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Title: The U.S. National Mall microbiome: A census of rhizosphere bacteria inhabiting landscape turf

item Crouch, Jo Anne
item CARTER, ZAKIYA - Eleanor Roosevelt High School
item Ismaiel, Ed - Ed
item ROBERTS, JOSEPH - University Of Maryland

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2017
Publication Date: 4/28/2017
Citation: Crouch, J.A., Carter, Z., Ismaiel, A., Roberts, J.A. 2017. The U.S. National Mall microbiome: A census of rhizosphere bacteria inhabiting landscape turf. Crop Science. 57:S341-S348.

Interpretive Summary: Small living organisms such as bacteria and fungi are abundant in soil. These microbes can substantially impact plant health, in both good and bad ways. In this research we conducted a census of the microbes that live in the lawn of the U.S. National Mall in Washington D.C., and compared them with those living in sod grass that will soon be planted at the National Mall when those lawns undergo renovations. The goal of this work was to learn what kinds of new microbes might be entering the National Mall during the lawn renovations. Over 1,600 unique microorganisms were identified using DNA fingerprinting. The microbes present were primarily of the type that rely on oxygen and live freely in the soil. Overall, the microbe census at the National Mall lawn was different from the sod grass microbe census. However, there was more in common than there were differences. Since there were so many microbes held in common, these findings show that the census of microbes living in the National Mall lawn may not change much after the new sod grass sod is planted. This information will be useful to agronomists, plant disease managers and other professionals that manage microbe populations to maintain and improve plant health.

Technical Abstract: Turf contains living assemblages of not only grass plants but also a plethora of microorganisms that may play critical roles in plant health through interactions such as predation, mutualism, and resource competition. Little is known about the turf microbiome, and how it might change in response to renovations such as new sod installation or overseeding. In this work, we survey bacteria inhabiting the rhizosphere of mature and recently renovated turf stands at the United States National Mall in Washington, D.C. We contrasted these data with the microbiomes of sod soon to be planted at the National Mall, and from the lawn of a nearby government facility. The soil-inhabiting microbiome was quantified through high-throughput next generation sequencing of the 16S rDNA. Over 1,600 operational taxonomic units were identified from 9.2 million sequence reads, of which 751 could be diagnosed at the genus level. Over 50% of the 751 identifiable bacterial taxa were members of the phylum Proteobacteria, predominately in the genus Rhodoplanes. Phenotypic mapping of predicted microbial function based on taxonomy showed all four locations were diverse, and in general, contained an abundance of gram-negative, aerobic, free-living thermophilic organisms. Ordination plots showed clustering of samples according to location. However, this pattern of differentiation between locations was not recapitulated using hierarchical clustering analysis, alpha diversity measurements, or ANOSIM, with no significant differences between locations identified. Given the commonality of bacterial communities between locations, these data suggest that the resident National Mall microbiome may not experience appreciable change due to the renovation process.