190. Elucidation and biodiversity of bacterial communities within the phyllosphere of Humulus lupulus L.

Scott Britton (1), Mary Allen (2), Joseph Balnis (2), Peter Benzinger (2), Laura Grieneisen (3), Andrew Piefer (2); (1) Duvel Moortgat, NV, Breendonk, Belgium; (2) Hartwick College, Oneonta, NY, U.S.A.; (3) University of Notre Dame, Notre Dame, IL, U.S.A.

Yeast, Fermentation, and Microbiology

Microbial communities inhabiting the phyllosphere, the airborne locations of plants, have been shown to influence plant fitness, promote plant growth, aid in the suppression of disease, and affect the productivity of agricultural crops. However, a majority of prior investigations have been limited to the microbial communities associated with the leaf, the most prevalent structure within the phyllosphere. Although the flower is of considerable importance to overall reproductive success, the microbiota associated with these anatomical structures remains poorly understood. Our investigation identified members of the microbial community populating the cone, an inflorescence, and leaf of mature hops (Humulus lupulus L.), and subsequently compared the diversity with that present in the soil at the base of the plant. Characterization of the communities was carried out via the next-generation sequencing of polymerase-chain reaction-derived single amplicons (~460 bps) containing the V3/V4 hyper-variable region of 16S rRNA genes extracted and amplified from each sample. Results indicated that compared to the soil around the base the diversity existent on many of the hop cones and leaves was considerably less. The median number of phyla discovered to populate each sampling site were 25 for hop cones (n = 9), 22 for leaves (n = 4) and 47 for soils (n = 7). The two taxa most abundant on hop cones and leaves belong to the class Gammaproteobacteria, predominantly from the family Pseudomonadaceae, and the class Alphaproteobacteria, primarily from the family Sphingomonadaceae. The two classes represented medians of 55.98% and 22.54% of the sequences in cones and 43.69% and 22.95% of the sequences in leaves, respectively. Pseudomonas were also some of the most abundant, or most common, taxa identified in the microbial communities of flowers from the tomato (Solanum lycopersicum) and other plants. In contrast, the Gammaproteobacteria comprised only a small component of the communities from the leaves of Arabadopsis thaliana, clover, rice and soybean. The phylum Acidobacteria was also well represented in the hops cone and leaf communities but much less common in the flower communities of other plants. The intention of this study was to elucidate the microbial ecology associated with Humulus lupulus, to provide a reference source for bioprospecting that could improve the horticulture and performance of cultivars, and to contribute to the general understanding of the microbial ecology of the phyllosphere.

Scott Britton is a R&D scientist for Duvel Moortgat, NV (Breendonk, Belgium). He received a B.S. degree in biology from Utica College (Utica, NY), and an M.S. degree in biotechnology from the Johns Hopkins University (Baltimore, MD). He is an active member of the American Society for Microbiology and the American Society of Brewing Chemists. He also currently serves on the ASBC Board of Directors as chair of the Program Committee. His current research is primarily focused on microbial ecology and plant–microbe interactions.