|Budget Amount *help
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2003: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2002: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2001: ¥2,200,000 (Direct Cost: ¥2,200,000)
Lactic acid is mainly used in the traditional food industry as an additive, and has recently drawn attention as the raw material for the production of biodegradable polylactic acid. With an increase in demand for environmentally friendly materials, lactic acid production by fermentation methods has gained interest. The economics of the process, however, depend on the development of an effective recovery method for lactic acid from the broth, because the separation and purification steps account for up to 50% of the production costs. Solvent extraction has been proposed as a promising recovery technique as an alternative to the conventional precipitation process. Recently, in situ extractive fermentation processes, in which lactic acid is simultaneously recovered by solvent extraction during the production of lactic acid in the fermentation broth, have been deemed attractive from the perspectives of suppression of the end-product (lactic acid) inhibition and enhanced reactor efficiency. In the present study, in order to repress the toxicity of the extractant and organic solvent we developed the new process for in situ extractive fermentation by using Lactobacillus fruclivorans NRIC0224 (hiochibacterium), which was alcoholophilic and could grow in the presence of 1-deanol. Tri-n-octylamine (TOA) in decanol gave the highest extractability of lactic acid. It was found that yeast extract and peptone in fermentation broth inhibited to extract lactic acid. The toxicity of TOA to Lb.fructivorans NRIC0224 was tested. In the presence of TOA and calcium carbonate (CaCO_3), the bacterium could grow, consume glucose, and produce lactic acid.
Based on these results, we examined the applicability of a column packed with alginate capsules containing the cells and calcium carbonate to the extractive fermentation of lactic acid. The extractive fermentation of lactic acid was successful from the points of view of cell growth and reduction of the end-product inhibition.