Improvement of antibiotic activity of Xenorhabdus bovienii by medium optimization using response surface methodology

Abstract

BackgroundThe production of secondary metabolites with antibiotic properties is a common characteristic to entomopathogenic bacteria Xenorhabdus spp. These metabolites not only have diverse chemical structures but also have a wide range of bioactivities with medicinal and agricultural interests such as antibiotic, antimycotic and insecticidal, nematicidal and antiulcer, antineoplastic and antiviral. It has been known that cultivation parameters are critical to the secondary metabolites produced by microorganisms. Even small changes in the culture medium may not only impact the quantity of certain compounds but also the general metabolic profile of microorganisms. Manipulating nutritional or environmental factors can promote the biosynthesis of secondary metabolites and thus facilitate the discovery of new natural products. This work was conducted to evaluate the influence of nutrition on the antibiotic production of X. bovienii YL002 and to optimize the medium to maximize its antibiotic production.ResultsNutrition has high influence on the antibiotic production of X. bovienii YL002. Glycerol and soytone were identified as the best carbon and nitrogen sources that significantly affected the antibiotic production using one-factor-at-a-time approach. Response surface methodology (RSM) was applied to optimize the medium constituents (glycerol, soytone and minerals) for the antibiotic production of X. bovienii YL002. Higher antibiotic activity (337.5 U/mL) was obtained after optimization. The optimal levels of medium components were (g/L): glycerol 6.90, soytone 25.17, MgSO4·7H2O 1.57, (NH4)2SO4 2.55, KH2PO4 0.87, K2HPO4 1.11 and Na2SO4 1.81. An overall of 37.8% increase in the antibiotic activity of X. bovienii YL002 was obtained compared with that of the original medium.ConclusionsTo the best of our knowledge, there are no reports on antibiotic production of X. boviebii by medium optimization using RSM. The results strongly support the use of RSM for medium optimization. The optimized medium not only resulted in a 37.8% increase of antibiotic activity, but also reduced the numbers of experiments. The chosen method of medium optimization was efficient, simple and less time consuming. This work will be useful for the development of X. bovienii cultivation process for efficient antibiotic production on a large scale, and for the development of more advanced control strategies on plant diseases.

Anti-methicillin Resistant Staphylococcus aureus Compound Isolation from Halophilic Bacillus amyloliquefaciens MHB1 and Determination of Its Mode of Action Using Electron Microscope and Flow Cytometry Analysis

“…Herein, the purified metabolite was isolated from saltpan bacteria and its maximum anti-MRSA activity was attained by optimizing the culture condition in ZMB broth. It has been reported that the culture optimization in media using different parameters including temperature, pH, incubation period, carbon and nitrogen sources influenced the production of the antimicrobial compound [28]. In the current study, the nutritional and environmental parameters were optimized in ZMB medium for the efficient production of anti-MRSA compound.…”

Enhanced candicidal compound production by a new soil isolate Penicillium verruculosum MKH7 under submerged fermentation

“…The predicted data from the model are in agreement with the observed one as is evident from the figure. Figure 4 shows the normal plot of residuals, the linear pattern indicating normality in the error term [24]. A plot of residuals versus the predicted response is shown in Fig.…”

Biological Evaluation of Endophytic Fungus Chaetomium sp. NF15 of Justicia adhatoda L.: A Potential Candidate for Drug Discovery

“…In order to achieve high product yields from the selected NF15 isolate, it was necessary to design a proper production medium for an efficient fermentation process (16, 29). Fungal isolates showed better growth and antimicrobial potential in SDB compared to the other media.…”