Data_Sheet_1_Function-Driven Design of Lactic Acid Bacteria Co-cultures to Produce New Fermented Food Associating Milk and Lupin.docx

Designing bacterial co-cultures adapted to ferment mixes of vegetal and animal resources for food diversification and sustainability is becoming a challenge. Among bacteria used in food fermentation, lactic acid bacteria (LAB) are good candidates, as they are used as starter or adjunct in numerous fermented foods, where they allow preservation, enhanced digestibility, and improved flavor. We developed here a strategy to design LAB co-cultures able to ferment a new food made of bovine milk and lupin flour, consisting in: (i) in silico preselection of LAB species for targeted carbohydrate degradation; (ii) in vitro screening of 97 strains of the selected species for their ability to ferment carbohydrates and hydrolyze proteins from milk and lupin and clustering strains that displayed similar phenotypes; and (iii) assembling strains randomly sampled from clusters that showed complementary phenotypes. The designed co-cultures successfully expressed the targeted traits i.e., hydrolyzed proteins and degraded raffinose family oligosaccharides of lupin and lactose of milk in a large range of concentrations. They also reduced an off-flavor-generating volatile, hexanal, and produced various desirable flavor compounds. Most of the strains in co-cultures achieved higher cell counts than in monoculture, suggesting positive interactions. This work opens new avenues for the development of innovative fermented food products based on functionally complementary strains in the world-wide context of diet diversification.

为实现食品多样化与可持续发展目标，设计适配植物源与动物源混合基质发酵的细菌共培养体系，正逐渐成为一项研究挑战。在食品发酵领域常用的细菌中，乳酸菌（lactic acid bacteria, LAB）是理想候选菌株，因其已作为发酵剂或辅助发酵剂广泛应用于各类发酵食品中，可实现食品保鲜、提升消化率并改善风味品质。本研究开发了一套乳酸菌共培养体系的设计策略，用于构建以牛乳与羽扇豆粉为原料的新型发酵食品，具体流程如下：（i）通过计算机模拟（in silico）预筛选具备靶向碳水化合物降解能力的乳酸菌物种；（ii）针对筛选获得的物种，开展97株菌株的体外（in vitro）筛选实验，检测其发酵碳水化合物、水解牛乳与羽扇豆中蛋白质的能力，并对表型相似的菌株进行聚类分析；（iii）从表型互补的聚类群中随机选取菌株进行组合，构建共培养体系。所设计的共培养体系成功实现了预设功能：可在较宽浓度范围内水解蛋白质，并降解羽扇豆中的棉子糖家族寡糖以及牛乳中的乳糖。此外，该体系还可降低产生不良风味的挥发性物质己醛，并生成多种优质风味化合物。共培养体系中的多数菌株相较于纯培养时具有更高的细胞数，提示菌株间存在正向相互作用。本研究为在全球饮食多样化的背景下，开发基于功能互补菌株的创新发酵食品开辟了全新路径。