具有良好半乳糖基转移酶活性的乳糖酶是工业制备低聚半乳糖(galacto-oligosaccharides, GOS)的主要酶制剂。通过筛选获得了以GOS为唯一碳源生长良好,在乳糖-葡萄糖-半乳糖中生长不良的长双歧杆菌B1172,确立了其GOS-生物量相关关系,进一步基于GOS-生物量相关关系建立起乳糖酶转苷活性的高通量筛选方法。运用此方法,从菌种库中筛选获得了5株具有较高转苷活性的乳糖酶产生菌株,可为后续此酶的克隆与分子进化奠定基础。
The lactase with the high galactosyl transferase activity is desired for the galacto-oligosaccharides (GOS) preparation. Bifidobacterium longum B1172 growing well on GOS but not on lactose-glucose-galactose was selected and its GOS-biomass correlation was established. A high-throughput screening method for transgalactosylation activity was subsequently developed and successfully applied for screening transgalactosylase-producing strains from the culture collection. Five strains producing lactase with the remarkably transgalactosyl activity were selected, which lay a foundation for further cloning and molecular evolution of the enzyme.
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