Fig. 2.

Diversity in terms of gene copy number within the population. (A) Number of copies of a subset of genes having differential profiles between the dairy and non-dairy isolates. Strains are organized by population. (B) Distribution of the growth ratio, that is the max OD in the tested conditions normalized by the max OD obtained in glucose 2% condition, of the Kluyveromyces lactis strains with increasing concentration of lactose, according to the presence or the absence of the LAC4/LAC12 gene cluster. Wilcoxon–Mann–Whitney test was applied to assess the significance of the growth ratio difference between the two groups of strains. The level of significance is indicated as follows: ns, not significant, *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001.