高产L-组氨酸功能性乳酸菌的筛选、鉴定及益生特性

Screening, Identification, and Probiotic Characterization of High L-Histidine-producing Functional Lactic Acid Bacteria

摘要:

【目的】从发酵食品中筛选具有高产L-组氨酸的功能性乳酸菌菌株，并对其益生特性进行评估。【方法】通过测定乳酸菌的生长曲线和产酸特性、最适生长温度与pH、抗逆特性、抗生素敏感性以及对病原菌的抑制能力，评估其益生特性。【结果】筛选出了一株发酵乳杆菌NC42，其L-组氨酸产量为939.77 mg/L。该菌株在0~6 h为生长迟缓期，6~18 h进入对数生长期，18 h后进入生长稳定期，其最适生长温度和pH分别为37 ℃和6.0。抗逆特性研究结果表明，该菌株在NaCl质量分数为4%以上的高渗透压下无法生存，能够耐受pH为2.5和3.0的强酸环境，在胆盐质量分数为0.10%时保持良好的活菌数，且在-20 ℃下贮存5 d能维持有益生作用的活菌数。表面特性测定结果表明，该菌株的表面疏水率为43.27%，属于中度疏水菌株，其自凝集率达52.13%。此外，该菌对不同抗生素的敏感性具有显著差异，其对青霉素、红霉素和头孢唑林等抗生素敏感。该菌株的发酵上清液对多种病原指示菌具有显著的抑制作用，其中对单增李斯特菌的抑制作用最明显，抑菌圈直径为17.10 mm。【结论】该高产菌株具有一定的益生特性与抗逆能力，为功能性益生菌菌种开发提供了理论基础。

Abstract:

[Objective] This study aimed to screen functional lactic acid bacterial strains with high L-histidine production from fermented foods and evaluate their probiotic characteristics. [Method] The probiotic characteristics of the isolates were assessed by determining their growth curves, acid-producing profiles, optimal growth temperature and pH, stress resistance characterization, antibiotic susceptibility, and inhibitory activity against pathogens.[Result]Limosilactobacillus fermentum NC42 with a L-histidine yield of 939.77 mg/L was successfully screened out. This strain had a lag growth phase from 0 h to 6 h, a logarithmic growth phase from 6 h to 18 h, and a stable growth phase after 18 h. The optimal growth temperature and pH were 37 ℃ and 6.0, respectively. The results of the stress resistance characterization showed that this strain could not survive when the NaCl mass fraction was above 4%, and it could tolerate strong acidic environments with pH 2.5 and 3.0 and maintain a good viable count at a bile salt mass fraction of 0.10%. This strain could maintain a viable count sufficient for probiotic effects for 5 d at -20 ℃. The results of surface property determination showed that its hydrophobicity was determined to be 43.27%, which indicated moderate hydrophobicity. The self-agglomeration rate of this strain was 52.13%. The strain showed significant differences in sensitivity to different antibiotics, with sensitivity to penicillin, erythromycin, and cefazolin. The fermentation supernatant of this strain had significant inhibitory effects on various indicator pathogens, with the most obvious inhibitory effect on Listeria monocytogenes, as evidenced by the inhibition zone diameter of 17.10 mm. [Conclusion] The screened strain had certain probiotic characteristics and stress resistance, which provides a basis for the functional probiotic development.