Local adaptation of a bacterium is as important as its presence in structuring a natural microbial community

s, and the few parallel changes that did occur affected genes of unknown functions, it is difficult to infer links between genomic and phenotypic changes. Unambiguous parallel changes occurred in the PFLU1093 and PFLU4198 genes, which were disrupted by insertions that led to frame-shifts. These genes encode a putative fimbrial usher protein and a putative sensory box GGDEF/EAL domain-containing protein that, in particular, are associated with the biogenesis of pili and the phosphorylation catalysis in response to detection of a chemical ligand or change in environment that initiate a change in cell activity, respectively.

Figure 1: Fitness of locally adapted SBW25.

Mean (±s.e.m.) selection coefficient of evolved SBW25 (after 48 days cultivation in sterile compost at 26 °C) determined by competing against its ancestor for 5 days in both sterile and unsterile compost. Note that selection coefficient (S) was calculated here by the difference between the estimated Malthusian parameter of the locally adapted SBW25 population (mLA) and the ancestral SBW25-lacZ strain (mAnct), where a value of zero indicates equal fitness.