Feasibility of the bio-conversion of hydrocarbon feedstock to citric acid.

Abstract

It is the focus of this study to examine the feasibility of using hydrocarbon oils as the sole source of carbon for the production of citric acid and biomass. Initial lab experiments were conducted using 1875 ml batch flask fermentations to determine the yeast strain of Candida lipolytica and hydrocarbon feedstock of choice. The two yeast strains investigated were Candida lipolytica NRRL-Y-1094 and Candida lipolytica NRRL-Y-1095. The two feedstocks evaluated were kerosene (Kero 1-K) and n-paraffin solvent (Norpar 15), both obtained from Imperial Oil Ltd. To determine the optimum level of initial biomass concentration, n-paraffin concentration, iron concentration and temperature for the production of citric acid, a central composite design was developed using 200 ml batch flask fermentations. The design involved conducting 31 batch flask fermentations under various combinations of high and low values of these four parameters. These optimum levels of the above operating parameters were implemented in larger scale (7litre) fermentations. These fermentations were conducted in a 14L Chemap fermentor. The fermentations investigated the effects of aeration, agitation (mechanical agitation from the fermentor and an external agitator), and batch versus fed-batch systems on biomass and citric acid production. (Abstract shortened by UMI.)