Pseudomonas aeruginosa tends to be among the dominant species in multi-species bacterial consortia in diverse environments. To understand P. aeruginosa’s physiology and interactions with co-existing bacterial species in different conditions, we established physiologically reproducible 18 species communities, and found that P. aeruginosa dominated in mixed-species biofilm communities but not in planktonic communities. P. aeruginosa’s H1 type VI secretion system was highly induced in mixed-species biofilm consortia, compared with its monospecies biofilm, which was further demonstrated to play a key role in P. aeruginosa's enhanced fitness over other bacterial species. In addition, the type IV pili and Psl exopolysaccharide were required for P. aeruginosa to compete with other bacterial species in the biofilm community. Our study showed that the physiology of P. aeruginosa is strongly affected by interspecies interactions, and both biofilm determinants and type VI secretion system contribute to higher P. aeruginosa's fitness over other species in complex biofilm communities.

铜绿假单胞菌往往是不同环境中多物种细菌群落中的优势物种之一。为了了解铜绿假单胞菌的生理学以及在不同条件下与共存细菌物种的相互作用，我们建立了生理上可重复的18个物种群落，并发现铜绿假单胞菌在混合物种生物膜群落中占主导地位，但在浮游生物群落中不占主导地位。与单一物种生物膜相比，铜绿假单胞菌的H1 VI 型分泌系统在混合物种生物膜群落中被高度诱导，这进一步证明在铜绿假单胞菌相对于其他细菌物种的适应性增强中发挥着关键作用。此外，铜绿假单胞菌需要 IV 型菌毛和 Psl 胞外多糖来与生物膜群落中的其他细菌物种竞争。我们的研究表明，铜绿假单胞菌的生理学受到种间相互作用的强烈影响，生物膜决定因素和VI型分泌系统都有助于铜绿假单胞菌在复杂的生物膜群落中比其他物种具有更高的适应性。