ABSTRACT
Over the last 3 decades, there has been a resurgence of interest in large-scale production of fermentation chemicals due to the sharp increase in petroleum cost. So, the potential role of a new energy efficient fermentation technology is receiving growing attention. The current economic impact of fermentation chemicals, however, is still limited, in large part because of difficulties of product recovery. Thus, for fermentation products to penetrate the organic chemicals industry, substantial improvements in the existing recovery technology are needed. Organic acids are widely used in the food, pharmaceutical, and chemical industries. Fermentation technology for the production of organic acids in particular has been known for more than a century and acids have been produced in aqueous solutions. Propionic acid is used in the manufacture of herbicides, chemical intermediates, artificial fruit flavors, pharmaceuticals, cellulose acetate propionate, and preservatives for food, animal feed, and grain (Playne, 1985). Commercial production of propionic acid is chiefly carried out by chemical synthesis from petroleum feedstocks (Playne, 1985), but fermentation is an attractive alternative to produce this acid from renewable resources. Several carbon sources have been used for this fermentation such as glucose (Emde and Schink, 1990), xylose (Carrondo et al.,
1988), maltose (Babuchowski et al., 1993), sucrose (Quesada-Chanto et al., 1994) and whey lac tose (Lewis and Yang, 1992). The conventional method for the recovery of propionic acid from fermentation broth is the calcium hydroxide precipitation method. This method of recovery is expensive and unfriendly to the environment as it consumes lime and sulfuric acid and also produces a large quantity of calcium sulfate sludge as solid waste. Thus, there is a need to look at other methods of producing propionic acid.
