This study utilized a circular economy approach to convert unripe rice, a low-cost by-product of the rice milling industry, into biofuels using a biorefinery process. The recombinant yeast Saccharomyces cerevisiae ER T12.7 strain was tested for its ability to produce ethanol from unripe rice. In hydrolysis trials with 20 % (dw/v) unripe rice, ER T12.7 showed superior saccharification yields comparable to the commercial enzyme, STARGENTM 002. In 1-L bioreactor tests, ER T12.7 produced ethanol as efficiently as the parental ER V1 strain under simultaneous saccharification and fermentation conditions. The spent fermentation broth from both amylolytic strains was evaluated for biomethane production, achieving high yields of up to 373.61 mL CH4/g volatile solids. This research is the first to demonstrate process integration to produce ethanol and methane from rice waste sequentially, highlighting the potential of unripe rice in biorefining for a circular economy.

中文翻译：

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使用优质解淀粉重组酵母从稻米废料中集成生产生物乙醇和生物甲烷


本研究利用循环经济方法，通过生物精炼工艺将未成熟的大米（碾米行业的低成本副产品）转化为生物燃料。重组酵母酿酒酵母 ER T12.7 菌株测试了其从未成熟大米中生产乙醇的能力。在对 20% （dw/v） 未成熟大米的水解试验中，ER T12.7 显示出与商业酶 STARGENTM 002 相当的优异糖化产量。在 1 L 生物反应器测试中，在同时糖化和发酵条件下，ER T12.7 生产乙醇的效率与亲本 ER V1 菌株一样高效。对来自两种解淀粉菌株的废发酵液进行生物甲烷生产评估，实现了高达 373.61 mL CH4/g 挥发性固体的高产量。这项研究首次展示了从大米废料中依次生产乙醇和甲烷的工艺集成，突出了未成熟大米在生物精炼中实现循环经济的潜力。