| Research Abstract |
For the purpose of degradation of cholesterol in foods materials, we have tried to bread lactic acid bacteria having a new function to degrade cholesterol. For three years, we have devoted the following research work and obtained fruitful results.
1. Many strains of lactic acid bacteria from traditional fermented foods in Japan, Indonesia, Philippines, Thailand, Nepal, Vietnam, Mongolia, and Egypt were isolated.
2. A strain of Lactobacillus plantarum isolated from a fermented fishery product, "Burong Bangus" in Philippines was selected and analyzed plasmids. By using the fragment of plasmids from L.plantarum, two useful vectors replicated in lactic acid bacteria and Escherichia coli were constructed.
3. By using the vector constructed, we obtained the best conditions of transformation of L.plantarum strain and established host-vector system in lactic acid bacteria.
4. The cholesterol oxidase gene (choA) was recombined with the vector and the strain of L.plantarum was transformed to choA^+.
5. The genes encoded cholesterol degradating enzymes were cloned and analyzed. The genes encoded ketosteroid-DELTA^I-dehydrogenase, ketosteroid-DELTA^5-isomerase and the regulator were found.
6. These cholesterol degradation enzymes are planning to express in lactic acid bacteria. The cholesterol containing food materials will be treated by these engineered lactic acid bacteria.
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