No abstract

Mannheimia succiniciproducens MBEL55E isolated from bovine rumen is able to produce a large amount of succinic acid in a medium containing glucose, peptone, and yeast extract. In order to reduce the cost of the medium, whey and corn steep liquor (CSL) were used as substrates for the production of succinic acid by M. succiniciproducens MBEL55E. Anaerobic batch cultures of M. succiniciproducens MBEL55E in a whey-based medium containing CSL resulted in the production of succinic acid with a yield of 71% and productivity of 1.18 g/l/h, which are similar to those obtained in a whey-based medium containing yeast extract (72% and 1.21 g/l/h). Anaerobic continuous culture of M. succiniciproducens MBEL55E in a whey-based medium containing CSL resulted in a succinic acid yield of 69% and a succinic acid productivity as high as 3.90 g/l/h. These results show that succinic acid can be produced efficiently and economically by M. succiniciproducens MBEL55E from whey and CSL.

SYNOPSISThe copolymerization of L,L-lactide and c-caprolactone was carried out using antimony trioxide and stannous octoate as catalysts. The effect of polymerization catalysts on the physical and the chemical microstructures of this copolymer was investigated by 13C NMR and DSC analysis. Antimony trioxide causes more random sequence distribution within the copolymer chain due to its higher transesterification characteristic than stannous octoate. The copolymer samples made with the antimony trioxide catalyst seem to have more amorphous phase structure, than those prepared using stannous octoate which are semicrystalline for the entire compositional range due to blocky copolymer sequences. 0 1994 John Wiley & Sons, Inc.

The basicities of benzamide and of 11 meta-and para-substituted benzamicles in sulphuric acid media have been determined by a spectrophotometric method. The pKnn+ values of the protonated benzamides were found to be proportional to the Hammett CT constants for the substituents, unlike the pRsn+ values of the protonated benzaldehydes, acetophenones, and benzoic acids, which are approxi~llately proportional to u+ constants. The lack of conjugation between the protonated amide group and the ring, which is indicated by these results, is most easily interpreted in terms of N-protonation although 0-protonation cannot be completely excluded. Irarious other aspects of the problem of N-versus 0-protonation are also discussed.

To develop a cost-effective fermentation medium, spent brewer's yeast hydrolysate was evaluated as a nitrogen source for succinic acid production by Actinobacillus succinogenes NJ113 in glucose-containing media. Autolysis and enzymatic hydrolysis were used to hydrolyze the spent brewer's yeast cells to release the nutrients. The results showed that enzymatic hydrolysis was a more effective method due to the higher succinic acid yield and cell growth. However, the incomplete glucose consumption indicated existence of nutrient limitation. Vitamins were subsequently identified as the main limiting factors for succinic acid production using enzymatically hydrolyzed spent brewer's yeast as a nitrogen source. After the addition of vitamins, cell growth and succinic acid concentration both improved. As a result, 15 g/L yeast extract could be successfully replaced with the enzymatic hydrolysate of spent brewer's yeast with vitamins supplementation, resulting in a production of 46.8 g/L succinic acid from 68 g/L glucose.