Optimization Process

The optimization of fermentation medium is the most important for obtaining the desired product and many challenges are associated with optimization process. Many techniques are available for optimization of fermentation medium such as borrowing, component swapping, biological mimicry, one factor at a time, factorial design, Plackett and Burman design, central composite design, response surface methodology, evolutionary operation factorial design, artificial neural network, fuzzy logic and genetic algorithms [180]. Production of biocontrol agents is an important step to the commercial use of the product. The development of an economic culture medium is necessary to obtain a high quantity of biomass. The constituents for a medium must satisfy

The method of purification of organic compound depends mainly on the nature of the compound and the impurities present. The factors involve for selecting a particular method of purification are boiling point, melting point, solubility, etc. The various methods of purification are Sublimation, Crystallisation, Distillation, Differential Extraction and Chromatography. Chromatography is an important separation technique used to separate and purify individual chemical compounds from mixtures of compounds. Two methods are generally used to prepare a column, the dry method and the wet method. For the dry method, the column is first filled with dry stationary phase powder. It was followed by the addition of mobile phase and flushed through the column until it is completely wet. For the wet method, silica gel powder is prepared with solvent and then carefully poured into the column. The crude extract in solution is then placed on the top of the packed column material. The small layer of cotton or glass wool is placed to protect the shape of the organic layer from the velocity of the newly added eluent. Then, the eluent is slowly passed through the column. During the entire chromatography process, the eluent is collected in a series of fractions. Fractions can be collected automatically by means of fraction collectors [183]

The most common stationary phase of column chromatography is silica gel, followed by alumina. Other methods are ion exchange chromatography, reversed-phase chromatography (RP) and affinity chromatography or expanded bed adsorption (EBA) chromatography. There is an important ratio between the stationary phase weight and the dry weight of the analyte mixture that can be applied onto the column. For silica column chromatography, this ratio lies within 20:1 to 100:1. The mobile phase or eluent is either a pure solvent or a mixture of different solvents. The eluent has to be selected in different ratios, so that the different compounds can be effectively separated. The eluents is generally optimized using TLC with the same stationary phase. The term preparative HPLC is usually associated with large columns and high flow rates. However, it is not the size of the instrumentation or the amount of mobile phase pumped through the system, but rather the objective of the separation. Preparative HPLC is an expensive technique compared to traditional purification method [184,