99A-14 |
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T. WANG and G. U. Yuksel. Dept. of Food Science & Toxicology, Univ. of Idaho, Agricultural Biotechnology Lab., Moscow, ID 83844-2312 Lactic acid is an intermediate-volume specialty chemical with widespread use in the pharmaceutical, chemical, and food industries. An approach that could significantly reduce the cost of lactic acid fermentation would be to employ microorganisms with the ability to convert starch directly to lactic acid and utilize low-cost or no-cost agricultural and industrial waste as substrate. Our long-range goal is to convert off-grade and small potatoes as well as potato processing waste to lactic acid by an efficient, rapid, and economical single step fermentation using amylolytic LAB as biocatalysts. The objective of this study was to identify promising LAB strains. The ability to hydrolyze starch was examined using Lactobacillus MRS medium containing starch. Extracellular alpha-amylase activity was determined using Ceralpha Assay Kit. The carbohydrate fermentation profiling was accomplished using API strips. A D-lactic acid/L-lactic acid kit was utilized to quantify lactic acid isomers. Fresh potatoes were used to design a Potato Broth Medium (PBM). Fermentation performance of LAB strains was evaluated in PBM. The concentrations of L-lactic acid, glucose, and starch were determined using an YSI 2700 Biochemistry Analyzer. Seventy-nine LAB strains were screened for the ability to hydrolyze starch. Seventeen strains, with varying extracellular alpha-amylase activity, hydrolyzed starch concentrations of 1-3%. The carbohydrate fermentation profiling indicated that all 17 strains could ferment glucose, galactose, fructose, and mannose, but only four strains could ferment L-arabinose and ribose. All 17 strains could successfully grow in PBM and make DL-lactic acid with varying L-lactic acid/D-lactic acid ratios. We have identified several amylolytic LAB strains that can be used to convert off-grade and small potatoes as well as potato processing waste to lactic acid, extending economical benefits to the relevant producer and industrial groups. Our current research deals with the optimization of fermentation parameters (media, temperature, pH, and time) for potential commercial applications.
Session 99A, Biotechnology: General
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