- 期刊
伽瑪輻射誘變少孢根黴菌合併乳桿菌共發酵大豆產物異黃酮成分分析
The Changes in Isoflavones of Soybean Tempeh Fermented with Lactobacillus and Gamma-irradiated Rhizopus oligosporus
摘要
天貝是富有營養價值的印尼傳統大豆發酵食品，其主要由根黴屬真菌發酵蒸煮豆類製成，常用菌種為少孢根黴菌（Rhizopus oligosporus），其擁有高活性蛋白酶與脂解酶，因此可將大豆大分子轉換為人體容易利用的營養成分，並可透過其β-葡萄糖苷酶水解人體不易吸收的各式寡醣與醣苷類物質。大豆異黃酮多為人體不易吸收的丙二醯基異黃酮配醣體或異黃酮配醣體，可被β-葡萄糖苷酶水解成人體易吸收的非醣體。少孢根黴菌可分泌抑菌物質抑制微生物生長，但不抑制植物乳桿菌，前人研究顯示兩菌可共同培養且生長良好。乳桿菌也會產生β-葡萄糖苷酶，與少孢根黴菌共同發酵可增加寡醣與醣苷類物質的水解，提升大豆發酵食品的生物利用率。故本研究首先將市售少孢根黴菌菌株以伽瑪輻射誘變後篩選具開發潛力之誘變菌株，將候選菌株再與乳桿菌共發酵富含異黃酮之十石金珠大豆製成天貝產品，並探討異黃酮成分生物轉化之效果。透過液態培養法篩選出具有蛋白酶、β-葡萄糖苷酶及高脂解酶活性之候選菌株，發現R. oligosporus 4k1、4k2及4k3誘變菌株具有高活性大分子分解能力。將各候選菌株搭配植物乳桿菌及鼠李糖乳桿菌固態發酵金珠大豆後，以高效能液相層析法儀分析異黃酮成分與含量，證實合併發酵具有增強去醣基異黃酮的潛力，以R. oligosporus 4k1或R. oligosporus 4k2誘變菌株搭配植物乳桿菌可產生高量去醣基異黃酮。本研究成果透過液態培養分析酵素活性篩選優質菌株，並以小量固態發酵證實少孢根黴菌合併植物乳桿菌共發酵可提升生物活性分子，極具植物性蛋白產品開發潛力。
並列摘要
The nutrition-rich tempeh is a traditional Indonesian food made by fermenting steamed soybean with microbes. Rhizopus oligosporus is the most prevalent fungal species isolated from commercial tempeh cakes. R. oligosporus produces highly active decomposing enzymes, such as protease and lipase to biotransform macromolecules into low-molecular-weight metabolites, and β-glucosidase to hydrolyze less bioavailable oligosaccharides and glycosides. Soy isoflavones are mostly malonyl-glucosides or glucosides, which need β-glucosidase to convert to the easily absorbed aglycones. R. oligosporus can secrete antibacterial substances to inhibit the growth of microorganisms but does not inhibit Lactobacillus. It is known that the two microbes grow well in co-cultivation. Like R. oligosporus, Lactobacillus also produces β-glucosidase, and the co-fermentation of tempeh can significantly improve the bioavailability of isoflavones in fermented soybean tempeh. In this study, the commercially available R. oligosporus and its derivative mutant strains irradiated by gamma-ray were used to co-ferment the isoflavone-rich Glycine max Shi-Shi with Lactobacillus bacteria, to explore the potential of developing novel soybean fermentation products. The study screened candidate strains with high protease, lipase, and β-glucosidase activity with a liquid culture method. It was found that R. oligosporus 4k1, 4k2, and 4k3 mutants have high activity to decompose large molecules. The candidate strains were then combined with L. plantarum and L. rhamnosus to solid-state ferment the Shi-Shi soybeans, and then high-performance liquid chromatography was used to analyze their isoflavone composition. The co-fermentation increases the amounts of isoflavone aglycones, especially in the groups fermented with R. oligosporus 4k1 or 4k2 mutants combined with L. plantarum. The current study screened out high-enzyme activity candidates generated by the remarkable gamma-ray irradiation mutagenesis and confirmed that the co-fermentation of R. oligosporus and L. plantarum increased biologically active compounds, showing the great potential to develop plant-based protein products.