Background
The intracellular molecule trehalose in Saccharomyces cerevisiae may have a major protective function under extreme environmental conditions. NTH1 is one gene which expresses trehalase to degrade trehalose. Small heat shock protein 12 (HSP12 expressed) plays a role in protecting membranes and enhancing freezing stress tolerance.
Results
An optimized S. cerevisiae CRISPR-Cpf1 genome-editing system was constructed. Multiplex genome editing using a single crRNA array was shown to be functional. NTH1 or/and HSP12 knockout in S. cerevisiae enhanced the freezing stress tolerance and improved the leavening ability after freezing and thawing.
Conclusions
Deleting NTH1 in the combination with deleting HSP12 would strengthen the freezing tolerance and protect the cell viability from high rates of death in longer-term freezing. It provides valuable insights for breeding novel S. cerevisiae strains for the baking industry through a more precise, speedy, and economic genome-editing system.
Soybean is an excellent source of plant-derived protein, and soy products are one of the important protein sources for vegetarians in Taiwan. Soybean production in Taiwan is not self-sufficient. Taiwan imports 2.5 million tons of soybeans annually. More than 90% of the imported soybeans are genetically modified. To provide an objective assessment on safety of genetically modified soybean and for post-market monitoring, we conducted a comparative assessment on key component compositions between imported genetically modified and organic soybeans. All the soybean samples were purchased from the local market to simulate the status of Taiwanese consumers purchasing soybeans. The genetically modified soybean samples were herbicide-tolerant soybeans. The contents of the proximate, the amino acid composition, the fatty acid composition, vitamins, minerals, isoflavones, and anti-nutritional factors of soybean samples were analyzed. Most contents of the key components of the genetically modified soybean had no significant difference with those of the organic soybean in this study. However, the contents of cysteine and α-linoleic acid were significantly lower in the genetically modified soybean samples, and the contents of crude fat, palmitic acid, stearic acid, oleic acid, linoleic acid, vitamin K1, and calcium were significantly higher in the genetically modified soybean samples. But they were all within the range of reference values. A total of 314 pesticide residues in each of the samples were analyzed. Only glyphosate residue was detected in the genetically modified soybean samples, but it is well below the threshold prescribed by the government. In summary, the imported genetically modified and organic soybeans purchased from Taiwan market were shown to be substantially equivalent in composition.
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