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.com
Volume 7, Issue 6 (Suppl)
J Bacteriol Parasito
ISSN: 2155-9597 JBP, an open access journal
Microbiology 2016
November 28-29, 2016
November 28-29, 2016 Valencia, Spain
7
th
World Congress on
Microbiology
Philips Akinwole et al., J Bacteriol Parasitol 2016, 7:6 (Suppl)
http://dx.doi.org/10.4172/2155-9597.C1.026Consumption of terrestrial dissolved organic carbon in microbial mesocosm
Philips Akinwole
1
, H Gandhi
2
, P H Ostrom
2
, L Kaplan
3
and
R H Findlay
1
1
University of Alabama, USA
2
Michigan State University, USA
3
Stroud Water Research Center, USA
D
issolved organic carbon (DOC) is the largest organic carbon pool in lotic systems. Current paradigms describing terrestrial
DOC in streams depict DOC as both an important carbon and energy source for microorganisms and containing large amounts
of chemical and biological refractory humic substances. To better evaluate the reliance of streammicroorganisms on terrestrial DOC,
we produced
13
C-labeled DOC by leaching composted
13
C-labelled tulip poplar leaves and twigs in soil columns for 3 months and
then leaching the soil with water. This process yields
13
C-labeled DOC with size and liability fractions approximating stream water
DOC. To determine the microbial groups actively using stream water DOC we incubated streambed sediments in recirculating
mesocosm chambers amended with
13
C-labeled DOC and examined
13
C incorporation into microbial phospholipid fatty acids.
Prokaryotes comprised 61% of the mesocosm microbial community and consisted of aerobic, facultative anaerobic and anaerobic
bacteria while microeukaryotes comprised the remaining 39%. Comparison by principal component analysis of the microbial
communities in stream sediments and stream sediments incubated with or without
13
C-labeled humic DOC showed our mesocosm-
based experimental design was sufficiently robust to investigate the use of
13
DOC by sediment microbial communities. After 48 hours
of incubation, phospholipid fatty acids i15:0, 16:0, 16:1w9, 18:1w9c, 18:1w7c (aerobic/facultative anaerobic bacterial biomarkers)
and 20:4w6, 20:5w3 (microeukaryotic biomarkers) showed increased abundance of
13
C. This suggests that the hetero organotrophic
bacteria actively utilized the
13
DOC and that microeukaryotic predators consumed those bacteria. These findings indicate that DOC,
although generally considered refractory and poorly utilized by microbiota, substantially contributes to the energy and carbon flow
in aquatic ecosystems.
Biography
Philips Akinwole is a Senior Researcher at the Department of Biological Sciences, University of Alabama, USA.
poakinwole@crimson.ua.edu