Strain identity effects contribute more to Pseudomonas community functioning than strain interactions

Microbial communities can shape key ecological services, but the determinants of their functioning often remain little understood. While traditional research predominantly focuses on effects related to species identity (community composition and species richness), recent work increasingly explores the impact of species interactions on community functioning. Here, we conducted experiments with replicated small communities of fluorescent Pseudomonas bacteria to quantify the relative importance of strain identity versus interaction effects on two important functions, community productivity and siderophore production. By combining supernatant and competition assays with an established linear model method, we show that both factors have significant effects on functioning, but identity effects generally outweigh strain interaction effects. These results hold irrespective of whether strains interactions are inferred statistically or approximated experimentally. Our results have implications for microbiome engineering, as the success of approaches aiming to induce beneficial (probiotic) strain interactions will be sensitive to strain identity effects in many communities.

微生物群落可塑造关键生态系统服务，但其功能的决定机制往往仍未得到充分阐释。传统研究多聚焦于与物种属性（群落组成及物种丰富度）相关的效应，而近期研究愈发关注物种互作对群落功能的影响。本研究通过构建重复的荧光假单胞菌（Pseudomonas fluorescens）小型群落开展实验，以量化菌株属性与互作效应在两项核心功能——群落生产力与铁载体生成——中的相对重要性。我们将上清液测定、竞争实验与已建立的线性模型方法相结合，结果表明两类因素均对群落功能存在显著影响，但菌株属性效应通常强于菌株互作效应。无论菌株互作是通过统计推断还是实验近似得到，该结论均成立。本研究结果对微生物组工程具有重要启示：旨在诱导有益（益生）菌株互作的工程策略，在诸多群落中都会受到菌株属性效应的显著制约。