查看更多>>摘要：N-acetylglucosamine(GlcNAc)is an amino monosaccharide that has a variety of bioactivities and is widely used in pharmaceutical and food industries.Production of GlcNAc by chitin hydrolysis is limited by the supply of raw materials and encounters the risk of shellfish protein contamination.For efficient biosynthesis of GlcNAc,one challenge is to balance the carbon distribution between growth and production.Here,we applied the strategy of synergistic carbon utilization,in which glycerol supports cell growth and provides the acetyl group of GlcNAc while glucose serves as the precursor to glucosamine.The efficiency of GlcNAc production was stepwise improved by blocking the product re-uptake and degradation,strengthening the biosynthetic pathway and synergistically utilizing two carbon sources.With these efforts,the final strain produced 41.5 g/L GlcNAc with a yield of 0.49 g/g of total carbon sources.In addition,we also explored the feasibility of using acetate as a cheap carbon source to partly replace glycerol.This study provides a promising alternative strategy for sustainable and efficient pro-duction of GlcNAc.
查看更多>>摘要：Glucose isomerase(GI)is an enzyme with high potential applications.Characterization of GI producing bacteria with interesting properties from an industrial point of view is essential.Bacillus sp.,Paenarthrobacter sp.,Chrys-eobacterium sp.,Hymenobacter sp.,Mycobacterium sp.,and Stenotrophomonas sp.were isolated from soil samples.Optimization of enzyme production yield was investigated in various fermentation conditions using response surface methodology.All isolates exhibited maximum GI activity at 40 ℃,pH 6-8 after 4 days of incubation.A mixture of peptone/yeast extract or tryptone/peptone enhanced higher enzyme production.The same trend was observed in fermentation medium containing 1％xylose or 2％-2.5％wheat straw.This study advanced the knowledge of these bacterial isolates in promoting wheat straw as feedstock for the bio-based industry.
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