INVESTIGATION OF OPTIMAL CONDITIONS FOR THE PRODUCTION OF POLY GAMMA GLUTAMIC ACID (Γ -PGA) FROM A LOCAL ISOLATE OF THE BACILLUS MEGATERIUM

This study involved the production of poly-γ-glutamic acid (γ-PGA) using a local isolate of the Bacillus megaterium bacteria. Two natural carbon sources were used for qualitative detection and quantitative estimation using thin layer chromatography [TLC]. The study also evaluated its ability to grow in a production medium and improve productivity by manipulating its components and environmental conditions using molasses (sugarcane), corn syrup, glucose, fructose, sucrose, and some sources of nitrogen. The best sources and optimal concentrations of carbon and nitrogen were selected. The optimal conditions for production of γ-PGA were by using a semi-synthetic medium by preparing the molasses as a carbohydrate source at 10% concentration, while ammonium nitrate provided the best source of nitrogen at 2%. This study showed that the optimum temperature and initial pH for achieving better γ-PGA productivity from the studied bacteria was at 37ᵒ C and 6.5, respectively. Higher productivity was achieved by agitation and aeration at a ratio of 5:1 of the fermentation media size to flask volume in the rotary shaker incubator at 180 rpm/min, using an inoculum size of 2.8×106 cfu/mL in the production medium till the total γ-PGA concentration reached 7.22 mg/ml. The γ-PGA was then extracted from a productive medium after precipitation and obtaining pure crystals, and its purity determined using Fourier-Transform Infrared Spectroscopy (FTIR)