Genetic identification of bacterial strains.

Oxidative stress is a condition in which the body loses balance between the production of free radicals and the body’s ability to neutralize them. The role of antioxidants is to protect cells and tissues from the harmful effects of excessive amounts of free oxygen radicals. Lactic acid bacteria (LAB) can exhibit significant antioxidant properties which is the subject of research by many scientists. The aim of the work was isolation, phenotypic and genotypic identification, and evaluation of the antioxidant activity of twenty-one bacterial strains from raw fermented beef hams and the environment of a meat factory. The bacteria were screened in vitro by investigating their DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) free radical scavenging activity, superoxide anion tests, hydroxyl radical resistance, superoxide dismutase and catalase activity, and hydrogen peroxide resistance. As a result of the conducted research, 21 bacterial strains were isolated. They were assigned to Lactiplantibacillus plantarum (14), Lactiplantibacillus pentosus (3), Lactiplantibacillus argentoratensis (2), Lacticaseibacillus paracasei (1), and Pediococcus pentosaceus (1). The strains were compared with each other and some of them were able to scavenge free radicals DPPH (1.08–36.91%), ABTS (11.24–51.05%), and superoxide anions (3.04–96.70%). Furthermore, resistance to high concentrations of hydrogen peroxide (0.4–1.0 mM H2O2) and hydroxyl radicals (25.90–99.22%) has been demonstrated. Some strains produced superoxide dismutase, while none of them produced catalase. The findings indicated that some LAB strains could be promising starter candidates with antioxidant properties.

氧化应激（oxidative stress）是指机体在自由基产生与自身清除能力之间失去平衡的一种状态。抗氧化剂的作用在于保护细胞与组织免受过量氧自由基的有害损伤。乳酸菌（Lactic Acid Bacteria, LAB）可表现出显著的抗氧化特性，这亦是众多科研人员的研究热点。本研究的目的为：从生鲜发酵牛肉火腿及肉厂环境中分离21株细菌，并对其进行表型与基因型鉴定，同时评估其抗氧化活性。研究通过体外实验对这些细菌进行筛选，检测其DPPH（1,1-二苯基-2-三硝基苯肼，1,1-diphenyl-2-picrylhydrazyl）与ABTS（2,2'-联氮-双(3-乙基苯并噻唑啉-6-磺酸)，2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)）自由基清除活性、超氧阴离子检测、羟自由基抗性、超氧化物歧化酶与过氧化氢酶活性，以及过氧化氢抗性。经本次研究，共分离得到21株细菌，经鉴定分别归属为植物乳杆菌（Lactiplantibacillus plantarum，14株）、戊糖乳杆菌（Lactiplantibacillus pentosus，3株）、阿根廷乳杆菌（Lactiplantibacillus argentoratensis，2株）、副干酪乳杆菌（Lacticaseibacillus paracasei，1株）以及戊糖片球菌（Pediococcus pentosaceus，1株）。对各菌株进行两两比较后发现，部分菌株可清除DPPH自由基（清除率1.08%~36.91%）、ABTS自由基（11.24%~51.05%）以及超氧阴离子（3.04%~96.70%）。此外，部分菌株还表现出对高浓度过氧化氢（0.4~1.0 mM H₂O₂）与羟自由基（25.90%~99.22%）的抗性。部分菌株可产生超氧化物歧化酶，但未检测到过氧化氢酶的产生。本研究结果表明，部分乳酸菌菌株可作为具备抗氧化特性的潜在发酵剂候选菌株。