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Pacific Northwest National Laboratory

Researchers Close the Knowledge Gap on Productivity – Diversity Relationships in a Multi-Kingdom Microbiome

Hot Lake (Oroville, WA) is a hypersaline lake which seasonally hosts complex benthic microbial mat systems.

The Science

Benthic aquatic habitats—in the sea, in freshwater lakes, and in hypersaline aquatic environments —support one of the most widespread ecosystems on earth. These habitats play critical roles in global biogeochemical cycling, and those operating in the euphotic zone (the layer close enough to the surface to receive light for photosynthesis) are major sources of productivity. Among these ecosystems are microbial mats—a thick, laminated collection of microbes belonging to different kingdoms of life that function as a living community and contribute to atmospheric oxygenation.

This paper examined if, and how, diversity of species within a representative benthic mat system affects its productivity and how 24-hour variations (known as diel cycles) in light availability influence output and microbiome mixture. 

The Impact

The results confirmed the researchers’ suspicions: Microbial productivity isinfluenced by both the number and relatedness of species existing within an ecosystem. However, within a multi-kingdom microbiome, such as the Hot Lake mat studied, there are contrasting types of relationships and their overall productivity is at least partially controlled by dynamic environmental factors such as solar energy inputs. The other portion of control, they say, is related to types of carbon sources that are available to the microbes.

This knowledge is another piece of the puzzle as we look at ways to manipulate microbes for functions such as biomass conversion, energy production, and more.

Summary

Photosynthetic microbial mats—those that use sunlight to synthesize nutrients from carbon dioxide and water—have had a profound influence in shaping our modern aquatic and terrestrial ecosystems through contribution of oxygen to the atmosphere. And yet knowledge gaps still remain about the correlations between diversity in communities of species and their subsequent productivity. 

Published in FEMS Microbiology Ecology, this paper sought to answer two questions: 1) How does species diversity relate to the rates of primary and heterotrophic productivity? and 2) How do diel (24- hour) variations in light-energy inputs influence productivity and microbiome diversity? 

To perform this investigation, the team developed microcosms from microbial mats (in the euphotic zone) found in the organic carbon replete waters of Hot Lake, located in northcentral Washington state. 

The results confirmed that microbial productivity isinfluenced by both the number and relatedness of species existing within an ecosystem. The exact relationships were influenced most strongly by the type of carbon substrates available for microbial life and availability of light over a 24-hour diel cycle.

Citation

Bernstein, H., et al. “Primary and heterotrophic productivity relate to multikingdom diversity in a hypersaline mat.” FEMS Microbiology Ecology, 93, 2017. [doi: 10.1093/femsec/ x121] 

Date: 
October 2017
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