Wu Qinglong, Shah Nagendra P
Food and Nutritional Science, School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong.
Front Microbiol. 2018 Mar 13;9:445. doi: 10.3389/fmicb.2018.00445. eCollection 2018.
Exo-polysaccharide (EPS) produced by dairy starters plays critical roles in improving texture and functionalities of fermented dairy products. One of such high EPS producers, ASCC 1275 (ST1275) was used as a model dairy strain to understand the stimulation of its EPS production under optimal milk fermentation conditions. The mRNA-seq analysis and targeted pathway analysis indicate that genes associated with lactose (milk sugar) catabolism, EPS assembly, proteolytic activity, and arginine/methionine/cysteine synthesis and transport in ST1275 were significantly up-regulated under the optimized conditions of pH 5.5, 40°C, or WPI supplementation compared to that of pH 6.5 and 37°C, respectively. This indicates that genes involved in above metabolisms cooperate together for improving EPS yield from ST1275. This study provides a global view map on potential targeted pathways and specific genes accounted for enhanced EPS production in and that could be modulated by fermentation conditions.
乳制品发酵剂产生的胞外多糖（EPS）在改善发酵乳制品的质地和功能方面起着关键作用。其中一种高产EPS的菌株ASCC 1275（ST1275）被用作典型的乳制品菌株，以了解在最佳牛奶发酵条件下其EPS产生的刺激因素。mRNA测序分析和靶向途径分析表明，与pH 6.5和37°C相比，在pH 5.5、40°C或添加乳清蛋白分离物（WPI）的优化条件下，ST1275中与乳糖（牛奶糖）分解代谢、EPS组装、蛋白水解活性以及精氨酸/蛋氨酸/半胱氨酸合成和转运相关的基因显著上调。这表明参与上述代谢的基因共同协作，以提高ST1275的EPS产量。本研究提供了一个关于潜在靶向途径和特定基因的全局视图图谱，这些基因导致了ST1275中EPS产量的提高，并且可以通过发酵条件进行调节。
