Increased production of S-adenosyl-L-methionine using recombinant <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> sake K6

S. cerevisiae sake K6 was the firstly isolated industrial strain to overproduce S-adenosyl-L-methionine (SAM). Although the strain has advantages over other strains, such as GRAS (generally recognized as safe) property, the S. cerevisiae K6 has not been further developed with DNA recombinant technology due to the lack of a proper genetic marker. In this study, UV mutagenesis was conducted with S. cerevisiae sake K6. With the method, a mutant of sake yeast with leucine auxotroph, K6-1, was isolated. The mutant showed comparable growth rate and SAM productivity with its wild type. Using the auxotroph as a genetic marker, a SAM synthase in S. cerevisiae, SAM2, was overexpressed in the mutant strain. This recombinant DNA technology successfully increased SAM productivity in sake yeast. This article is dedicated to Professor Chul Soo Lee in commemoration of his retirement from Department of Chemical and Biological Engineering of Korea University.     

表达人肝细胞生长因子突变体——NK4工程菌的发酵工艺研究

目的　建立重组NK4融合基因工程菌的发酵工艺。方法　采用锥形瓶、发酵罐发酵 ,对工程菌生长和表达条件如pH、诱导时间及诱导剂浓度等方面进行优化。确定其最佳诱导表达条件 ,在 15L自控发酵罐中进行分批补料培养。结果　在 15L发酵罐进行工程菌发酵 ,菌体收获量湿重可达 2 4 .6g L± 0 .98g L ,目的蛋白的表达量保持在菌体总蛋白的 5 0 %左右 ,发酵时间为 11h。结论　建立了周期短、产率高且稳定可靠的发酵工艺。     

Ethanol production from acorn starch by tannin tolerance mutant Pachysolen tannophilus

The acorn starch physicochemical properties were studied, and the acorn flour was used to ferment fuel ethanol by tannin tolerance mutants. The results showed that the gelatinization temperature of acorn starch lower than cassava starch and corn starch, which indicated that the gelatinization of acorn starch is easier than corn starch and cassava starch; Two tannin-tolerance mutant strains P05 and P18 were obtained after UV irradiation and tannin gradient domestication. Use of mutant P18 may decrease the extraction times of tannin from 5 to 3 times, which simplifies the production process and reduces the ethanol production cost.