Figure 4.

Escherichia coli proliferation in different species correlates with host survival patterns and gut microbiota size. T. urticae, D. melanogaster and S. berlesei were infected with 5–100 CFUs of E. coli per individual and bacterial dynamics within the host was quantified daily for up to 4 days after infection. (a) In T. urticae, an increase in the number of CFUs in living individuals was observed over the course of 2 days. At 3 and 4 days (asterisk), only dead individuals were plated as there were no survivors, but the CFUs did not increase significantly. (b) For S. berlesei injection, the dynamics of E. coli growth was similar to that of D. melanogaster. (c) Gut microbiota is virtually absent in T. urticae as opposed to S. berlesei. Untreated mites (control) or treated with different protocols to remove bacteria from their surface (sterilized), from their gut (rifampicin) and from both their surface and gut (sterilized and rifampicin) were homogenized and plated on a Petri dish containing LB agar. T. urticae is colonized by two to three orders of magnitude less bacteria than S. berlesei. ***p < 0.001.