Rahman Md Moklesur, Sazili Awis Qurni, Ahmad Siti Aqlima, Khalil Khalilah Abdul, Ismail-Fitry Mohammad Rashedi, Sarker Md Sazedul Karim
Halal Product Research Institute, Universiti Putra Malaysia, UPM Serdang, 43400, Malaysia.
Bangladesh Livestock Research Institute (BLRI), Savar, Dhaka, Bangladesh.
BMC Microbiol. 2025 Aug 6;25(1):485. doi: 10.1186/s12866-025-04123-z.
Antimicrobial resistance (AMR) poses a significant threat to human health and food safety. Lactic acid bacteria (LAB) produce bioactive compounds, known as postbiotics, that act as promising natural preservatives with broad-spectrum antimicrobial activity. This study aimed to evaluate the antimicrobial spectrum, production dynamics, and physicochemical properties of postbiotics derived from five LAB strains: Lactobacillus plantarum NBRC 3070, Lactobacillus acidophilus ATCC 4356, Lactobacillus casei ATCC 393, Lactobacillus rhamnosus GG ATCC 53103, and Bifidobacterium animalis subsp. lactis ATCC 27673. The antimicrobial activity of these postbiotics was assessed against several Gram-positive and Gram-negative pathogens. A crude bacteriocin-like inhibitory substance (BLIS), a postbiotic component, was partially purified using ammonium sulfate purification and characterized enzymatically. Its molecular weight was estimated by SDS-PAGE. The results showed that postbiotics, particularly those from L. plantarum and L. acidophilus, exhibited strong antimicrobial activity. The inhibitory effect was most pronounced against Escherichia coli, Salmonella Typhimurium, and Staphylococcus aureus after a 16-h exposure. The postbiotics production peaked between 24 and 36 h of incubation, achieving 85.71-89.28% inhibition. These postbiotics remained stable at high temperatures (up to 121 °C), across a wide pH range (3-5 and 9-11), and under varying salt concentrations. Neutralized cell-free supernatants from L. plantarum, L. acidophilus, L. casei, and L. rhamnosus GG retained antimicrobial activity, and enzyme treatments confirmed the proteinaceous nature of the BLIS. SDS-PAGE revealed diffuse protein bands between < 3.3 and 6.5 kDa. Lyophilization enhanced the concentration and stability of antibacterial compounds by reducing water content. In addition to BLIS, LAB strains produced other antimicrobial metabolites, including lactic acid, acetic acid, hydrogen peroxide, fatty acids, and notably, oleic acid. These postbiotic components remained effective after one month of storage at 4 °C and 20 °C for one month. The novelty of this study lies in its comprehensive characterization of postbiotics from well-established LAB strains across multiple functional parameters. Overall, the findings suggest that these LAB-derived postbiotics are stable, effective, and hold potential as natural antimicrobial agents in food preservation.
抗菌耐药性（AMR）对人类健康和食品安全构成重大威胁。乳酸菌（LAB）产生被称为后生元的生物活性化合物，这些化合物作为有前景的天然防腐剂，具有广谱抗菌活性。本研究旨在评估源自五株乳酸菌的后生元的抗菌谱、产生动态和理化性质，这五株乳酸菌分别是植物乳杆菌NBRC 3070、嗜酸乳杆菌ATCC 4356、干酪乳杆菌ATCC 393、鼠李糖乳杆菌GG ATCC 53103和动物双歧杆菌亚种乳酸亚种ATCC 27673。评估了这些后生元对几种革兰氏阳性和革兰氏阴性病原体的抗菌活性。一种粗制的类细菌素抑制物质（BLIS），作为后生元的一个组成部分，通过硫酸铵纯化进行了部分纯化，并进行了酶学表征。通过SDS-PAGE估计其分子量。结果表明，后生元，特别是来自植物乳杆菌和嗜酸乳杆菌的后生元，表现出很强的抗菌活性。在暴露16小时后，对大肠杆菌、鼠伤寒沙门氏菌和金黄色葡萄球菌的抑制作用最为明显。后生元的产生在培养24至36小时达到峰值，抑制率达到85.71-89.28%。这些后生元在高温（高达121°C）、宽pH范围（3-5和9-11）以及不同盐浓度下都保持稳定。植物乳杆菌、嗜酸乳杆菌、干酪乳杆菌和鼠李糖乳杆菌GG的中和无细胞上清液保留了抗菌活性，酶处理证实了BLIS的蛋白质性质。SDS-PAGE显示在<3.3至6.5 kDa之间有弥散的蛋白条带。冻干通过降低含水量提高了抗菌化合物的浓度和稳定性。除了BLIS，乳酸菌菌株还产生其他抗菌代谢产物，包括乳酸、乙酸、过氧化氢、脂肪酸，特别是油酸。这些后生元成分在4°C储存一个月和20°C储存一个月后仍然有效。本研究的新颖之处在于对来自成熟乳酸菌菌株的后生元进行了跨多个功能参数的全面表征。总体而言，研究结果表明这些源自乳酸菌的后生元稳定、有效，在食品保鲜中作为天然抗菌剂具有潜力。
