Investigating Chitin Degrading Microbial Consortia in Bioelectrochemical Reactors
Abstract
Chitin, the second most prevalent renewable polymer in the ocean, is a vital carbon, nitrogen, and energy source to the marine biosphere [1]. Chitinolytic bacteria degrade the otherwise recalcitrant chitin polymer into biologically available forms via chitinases. Chitin is a major structural molecule for many benthic metazoans resulting in its deposition in anaerobic environments. While much is known about aerobic chitin degradation, there have been only a few studies on anaerobic chitin degradation. The benthic marine environment also hosts many insoluble electron acceptors not directly bioavailable to the microorganisms. Extracellular electron transfer (EET) is a metabolic strategy employed by certain microorganisms allowing the transfer of the electron to/from insoluble redox-active surfaces [2]. Since EET can be mimicked on electrode surfaces, it opens the door to using electrochemical techniques to enrich for and quantify the activities of microbial consortia from the subsurface.
Recently, we detected the presence of iron in the sediment core of a deep-sea whale fall site located in Monterey Bay, CA [3]. This provides us an ideal site to study the syntrophic interaction of chitin degrading organisms with iron-reducing microorganisms. Here, we describe our initial microcosm enrichment on poorly crystalline iron oxide followed by electrochemical enrichment at the redox potential of +220 mV vs SHE. Preliminary colorimetric assay and electrochemical studies point to the growth of chitin degraders, fermentors, and mineral reducing organisms. Molecular and 16S rRNA analysis are ongoing to assess the microbial diversity and metabolic flux dominant in these reactors. We will also investigate the spatially dependent interspecies interactions on the electrodes via stable isotope probing coupled with mRNA FISH. This study demonstrates the importance of energy flow and availability in the anoxic marine subsurface by using a variety of geochemical, genomic, and microscopy techniques on electrochemical enrichments. These enrichments act as a proxy for electron flow between the energy source - chitin - and an insoluble electron acceptor. [1] Beier et al, (2013); Front Microbiol. ; 4: 149. [2] Logan et al, (2019); Nature Reviews Microbiology; 17; 307-319 [3] Braby et al, (2007); Deep-Sea Research I; 54; 1773-1791.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP51D2115J
- Keywords:
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- 0448 Geomicrobiology;
- BIOGEOSCIENCES;
- 0495 Water/energy interactions;
- BIOGEOSCIENCES;
- 1829 Groundwater hydrology;
- HYDROLOGY;
- 5420 Impact phenomena;
- cratering;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS