Growth and break-up of methanogenic granules suggests mechanisms for biofilm and community development

Trego, Anna Christine, Galvin, Evan, Sweeney, Conor, Dunning, Sinéad, Murphy, Cillian, Mills, Simon, Nzeteu, Corine, Quince, Christopher, Connelly, Stephanie, Ijaz, Umer Zeeshan and Collins, Gavin (2020) Growth and break-up of methanogenic granules suggests mechanisms for biofilm and community development. Frontiers in Microbiology, 11. ISSN 1664-302X

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Abstract

Methanogenic sludge granules are densely packed, small, spherical biofilms found in anaerobic digesters used to treat industrial wastewaters, where they underpin efficient organic waste conversion and biogas production. Each granule theoretically houses representative microorganisms from all of the trophic groups implicated in the successive and interdependent reactions of the anaerobic digestion (AD) process. Information on exactly how methanogenic granules develop, and their eventual fate will be important for precision management of environmental biotechnologies. Granules from a full-scale bioreactor were size-separated into small (0.6–1 mm), medium (1–1.4 mm), and large (1.4–1.8 mm) size fractions. Twelve laboratory-scale bioreactors were operated using either small, medium, or large granules, or unfractionated sludge. After >50 days of operation, the granule size distribution in each of the small, medium, and large bioreactor sets had diversified beyond—to both bigger and smaller than—the size fraction used for inoculation. Interestingly, extra-small (XS; <0.6 mm) granules were observed, and retained in all of the bioreactors, suggesting the continuous nature of granulation, and/or the breakage of larger granules into XS bits. Moreover, evidence suggested that even granules with small diameters could break. “New” granules from each emerging size were analyzed by studying community structure based on high-throughput 16S rRNA gene sequencing. Methanobacterium, Aminobacterium, Propionibacteriaceae, and Desulfovibrio represented the majority of the community in new granules. H2-using, and not acetoclastic, methanogens appeared more important, and were associated with abundant syntrophic bacteria. Multivariate integration (MINT) analyses identified distinct discriminant taxa responsible for shaping the microbial communities in different-sized granules.

Item Type:	Article
Additional Information:	Acknowledgements: The authors thank NVP Energy for providing anaerobic sludge granules. Funding Information: SC was supported by the Engineering and Physical Sciences Research Council, United Kingdom (EP/J00538X/1). CQ was funded by an MRC fellowship MR/M50161X/1 as part of the CLoud Infrastructure for Microbial Genomics (CLIMB) consortium MR/L015080/1. CM was supported by Erasmus and by the University of Turin and NUI Galway. UI was funded by NERC IRF NE/L011956/1. GC, SM, and AT were supported by a European Research Council Starting Grant (3C-BIOTECH 261330) and by a Science Foundation Ireland Career Development Award (17/CDA/4658) to GC. AT was further supported by a Thomas Crawford Hayes bursary from NUI Galway, and a Short-Term Scientific Mission grant through the EU COST Action 1302.
Uncontrolled Keywords:	anaerobic digestion,biofilms,methanogens,microbial communities,sludge granules,wastewater,microbiology,microbiology (medical) ,/dk/atira/pure/subjectarea/asjc/2400/2404
Faculty \ School:	Faculty of Science > School of Biological Sciences
Related URLs:	http://www.scopus.com/inward/record.url?...
Depositing User:	LivePure Connector
Date Deposited:	08 Sep 2022 13:30
Last Modified:	25 Sep 2024 16:43
URI:	https://ueaeprints.uea.ac.uk/id/eprint/87968
DOI:	10.3389/fmicb.2020.01126

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