Glucose isomerase production on a xylan-based medium by Bacillus thermoantarcticus

Optimization of Growth Conditions for the Production of Bacillus subtilis Using Central Composite Design and Its Antagonism Against Pathogenic Fungi

Today, the enhancement of spore yields of Bacillus subtilis has considerable interest and has been widely investigated. In this context, studies have been carried out to improve the spore yield as well as the production amount. In order to perform this, optimization studies are conducted for large-scale production of B. subtilis in bioreactors. The prokaryotic structure, high extracellular production potential, lack of pathogenic activity, well-known fermentation technology and short fermentation time are the prominent advantages for the production of B. subtilis in a bioreactor. The Bacillus species produce a wide variety of antifungal and antimicrobial compounds, making them ideal biological control agents. In this study, first, the growth conditions of the medium were investigated and then optimized using the central composite design approach to achieve the highest productivity for the growth of B. subtilis. In the experiments, the effect of temperature of 25, 30 and 35 °C and pH level of 6.0, 7.0 and 8.0 on spore yield was studied. Moreover, the antifungal activity of the B. subtilis culture was investigated against pathogenic fungi: Colletotrichum gloeosporioides, Botrytis cinerea and Aspergillus brasiliensis.

Optimization of Fermentation Medium for the Production of Glucose Isomerase Using Streptomyces sp. SB-P1

The combination of medium ingredients has a profound influence on the metabolic pathways running in the microorganism which regulates the production of numerous metabolites. Glucose isomerase (GI), an enzyme with huge potential in the market, can isomerise glucose into fructose. GI is used widely for the production of High-Fructose Corn Syrup (HFCS). HFCS is used as a sweetener in food and pharmaceutical industries. Streptomyces are well-known producers of numerous enzymes including glucose isomerase. An array of 75 isolates was screened for the production of glucose isomerase. The isolate Streptomyces sp. SB-P1 was found to produce maximum amount of extracellular GI. Sucrose and raffinose among pure carbon sources and corn cob and wheat husk among crude agro residues were found to yield high enzyme titers. Potassium nitrate among pure nitrogen sources and soy residues among crude sources gave maximum production. Quantitative effect of carbon, nitrogen, and inducer on GI was also determined. Plackett-Burman design was used to study the effect of different medium ingredients. Sucrose and xylose as carbon sources and peptone and soy residues as nitrogen sources proved to be beneficial for GI production.