Microbial heterotrophic production in an oligotrophic acidic geothermal lake: responses to organic amendments and terrestrial plant litter. Issue 3 (23rd June 2014)

• Record Type: Journal Article
• Authors: Wolfe, Gordon V.; Fitzhugh, Connor; Almasary, Areeje; Green, Adrian; Bennett, Patrick; Wilson, Mark; Siering, Patricia
• Is Part Of: FEMS microbiology ecology. Volume 89:Issue 3(2014)
• Page Start: 606
• Page End: 624
• Publication Date: 2014-06-23
• Subjects: Microbial ecology -- Periodicals; Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1574-6941.12360
• Languages: English
• ISSNs: 0168-6496

Abstract

<abstract abstract-type="main" id="fem12360-abs-0001"> <title>Abstract</title> <p>Boiling Springs Lake (BSL) is an oligotrophic, acidic geothermal feature where even very low levels of microbial heterotrophic production still exceed autotrophy. To test whether allochthonous leaf litter (LL) inputs fuel this excess, we quantified leaf litterfall, leaching and decomposition kinetics, and measured the impact of organic amendments on production, germination and cell growth, using pyrosequencing to track changes in microbial community composition. Coniferous leaves in BSL exhibited high mass loss rates during leaching and decomposition, likely due to a combination of chemical hydrolysis and contributions of both introduced and endemic microbes. We measured very low <italic>in situ</italic><sup>3</sup>H‐thymidine incorporation over hours by the dominant chemolithotroph <italic>Acidimicrobium</italic> (13–65 μg C L<sup>−1</sup> day<sup>−1</sup>), which was inhibited by simple C sources (acetate, glucose). Longer term incubations with additions of 0.01–0.02% complex C/N sources induced germination of the <italic>Firmicute Alicyclobacillus</italic> within 1–2 days, as well as growth of <italic>Acetobacteraceae</italic> after 3–4 days. LL additions yielded the opposite successional patterns of these r‐selected heterotrophs, boosting production to 30–150 μg C L<sup>−1</sup> day<sup>−1</sup>. Growth and germination studies suggest both prokaryotes and fungi likely consume allochthonous organics, and might be novel sources of lignocellulose‐degrading enzymes. A model of BSL's C budget supports the hypothesis that allochthonous inputs fuel seasonal microbial heterotrophy, but that dissolved organic C sources greatly exceed direct LL inputs.</p> </abstract>