Discovering the Might of Salivaricin in Chicken Guts

Ever heard of tiny powerhouses living inside chicken guts? Meet Ligilactobacillus salivarius—a bacteria with a trick up its sleeve. Inside these microscopic beings lies a repA-type megaplasmid, housing a gene for salivaricin P (salP), a class IIb bacteriocin. Scientists decided to dig deeper into these little warriors, especially the ones capable of producing salivaricin P. They found 25 strains in broiler chickens and laying hens, splitting them into two groups: Type A (active bacteriocins) and Type B (no active bacteriocins). Zooming in, scientists noticed that salP bacteriocins were like tiny, positively charged bullets that could punch through certain bacteria like Listeria monocytogenes and Enterococcus faecalis. Their molecular weight? Around 4. 097 kDa and 4. 285 kDa for two types. And they all had a special code: the GXXXG motif.So why were Type B strains unable to produce active salivaricin? The culprits were missing lanT and hlyD genes. These genes are like postmen, helping to modify and send out the mature salP peptides. Except for two Type B strains, B4311 and B5258, which surprisingly showed inhibitory activity against L. monocytogenes. It turned out they had the lanT gene but not hlyD, proving that the LanT protein is crucial for sending out those microscopic bullets. Surprisingly, the Type B strains had a secret weapon too—an immunity protein. This made them resistant to salivaricin P, questioning the privilege of producing active bacteriocins in the competitive microbe world. The loss of export proteins wasn't consistent but scattered, hinting at the genetic flexibility of the repA-type megaplasmid and maybe a response to low nutritional competitors. In the grand scheme, these differences in salivaricin production have nothing to do with where the bacteria live—whether in broilers or laying hens. Both strains can hang out in the same place together. Plus, understanding how active salP works could help keep specific bacteria in check, be it in your food or farm animals.