Multiple (48 hour) transfers of 16S sequencing data (T0, T1, T3, T5) of our bacterial synthetic community screen, testing the (co-) invasive abilities of several bacterial strains when introduced to a stabilised bacterial kefir community (N = 6).

In this study, we introduced several (i.e., six unique) bacterial strains (i.e., our co-invading pool) to a kefir 'core' community (consisting of six kefir bacterial strains in the inoculum) stabilised after three 48-hour transfers (serial dilution of 1:20). For each transfer endpoint from which the 16S was sequenced (T0, T1, T3, T5), there are four individual plates with a unique plate design of locations of inoculation of our co-invader strains (single invasion & paired invasions). The difference between the four plates was A) the medium type, either defined minimal (DEF) or undefined rich (MRS-YPDA, 1:1), and B) whether the stabilised core community was present (+ COM, if not: just the monocultures and paired co-cultures, called the Binary interactions plate, BIN). This study sheds light on the phenomenon of co-invasion: differential invasive success if invading together with other bacteria than if invading alone.