Centre for Marine Science and Innovation, The University of New South Wales, Sydney, New South Wales, Australia.
School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, New South Wales, Australia.
Appl Environ Microbiol. 2021 Sep 10;87(19):e0076921. doi: 10.1128/AEM.00769-21.
Phaeobacter inhibens 2.10 is an effective biofilm former on marine surfaces and has the ability to outcompete other microorganisms, possibly due to the production of the plasmid-encoded secondary metabolite tropodithietic acid (TDA). P. inhibens 2.10 biofilms produce phenotypic variants with reduced competitiveness compared to the wild type. In the present study, we used longitudinal, genome-wide deep sequencing to uncover the genetic foundation that contributes to the emergent phenotypic diversity in 2.10 biofilm dispersants. Our results show that phenotypic variation is not due to the loss of the plasmid that carries the genes for TDA synthesis but instead show that 2.10 biofilm populations become rapidly enriched in single nucleotide variations in genes involved in the synthesis of TDA. While variants in genes previously linked to other phenotypes, such as lipopolysaccharide production (i.e., ) and cellular persistence (i.e., ), also appear to be selected for during biofilm dispersal, the number and consistency of variations found for genes involved in TDA production suggest that this metabolite imposes a burden on 2.10 cells. Our results indicate a strong selection pressure for the loss of TDA in monospecies biofilm populations and provide insight into how competition (or a lack thereof) in biofilms might shape genome evolution in bacteria. Biofilm formation and dispersal are important survival strategies for environmental bacteria. During biofilm dispersal, cells often display stable and heritable variants from the parental biofilm. Phaeobacter inhibens is an effective colonizer of marine surfaces, in which a subpopulation of its biofilm dispersal cells displays a noncompetitive phenotype. This study aimed to elucidate the genetic basis of these phenotypic changes. Despite the progress made to date in characterizing the dispersal variants in , little is understood about the underlying genetic changes that result in the development of the specific variants. Here, phenotypic variation was linked to single nucleotide polymorphisms (SNPs), in particular in genes affecting the competitive ability of , including genes related to the production of the antibiotic tropodithietic acid (TDA) and bacterial cell-cell communication (e.g., quorum sensing). This work is significant as it reveals how the biofilm lifestyle might shape genome evolution in a cosmopolitan bacterium.
抑食金球藻 2.10 是海洋表面有效形成生物膜的生物，并且能够与其他微生物竞争，这可能是由于其质粒编码的次生代谢产物 Tropodithietic 酸（TDA）的产生。与野生型相比，抑食金球藻 2.10 生物膜产生的表型变体竞争力降低。在本研究中，我们使用纵向、全基因组深度测序来揭示导致 2.10 生物膜分散剂中出现新兴表型多样性的遗传基础。我们的研究结果表明，表型变异不是由于携带 TDA 合成基因的质粒丢失所致，而是表明 2.10 生物膜种群中与 TDA 合成相关的基因中迅速积累了单核苷酸变异。虽然与其他表型相关的基因（例如，脂多糖产生（即）和细胞持久性（即））的变体似乎在生物膜分散过程中也被选择，但参与 TDA 产生的基因中的变异数量和一致性表明该代谢物对 2.10 细胞造成了负担。我们的研究结果表明，在单种生物膜种群中强烈选择失去 TDA，并且深入了解了生物膜中的竞争（或缺乏竞争）如何塑造细菌的基因组进化。生物膜的形成和分散是环境细菌的重要生存策略。在生物膜分散过程中，细胞通常表现出与亲代生物膜稳定且可遗传的变体。抑食金球藻是海洋表面的有效定殖者，其生物膜分散细胞的亚群表现出非竞争性表型。本研究旨在阐明这些表型变化的遗传基础。尽管迄今为止在表征 中的分散变体方面取得了进展，但对于导致特定变体发展的潜在遗传变化知之甚少。在这里，表型变异与单核苷酸多态性（SNP）相关，特别是在影响 竞争能力的基因中，包括与抗生素 Tropodithietic 酸（TDA）和细菌细胞间通讯（例如，群体感应）相关的基因。这项工作意义重大，因为它揭示了生物膜生活方式如何塑造一种世界性细菌的基因组进化。
