopsis chromatogenes strain SH89 using the response surface methodology

Abstract

The genus Nocardiopsis, a widespread group in phylum Actinobacteria, has received much attention owing to its ecological diversity and ability to produce a rich array of bioactive metabolites. Nocardiopsis sp. strain SH89 was isolated from soil sample collected from Borg El Arab city, Alexandria, Egypt and tested for its ability to produce bioactive compounds. According to the cultural, morphological, biochemical characteristics and 16S rRNA sequencing, the isolated strain is identified as Nocardiopsis chromatogenes strain SH89 and its sequencing product was deposited in the GenBank database under accession number KT236083. The Plackett-Burman statistical design was used for initial screening of fifteen different factors for their significance on bioactive metabolites production by Nocardiopsis chromatogenes strain SH89. Among the variables screened, KNO3, medium volume and agitation speed had significant effects on bioactive metabolites production. The levels of these significant variables and their interaction effects were optimized by Box-Behnken statistical design. An overall one-fold increase in the production of antimicrobial metabolites was achieved after optimization by using response surface methodology compared with that obtained in the un-optimized medium. This study points the success of statistical model in developing an optimized production medium for enhanced antibacterial compound production by Nocardiopsis chromatogenes strain SH89.