Optimization of active composition production from the Antarctic Actinomycete N-1 using Response Surface Methodology

Objective The fermentation conditions of the Antarctic N-1 were optimized to elevate the antibacterial activity of the antibacterial compounds in the fermentation broth.Methods In the present study,using antibacterial activity(agar diffusion method)as index,the medium compositions(source of carbon,nitrogen source,inorganic salt) were investigated to find out the important impact factors.Then Plackett-Burman design(PBD) was employed to find the key ingredients of medium components,and then Box-Behnken design was implemented to determine their optimal concentrations.Result: The optimal medium composition was determined as follows(g/L): millet 12.68,NaNO3 6.67,MgSO4 7H2O 0.31,FeSO4 7H2O 0.03,soybean meal 7.50,CaCO3 0.60,NaCl 2.00,pH = 6.0,temperature 28℃,the rotating speed was 200 r·min-1.This optimization strategy enhanced the production of antibacterial active substances.Compared with the non-optimized fermentation medium,the antibacterial activity increased 5.94 times than that of the non-optimized fermentation medium,at the same time,the weight of mycelium was 1.55 times of the previous.Conclusion The response surface methodology(RSM) model provided an easy and effective way to determine the interactive effect of fermentation conditions on production of antibacterial compounds by N-1.Therefore,the optimized fermentation medium can be applied to produce maximum amounts of antibacterial compounds under laboratory and commercial fermentation conditions,which will facilitate the discovery of new active compounds.