高产γ-氨基丁酸短乳杆菌D17的水解燕麦乳发酵特性及安全性评估

Fermentation characteristics and safety evaluation of high-yield gamma-aminobutyric acid-producing Lactobacillus brevis D17 on hydrolyzed oat milk

【背景】短乳杆菌(Lactobacillus brevis)D17作为一株传统发酵食品来源的高产γ-氨基丁酸(gamma-aminobutyric acid,GABA)菌株,评估其发酵特性和安全性具有重要意义。【目的】研究短乳杆菌D17的发酵特性和安全性,为进一步开展益生功能研究奠定基础。【方法】基于MRS培养基和燕麦乳发酵试验评估菌株的发酵特性;通过将D17全基因组序列与毒力因子数据库(virulence factor database,VFDB)和耐药基因数据库(comprehensive antibiotic resistance database,CARD)进行比对,分析评估该菌株毒力因子和抗生素抗性基因的存在情况;抗生素药敏试验评估菌株的抗生素敏感性;小鼠毒理试验评估菌株的体内安全性。【结果】短乳杆菌D17能很好地发酵燕麦乳,乳酸产量能达到MRS培养基的82.5%,并且能利用燕麦乳中的内源谷氨酸产生480 mg/L GABA,能明显改善燕麦乳的风味特征;短乳杆菌D17无致病的毒力因子和抗生素抗性基因,虽然存在一些固有的抗生素抗性,但无可转移的抗生素耐药性风险;短乳杆菌D17能定殖于小鼠肠道,对小鼠不但无致病性,而且还对小鼠血清指标、肠道菌群具有一定的改善作用。【结论】短乳杆菌D17具有良好的植物基基质发酵潜能且为安全菌株,体现了其良好的益生潜能。

[Background]It is of great significance to evaluate the fermentation characteristics and safety of Lactobacillus brevis D17,a high gamma-aminobutyric acid(GABA)-producing bacterium from fermented grains for the production of Chinese liquor.[Objective]To investigate the fermentation characteristics and evaluate the safety of L.brevis D17,laying a foundation for further assessment of probiotic properties.[Methods]The MRS medium and hydrolyzed oat milk were used to study the fermentation characteristics of strain D17.The whole genome sequence of D17 was compared with the virulence factor database(VFDB)and the comprehensive antibiotic resistance database(CARD)to assess the presence of virulence genes and antibiotic resistance genes.The antibiotic susceptibility profile of L.brevis D17 was established by antibiotic susceptibility tests.The toxicological test in mice was carried out to assess the in vivo safety of L.brevis D17.[Results]L.brevis D17 showcased good fermentation performance on oat milk,with the lactate production reaching 82.5%of that in the MRS medium.Moreover,it produced 480 mg/L GABA from the glutamate in oat milk.Additionally,L.brevis D17 improved the flavor profile of oat milk.L.brevis D17 did not carry virulence genes or antibiotic resistance genes.Despite inherent antibiotic resistance,D17 strain had no risk of resistance transfer.L.brevis D17 colonized the mouse intestine without causing any disease or death.Moreover,it exerted positive effects on serum indicators and gut microbiota in mice.[Conclusion]L.brevis D17 showcased strong potential for fermentation of plant-derived substrates and was confirmed to be safe,demonstrating significant probiotic properties.