this study evaluated the effects of drinking thyme essence (dte) (zero, 0.10, 0.15 and 0.20 ml/l) on growth performance, immune response and changing of intestinal bacterial population in broiler chickens. a total number of 500 day old male broiler chicks (ross 308), were randomly assigned to 4 treatments with 5 replicates and 25 chickens per each, based on a completely randomized design (crd)....

Recently, Lenski et al have carried out an experiment on bacterial evolution. Their findings support the theory of punctuated equilibrium in biological evolution. We show that the M=2 Bak-Sneppen model can explain some of the experimental results in a qualitative manner. There are two major schools of thought in evolutionary biology: gradualism which implies continuous evolutionary changes and ...

Persistence is a prime example of phenotypic heterogeneity, where a microbial population splits into two distinct subpopulations with different growth and survival properties as a result of reversible phenotype switching. Specifically, persister cells grow more slowly than normal cells under unstressed growth conditions, but survive longer under stress conditions such as the treatment with bact...