Several studies have investigated the diversity and certain processes driven by microbes within bromeliad tanks. The physiological capabilities of bromeliads, including increased capacity for amino acid and mineral uptake from the tank, are known (Benzing 1970 Winkler and Zotz 2009), but the specific metabolisms of resident bacteria, and their role in carbon cycling in the rainforest, have not been specifically elucidated. This creates an unusual aquatic habitat suspended in the canopy, allowing for long-term retention and decomposition of organic compounds, compared to soil (Pittl et al. Many species collect large amounts of water in the canopy by the formation of unique foliar arrangements, or "tanks" (Richardson 1999 Benzing 2000), thus these densities represent as much as 50,000 L suspended water in the canopy ha-1 (Fish 1983). Bromeliad average density has been estimated at 1000-100,000 ha-1 ground area, depending on the study (Sugden and Robins 1979 Richardson 1999). Plants from the family Bromeliaceae are prominent members of neotropical rain and cloud forests. These results suggest that bromeliad-associated betaproteobacteria may play an important role in the cycling of carbon in this unusual aquatic habitat. Metabolic activity profiles were overlapping between the Burkholderiales, isolated at pH 4, and the Neisseriales, isolated at pH 6, suggesting that plant material decomposition, which is presumably the underlying process sustaining the tank community and possibly the plant itself, occurs in the tanks at both pH extremes. Activity profiles for the isolates suggest pervasive capabilities for the breakdown of plant-sourced organics, including D-galacturonic acid, mannitol, D-xylose, and L-phenylalanine, also reflecting a niche dominated by decomposition of leaves from the overlying canopy, which become entrained in the tanks. Bromeliad-associated bacteria most closely related to Chromobacterium, Herbaspirillum, and Aquitalea were all isolated exclusively at pH 6, while Ralstonia, Cupriavidus, and three species of Burkholderia were isolated mostly at pH 4. Compared to close relatives, the isolates displayed high temperature and comparatively low pH optima, reflecting the tropical, acidic nature of the bromeliad tank. Isolates included eight species from the orders Neisseriales and Burkholderiales, with close relatives recovered previously from tropical soils, wetlands, freshwater, or in association with plants. Received: 3 November 2015 Revised: 15 January 2016 Accepted: 25 January 2016īetaproteobacteria were the most common isolates from the water-filled tank of a Costa Rican bromeliad. Braker (Occidental College, OISE-0526551), as well as the Undergraduate Research Center (Academic Student and Summer Research Projects), and a Faculty Enrichment grant from Occidental College to S.K.G. Tel: 3 Fax: (323) 341-4974 E-mail: Informationįunding for this project included, in part, a National Science Foundation grant to B. Goffredi, Biology Deptartment, Occidental College, 1600 Campus Rd, Los Angeles, CA 90041. Goffrediīiology Deptartment, Occidental College, Los Angeles, Californiaīetaproteobacteria, bromeliad, Costa Rica, decomposition, rainforest Jane Klanna, Alexandra McHenrya, Carin Montelongo & Shana K.
Decomposition of plant-sourced carbon compounds by heterotrophic betaproteobacteria isolated from a tropical Costa Rican bromeliad
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