Specific sterilization of psychrotrophs in foods by inactivation of alanine racemase

嗜冷菌在自然界中分布广泛，在低温下储存的食品往往会变质。因此，为了更好地了解食品的保鲜，人们对细菌进行了研究，尽管嗜冷菌很容易通过加热灭菌，但它们的胞外水解酶存活下来，降低了食品的质量。因此，对食品中的耐冷菌进行生长前的灭菌，对食品的低温保存具有重要意义。丙氨酸消旋酶(EC 5.1.1.1)是一种5‘-磷酸吡哆醛依赖的酶，催化L和D-丙氨酸的消旋。该酶广泛存在于细菌中，通过提供D-对映体，在细菌细胞壁肽聚糖的合成中是必不可少的。肽聚糖的生物合成是细菌所特有的，因此该酶一直是抗菌药物…的靶点。更多的GS。研究了嗜冷菌对有机酸和香料的敏感性，并与嗜中菌进行了比较，以期开发一种基于丙氨酸外消旋酶失活的高效杀菌方法。荧光假单胞菌和嗜冷菌等嗜冷菌对浓度为0.01%的柠檬酸盐、醋酸盐、乳酸和琥珀酸的敏感性高于嗜中菌。该浓度的有机酸对丙氨酸外消旋酶也有一定的灭活作用。嗜冷菌对不同香料的敏感性不同，但嗜冷菌对各种香料的敏感度较中温菌高。当等体积的多香料、姜黄、肉豆蔻和月桂叶提取物混合并分析时，混合提取物在0.016%的浓度下完全抑制所有被调查的嗜冷菌的生长6天。茄子、黄瓜和卷心菜用0.016%混合浸提液在25℃下浸泡10分钟，在4℃下贮藏11天，对耐冷菌的生长完全抑制。混合香料提取物可能对抑制嗜冷菌有用。较少

Psychrotrophic bacteria are widely distributed in nature, and often cause deterioration in foods stored at a low temperature. Accordingly, the bacteria have been studied to better understand food preservation, While psychrotrophs are easily sterilized by heat treatment, their extracellular hydrolytic enzymes survive and degrade the quality of foods. Therefore, sterilizing psychrotrophs before their growth in foods is important for food preservation at low temperature. However, there is no effective sterilization method of psychrotrophs in foods other than thermal sterilization, which often changes the original taste.Alanine racemase (EC 5.1.1.1) is a pyridoxal 5'-phosphate-dependent enzyme catalyzing racemization of L- and D-alanine. The enzyme occurs widely in bacteria and is essential in synthesis of peptidoglycan of bacterial cell walls by providing the D-enantiomer. The peptidoglycan biosynthesis is unique to bacteria, and therefore the enzyme has been a target of antibacterial dru … More gs. We examined the sensitivity of psychrotrophs to organic acids and spices in comparison with mesophiles, in order to develop an effective sterilization method of psychrotrophs based upon inactivation of alanine racemase.Fsychrotrophs such as P.fluorescens and B.psychrosaccharolyticus were found to be more sensitive to citrate, acetate, lactate, and succinate at 0.01% concentration than the mesophiles. The organic acid at the concentration also inactivated alanine racemase. Mesophiles were tolerant to the treatment and the intracellular alanine racemase in mesophiles was not inactivated.Also, psychrotrophs were more sensitive to various spices than the mesophiles, although the sensitivity of psychrotrophs to each spice was different depending on the species. When an equal volume of allspice, turmeric, nutmeg, and laurel leaves extracts was mixed and analyzed, the mixed extract completely suppressed the growth of all surveyed psychrotrophs at the concentration of 0.016% for 6 days. When eggplant, cucumber, and cabbage were soaked in the 0.016% mixed extract at 25oC for 10 min and stored at 4oC for 11 days, the growth of psychrotrophs was completely suppressed. The mixed spice extract may be useful for the suppression of psychrotrophs. Less