From PNNL: “Decoding Microbial Interactions”


December 2014
Web Publishing Services

Deep sequencing gives insights into mechanisms of microbial interactions

Results: As scientists strive to gain a systems-level understanding of microbial communities, their task grows increasingly more complex. Yet the benefits of doing this work can lead to new ways to engineer these amazing biological systems with significant implications for bioenergy, carbon sequestration, and bioremediation.

In ongoing work to integrate field investigations with well-controlled laboratory studies, scientists at Pacific Northwest National Laboratory grew two bacteria in a co-culture and applied deep transcriptome sequencing to study the physiological and genetic underpinnings driving interspecies interactions. They investigated the effect of co-cultivation and carbon flux directions on interactions between a salt-tolerant cyanobacterium, Synechococcus sp. PCC 7002 and a marine heterotroph, Shewanella putrefaciens W3-18-1. The results of this study, which appeared in The ISME Journal, provide novel and relevant insights into the physiological basis of microbial interactions.

Representative micrograph of Synechococcus sp. PCC7002 (red) and Shewanella sp. W3-18-1 (green) cell aggregates formed in a co-culture grown under carbon-limited aerobic chemostat conditions using lactate as the sole source of carbon.

Why It Matters: Phototrophs use energy from light to carry out various cellular metabolic processes, while heterotrophs use organic carbon for growth. In aquatic environments, an important class of interactions is based on cross-feeding and metabolite exchange, whereby photosynthetically fixed dissolved organic carbon (DOC) can elicit chemotactic responses that lead to spatial associations. This study provides initial insight into the complexity of photoautotrophic-heterotrophic interactions and brings new perspectives regarding their role in the robustness and stability of the association.

“Our experiments suggest that material and energy flows in microbial communities strongly affect the nature and direction of interactions between primary producers and heterotrophic consumers,” said Dr. Alex Beliaev, a microbiologist at PNNL and lead author of the publication. “Knowing the fundamental rules that govern the functioning of complex biological systems will inform science and policy challenges associated with environmental stewardship and climate change. It will also guide development of technical programs, including biodesign of stable microbial communities for bioenergy and environmental applications.”

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Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy National Laboratories, managed by the Department of Energy’s Office of Science. The main campus of the laboratory is in Richland, Washington.

PNNL scientists conduct basic and applied research and development to strengthen U.S. scientific foundations for fundamental research and innovation; prevent and counter acts of terrorism through applied research in information analysis, cyber security, and the nonproliferation of weapons of mass destruction; increase the U.S. energy capacity and reduce dependence on imported oil; and reduce the effects of human activity on the environment. PNNL has been operated by Battelle Memorial Institute since 1965.