Identification and fermentation optimization of a myxobacterium producing anti-MRSA bioactive products

Objective In this report, strain GIM1.813 was investigated, prepared for future isolation and identification of anti-methicillin-resistant Staphylococcus aureus (MRSA) bioactive products.

Method According to colonial morphology, scanning electron microscopy, physiological and biochemical characteristics, and phylogenetic analysis based on 16S rRNA genes, GIM1.813 was identified and classified. The effects of seven mediums on the active compounds producted by strain GIM1.813 were compared. The chosen medium and fermentation conditions were optimized by orthogonal experiments.

Result The optimal pH and temperature for strain GIM1.813 were 7.0 and 30.0 ℃, respectively, and the strain could tolerate up to 10 g·L^-1 NaCl. The data of physical-chemical characteristics, chromosomal DNA G+C concents and quinines of this strain were also presented. Strain GIM1.813 grew well in all seven tested mediums, while it produced metabolites with the maximum antibacterial activity in IVY/2 medium. After fermentation optimization, the anti-MRSA activity of fermentation broth increased by 49.12% and the strain GIM1.813 grew better.

Conclusion Strain GIM1.813 was classified as Corallococcus exiguous. Its ability of producing anti-MRSA bioactive components was improved significantly by fermentation optimization. Meanwhile, Mg²⁺ and starch were found to significantly improve the ability of myxobacteria to produce bioactive components.