Differential Salmonella survival against communities of intestinal amoebae

Abstract

Predation from intestinal amoebae may provide selective pressure for the maintenance of high genetic diversity at the Salmonella enterica rfb locus, whereby serovars better escape predators in particular environments depending on the O-antigens they express. Here, the hypothesis that amoebae from a particular intestinal environment collectively prefer one serovar over another is tested. Collections of Acanthamoeba, Tetramitus, Naegleria and Hartmannella were isolated from the intestinal tracts of several vertebrate hosts, including bullfrog tadpoles, goldfish, turtles and bearded dragons, and their feeding preferences were determined. Congeneric amoebae from the same environment had significantly similar feeding preferences. Strikingly, even unrelated amoebae -such as Naegleria and Tetramitus from goldfish -also had significantly similar feeding preferences. Yet amoebae isolated from different environments showed no similarity in prey choice. Thus, feeding preferences of amoebae appear to reflect their environment, not their taxonomic relationships. A mechanism mediating this phenotypic convergence is discussed.

Evidence for a Bacterial Lipopolysaccharide-Recognizing G-Protein-Coupled Receptor in the Bacterial Engulfment by Entamoeba histolytica

“…This result is supported by previous research indicating that E. histolytica primarily engulfs Gram-negative pathogens (30). Other investigators have also demonstrated selective engulfment of bacteria by amoebae based upon bacterial O-antigen (31,32). Therefore, other taxa of protozoa potentially express similar receptors for bacterial recognition.…”

The O-antigen mediates differential survival of Salmonella against communities of natural predators

“…In this model, predators in different microenvironments vary in their ability to recognize different antigenic types, thereby conferring high fitness to genotypes they avoid consuming, but only within their resident environment. Consistent with this model, diverse amoebae discriminate among bacterial prey on the basis of their O-antigen polysaccharides (Wildschutte et al, 2004;Wildschutte & Lawrence, 2007). Moreover, predators found in different environments have different feeding preferences (Wildschutte et al, 2004;Wildschutte & Lawrence, 2007).…”

“…Consistent with this model, diverse amoebae discriminate among bacterial prey on the basis of their O-antigen polysaccharides (Wildschutte et al, 2004;Wildschutte & Lawrence, 2007). Moreover, predators found in different environments have different feeding preferences (Wildschutte et al, 2004;Wildschutte & Lawrence, 2007). Regardless of their phylogenetic relatedness, predators isolated from the same environment share feeding preferences (Wildschutte & Lawrence, 2007), so that unrelated predators dwelling in the same environment avoid consuming the same antigenic classes of prey.…”

Persistence of Free-Living Protozoan Communities across Rearing Cycles in Commercial Poultry Houses

“…Food-borne pathogens like Campylobacter and Salmonella, important agents of (gastro)enteritis often related to the consumption of contaminated chicken meat, may survive, multiply, and be transported in the environment through association with various protozoan organisms (5,6,8,10,15,20,23,30,33,40,41). Some bacteria resist digestion by protozoans through adaptation of the intraprotozoan environment by alternation of the maturation pathway of food vacuoles (11,22,25), while others may survive or grow saprophytically in the extraprotozoan environment upon materials released from protozoan cells (2).…”