干酪乳杆菌发酵液中的主要有机酸及其抑菌性

干酪乳杆菌在食品生物防腐方面起着重要的作用。为研究干酪乳杆菌发酵产生的有机酸的分离方法及其抑菌活性,采用乙酸乙酯萃取干酪乳杆菌的培养上清液,通过旋转蒸发仪对各萃取相进行浓缩,并采用spot-on-lawn改进法研究其抑菌活性,利用高效液相色谱(HPLC)分析萃取液中的主要有机酸成分。结果表明,乙酸乙酯相旋蒸余相对大肠杆菌O157:H7、金黄色葡萄球菌和单核细胞增生李斯特菌三种食源性致病菌均表现出很好的抑菌效果,且对大肠杆菌O157:H7和单核细胞增生李斯特菌的抑制最为明显,抑菌圈直径分别达到(20.00±0.82)、(21.67±0.94) mm,其主要的抑菌有机酸组分为乳酸、乙酸和苯乳酸。该研究为分离乳酸菌发酵液中有效活性抑菌物质提供了一种确实可行的方法。

Main Organic Acids and Antibacterial Activity of Lactobacillus casei Fermentation Broth

Lactobacillus casei (Lb. casei) plays an important role in food biological preservation. In order to study the separating method of organic acids and antibacterial activity of Lb. casei, the culture supernatant of Lb. casei was extracted by ethyl acetate. The extraction phases were concentrated by the rotary evaporator. The antibacterial activity was determined by modified spot-on-lawn method. The main organic acids of extraction were determined by high performance liquid chromatography (HPLC). The result showed that the ethyl acetate cyclosis appeared very good antibacterial activity against the three kinds of foodborne pathogens, Escherichia coli O157:H7, Staphylococcus aureus and Listeria monocytogenes. Inhibition of the growth of Escherichia coli O157:H7 and Listeria monocytogenes were most obvious, the diameters of inhibition zone were (20.00±0.82) mm and (21.67±0.94) mm, respectively. The main antibacterial organic acids were lactic acid, acetic acid and phenyl lactic acid analyzed by HPLC. The study provided a feasible method for isolating the antibacterial substances from the culture supernatant of lactic acid bacteria.