Bacteriocins as interventions for food safety

消费者对新鲜的、加工最少的、方便的食品的需求导致了冷藏即食食品的大量增加。目前，冷藏是唯一的障碍生长的食源性病原体可以污染这些产品。乳酸菌（LAB）产生抗菌肽，被称为细菌素，它可以抑制一些致病菌的生长。需要进一步发展检测这些化合物的灵敏分析技术。我们开发了一种使用基质辅助激光解吸/电离飞行时间质谱仪检测细菌素的灵敏方法，并将该方法用于确定食品中批准使用的细菌素nisin的命运。然而，我们还不能在食物中检测到其他细菌素的产生。需要进一步研究以提高检测食品中细菌素的分析技术的灵敏度和特异性。最近的研究表明，在一个模型系统中存在不止一种细菌素可以显著增加对食源性病原体的抑制活性。然而，在单一生物体中产生多种细菌素并没有导致抗菌活性的增加。如果我们要优化细菌素在LAB中的生产，就必须克服这个问题。本研究计划的目的是：1)优化食品中细菌素的检测方法；2)开发基于遗传学的策略来提高LAB中多种细菌素的生产。这项研究的成功成果将为食品工业提供最低限度加工肉类的有效生物防腐剂，并将为检测食品中的细菌素提供分析方法。进一步了解乳酸菌和细菌素在微生物生态学中的作用，将极大地促进它们的应用，从而提高我们食品供应的安全性。

Consumer demand for fresh, minimally processed, convenient food products has resulted in a tremendous increase in the availability of refrigerated, ready-to-eat foods. Currently, refrigeration is the only hurdle to the growth of foodborne pathogens that can contaminate these products. Lactic acid bacteria (LAB) produce antibacterial peptides, known as bacteriocins, which inhibit the growth of some pathogenic bacteria. There is need for further development of sensitive analytical techniques for detection of these compounds.  We developed a sensitive method for detection of bacteriocins using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer and this method was used to determine the fate of nisin, a bacteriocin that is approved for use in foods.  However, we have not been able to detect the production of other bacteriocins in foods.  Further research is required to improve the sensitivity and specificity of analytical techniques for detection of bacteriocins produced in foods.  Recent research has shown that the presence of more than one bacteriocin in a model system can dramatically increase the inhibitory activity against foodborne pathogens.  However, production of multiple bacteriocins in a single organism has not resulted in increased antimicrobial activity. This will have to be overcome if we are to optimize bacteriocin production in LAB.The objectives of this research program are to: 1) optimize methods for detection of bacteriocins in foods; and to 2) develop genetic-based strategies to improve production of multiple bacteriocins in LAB.  The successful outcome of this research will provide the food industry with effective biopreservatives for minimally processed meats and will provide assays for detection of bacteriocins in foods. Further understanding of the role of lactic acid bacteria and bacteriocins in microbial ecology will greatly enhance their application as hurdles to enhance the safety of our food supply.