Dong YiNing, Ronholm Jennifer, Fliss Ismail, Karboune Salwa
Department of Food Science and Agricultural Chemistry, Macdonald Campus, McGill University, Montreal, QC, Canada.
Department of Food Science, Faculty of Agriculture and Food Sciences, Laval University, Quebec City, QC, Canada.
Probiotics Antimicrob Proteins. 2024 May 11. doi: 10.1007/s12602-024-10270-y.
Twenty-eight strains of lactic acid bacteria (LAB) were characterized for the ability to express enzymes of interest (including protease, xylanase, α-amylase, laccase, and glucose oxidase) as well as the ability to produce exopolysaccharide (EPS). The screening of enzyme capability for all LAB strains proceeded in a progressive 3-stage manner that helps to profile the efficiency of LAB strains in expressing chosen enzymes (Stage 1), highlights the strains with affinity for flour as the substrate (Stage 2), and discerns strains that can adapt well in a simulated starter environment (Stage 3). The theoretical ability of LAB to express these enzymes was also assessed using Basic Local Alignment Search Tool (BLAST) analysis to identify the underlying genes in the whole genome sequence. By consolidating both experimental data and information obtained from BLAST, three LAB strains were deemed optimal in expressing enzymes, namely, Lb. delbrueckii subsp. bulgaricus (RBL 52), Lb. rhamnosus (RBL 102), and Lb. plantarum (ATCC 10241). Meanwhile, EPS-producing capabilities were observed for 10 out of 28 LAB strains, among which, Lactococcus lactis subsp. diacetylactis (RBL 37) had the highest total EPS yield (274.15 mg polysaccharide/L culture) and produced 46.2% polysaccharide with a molecular mass of more than 100 kDa.
对28株乳酸菌（LAB）进行了特性分析，以确定它们表达目标酶（包括蛋白酶、木聚糖酶、α-淀粉酶、漆酶和葡萄糖氧化酶）的能力以及产生胞外多糖（EPS）的能力。对所有LAB菌株的酶活性筛选分三个阶段逐步进行，这有助于描绘LAB菌株表达所选酶的效率（第1阶段），突出对面粉作为底物具有亲和力的菌株（第2阶段），并识别能够在模拟发酵剂环境中良好适应的菌株（第3阶段）。还使用基本局部比对搜索工具（BLAST）分析评估了LAB表达这些酶的理论能力，以识别全基因组序列中的潜在基因。通过整合实验数据和从BLAST获得的信息，确定了三株在表达酶方面表现最佳的LAB菌株，即德氏乳杆菌保加利亚亚种（RBL 52）、鼠李糖乳杆菌（RBL 102）和植物乳杆菌（ATCC 10241）。同时，在28株LAB菌株中有10株观察到了产生EPS的能力，其中，乳酸乳球菌双乙酰亚种（RBL 37）的总EPS产量最高（274.15 mg多糖/升培养物），并产生了46.2%分子量超过100 kDa的多糖。
