Program for Computational and Systems Biology, Memorial Sloan Kettering Cancer Center, New York, United States.
BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Lisboa, Portugal.
Elife. 2022 Nov 21;11:e76119. doi: 10.7554/eLife.76119.
Microbes have disproportionate impacts on the macroscopic world. This is in part due to their ability to grow to large populations that collectively secrete massive amounts of secondary metabolites and alter their environment. Yet, the conditions favoring secondary metabolism despite the potential costs for primary metabolism remain unclear. Here we investigated the biosurfactants that the bacterium makes and secretes to decrease the surface tension of surrounding liquid. Using a combination of genomics, metabolomics, transcriptomics, and mathematical modeling we show that the ability to make surfactants from glycerol varies inconsistently across the phylogenetic tree; instead, lineages that lost this ability are also worse at reducing the oxidative stress of primary metabolism on glycerol. Experiments with different carbon sources support a link with oxidative stress that explains the inconsistent distribution across the phylogeny and suggests a general principle: lineages produce surfactants if they can reduce the oxidative stress produced by primary metabolism and have excess resources, beyond their primary needs, to afford secondary metabolism. These results add a new layer to the regulation of a secondary metabolite unessential for primary metabolism but important to change physical properties of the environments surrounding bacterial populations.
微生物对宏观世界有着不成比例的影响。这在一定程度上是因为它们能够大量繁殖，集体分泌大量次生代谢物并改变环境。然而，尽管对初级代谢有潜在的成本，但有利于次级代谢的条件仍不清楚。在这里，我们研究了细菌产生并分泌的生物表面活性剂，以降低周围液体的表面张力。我们使用基因组学、代谢组学、转录组学和数学建模相结合的方法，表明从甘油中制造表面活性剂的能力在系统发育树上不一致；相反，失去这种能力的谱系在降低初级代谢对甘油的氧化应激方面也更差。不同碳源的实验支持与氧化应激的联系，这解释了在系统发育树上不一致的分布，并提出了一个一般原则：如果谱系能够降低初级代谢产生的氧化应激，并且有超出其初级需求的多余资源来负担次级代谢，那么它们就会产生表面活性剂。这些结果为调节一种对初级代谢非必需但对改变细菌种群周围环境物理性质很重要的次生代谢物增加了一个新的层面。
