Federal regulations dictate that cheese producers cannot use the kinds of additives found in foods like deli meats to counteract this danger. One thing they can use, however, is bacterial cultures.<\/p>\n In the cheese production process, cheese makers use starter bacterial cultures to turn milk into cheese. In a recent study published in LWT,<\/a> D\u2019Amico found other bacterial cultures, known as protective cultures, can fight pathogens and prevent them from causing illness by hampering their ability to infect someone at several key points.<\/p>\n In previous studies, D\u2019Amico screened protective cultures to determine which could potentially be effective against common pathogens like Listeria<\/em>, E. coli<\/em>, or Salmonella<\/em>. His lab also screened to tell if these protective cultures would interfere with the starter cultures.<\/p>\n This research is among the first peer-reviewed studies to provide cheese producers with definitive evidence about how these cultures work.<\/p>\n Through this work, D\u2019Amico identified three commercially available protective cultures with the highest chance of being effective against Listeria monocytogenes<\/em>, the foodborne pathogen responsible for listeriosis.<\/p>\n Listeriosis can have life-threatening effects for those in high-risk groups, such as immunocompromised individuals and pregnant women. The pathogen has a 20-30% mortality rate, making it a significant public health concern.<\/p>\n Choosing from commercially available strains was an important consideration as, otherwise, cheese makers would have a difficult, if not impossible, time adopting D\u2019Amico\u2019s findings into their process.<\/p>\n D\u2019Amico used one culture of Lactococcus lactis<\/em> (LLN), and two different cultures of Lactiplantibacillus plantarum <\/em>(LP and LPP).<\/p>\n D\u2019Amico conducted a previous study showing that using a high concentration of protective cultures can effectively kill pathogens. In this study, D\u2019Amico used significantly higher concentrations of the pathogens than a person would normally consume to allow the pathogen to survive long enough to study the infection process.<\/p>\n Bacteria change the way they behave when they\u2019re in the presence of other, similar bacteria and can produce antimicrobial metabolites. When a pathogenic bacterium detects the presence of these cultures and their metabolites it enters a kind of \u201cfight or flight\u201d mode. The pathogen turns its focus to expressing genes important to surviving the competitor and turns off many of the nonessential functions that allow it to cause illness.<\/p>\n \u201cEvolutionarily, those are their competitors,\u201d D\u2019Amico says. \u201cTypically [a protective culture\u2019s] effect is limited to a certain group of pathogens.\u201d<\/p>\n In order to get sick from eating something contaminated with Listeria<\/em>, the pathogen needs to survive the inhospitable environment of the gastrointestinal tract. Then, it needs to attach to colon cells. Finally, it needs to enter those cells and cross the epithelial cell lining. Disrupting any of these steps will help prevent illness even if the pathogen doesn\u2019t die.<\/p>\n D\u2019Amico found protective cultures were effective at stopping Listeria <\/em>at key points in the infection process. Both of the Lactiplantibacillus plantarum<\/em> cultures disrupted Listeria\u2019s <\/em>ability to survive the gastrointestinal tract.<\/p>\n There was not a significant impact on the pathogen\u2019s ability to adhere to cells. However, LLN and LPP significantly reduced the pathogen\u2019s ability to invade colon cells and all three cultures disrupted transepithelial translocation, where the pathogen crosses the epithelial barrier by moving between the cells.<\/p>\n![\"\"](\"https:\/\/today.uconn.edu\/wp-content\/uploads\/2021\/12\/DAmico_210901a013-300x199.jpg\")