Bernstein Hans C, McClure Ryan S, Thiel Vera, Sadler Natalie C, Kim Young-Mo, Chrisler William B, Hill Eric A, Bryant Donald A, Romine Margaret F, Jansson Janet K, Fredrickson Jim K, Beliaev Alexander S
Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA; The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington, USA.
Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA.
mSystems. 2017 Mar 7;2(2). doi: 10.1128/mSystems.00181-16. eCollection 2017 Mar-Apr.
The mechanisms by which microbes interact in communities remain poorly understood. Here, we interrogated specific interactions between photoautotrophic and heterotrophic members of a model consortium to infer mechanisms that mediate metabolic coupling and acclimation to partnership. This binary consortium was composed of a cyanobacterium, BP-1, which supported growth of an obligate aerobic heterotroph, strain A, by providing organic carbon, O, and reduced nitrogen. Species-resolved transcriptomic analyses were used in combination with growth and photosynthesis kinetics to infer interactions and the environmental context under which they occur. We found that the efficiency of biomass production and resistance to stress induced by high levels of dissolved O increased, beyond axenic performance, as a result of heterotrophic partnership. Coordinated transcriptional responses transcending both species were observed and used to infer specific interactions resulting from the synthesis and exchange of resources. The cyanobacterium responded to heterotrophic partnership by altering expression of core genes involved with photosynthesis, carbon uptake/fixation, vitamin synthesis, and scavenging of reactive oxygen species (ROS). This study elucidates how a cyanobacterial primary producer acclimates to heterotrophic partnership by modulating the expression levels of key metabolic genes. Heterotrophic bacteria can indirectly regulate the physiology of the photoautotrophic primary producers, resulting in physiological changes identified here, such as increased intracellular ROS. Some of the interactions inferred from this model system represent putative principles of metabolic coupling in phototrophic-heterotrophic partnerships.
微生物在群落中相互作用的机制仍知之甚少。在此，我们研究了一个模型聚生体中光合自养和异养成员之间的特定相互作用，以推断介导代谢耦合和适应共生关系的机制。这个二元聚生体由蓝细菌BP-1组成，它通过提供有机碳、氧气和还原态氮来支持专性好氧异养菌菌株A的生长。物种分辨转录组分析与生长和光合作用动力学相结合，以推断相互作用以及它们发生的环境背景。我们发现，由于异养共生关系，生物量生产效率和对高溶解氧诱导的胁迫的抗性提高，超过了纯培养性能。观察到跨越两个物种的协调转录反应，并用于推断由资源合成和交换产生的特定相互作用。蓝细菌通过改变参与光合作用、碳吸收/固定、维生素合成和活性氧（ROS）清除的核心基因的表达来响应异养共生关系。这项研究阐明了蓝细菌初级生产者如何通过调节关键代谢基因的表达水平来适应异养共生关系。异养细菌可以间接调节光合自养初级生产者的生理，导致此处确定的生理变化，如细胞内ROS增加。从这个模型系统推断出的一些相互作用代表了光养-异养共生关系中代谢耦合的推定原则。
