초록
<P><B>Abstract</B></P> <P>Propionic acid (PA) is a specialty chemical; its calcium salt is widely used as food preservative. Soy molasses (SM), a low-value byproduct from soybean refinery, contains sucrose and raffinose-family oligosaccharides (RFO), which are difficult to digest for most animals and industrial microorganisms. The feasibility of using SM for PA production by <I>P. acidipropionici</I>, which has genes encoding enzymes necessary for RFO hydrolysis, was studied. With corn steep liquor as the nitrogen source, stable long-term PA production from SM was demonstrated in sequential batch fermentations, achieving PA productivity of >0.8 g/L h and yield of 0.42 g/g sugar at pH 6.5. Economic analysis showed that calcium propionate as the main component (63.5%) in the product could be produced at US $1.55/kg for a 3000-MT plant with a capital investment of US $10.82 million. At $3.0/kg for the product, the process offers attractive 40% return of investment and is promising for commercial application.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Soy molasses (SM) is a byproduct containing soy oligosaccharides difficult to digest. </LI> <LI> Propionic acid (PA) production from untreated SM by <I>P. acidipropionici</I> was studied. </LI> <LI> PA productivity >0.8 g/L h and yield of 0.42 g/g were obtained from SM. </LI> <LI> The process compares favorably with glucose or other biomass feedstocks in cost. </LI> <LI> This offers an economical process for production of food-grade calcium propionate. </LI> </UL> </P>