Biotransformation of Agricultural Wastes into Lovastatin and Optimization of a Fermentation Process Using Response Surface Methodology (RSM)

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Lovastatin is a competitive inhibitor of the enzyme 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA Reductase). The HMG-CoA reductase is responsible for the production of mevalonate by the reduction of HMG-CoA. It is a rate-limiting step in the production of cholesterol. The current study demonstrates the production of lovastatin from an ethidium bromide mutated strain of Aspergillus terreus ATE-120 (saprophytic fungus) that is grown on 1–3% NaOH pretreated substrate of sugar cane bagasse (Saccharum officinarum L.). For the hyperproduction of lovastatin, different optimization parameters such as temperature, pH, inoculum size, fermentation period, and inoculum age were mentioned and analyzed via response surface methodology. The RSM results indicate that the maximum lovastatin yield (156.43 mg/L) was predicted at a 5.5 pH, 35 °C temperature, 4 mL inoculum size, 36 h inoculum age, and 48 h fermentation via solid state fermentation. According to these results, the effect of pH had a significant effect on lovastatin production, while other parameters had an insignificant effect, and coefficients of determination (R2) having a value of 77.24% indicates the goodness of the proposed model. The structure of the obtained drug was confirmed by nuclear magnetic resonance. Moreover, an X-ray diffraction analysis of the sample was carried out to characterize the physical form of the lovastatin. It can be concluded from the above study that the maximum yield of the drug can be found via RSM and that the selected strain (Aspergillus terreus ATE-120) has good potential for lovastatin production through solid-state fermentation.