Effects of iron and mixed communities on two anaerobic lignin decomposing bacteria
EMSL Project ID
47923
Abstract
The fast growth, high efficiency and specificity of enzymes employed in bacterial anaerobic litter deconstruction makes these useful templates for improving biofuel production. There are few cultured representatives of anaerobic lignin degrading bacteria. Tropical forest soils decompose litter rapidly and completely with low and fluctuating redox potentials, making it likely that bacteria using oxygen-independent enzymes play an important role in decomposition. Iron likely facilitates this rapid C cycling, as a terminal electron acceptor that is abiotically regenerated under oxic fluctuations. Using two cultured representatives of anaerobic lignin-degrading bacteria, Enterobacter lignolyticus SCF1 and Tolumonas BRL6-1, we propose to characterize the effect of iron on lignin degradation in the presence of a cellulose-degrading consortia. Cellulose-degrading consortia are derived from same soils that the bacteria were isolated from: wet tropical forest soils of the El Yunque Experimental Forest LTER, Luquillo, Puerto Rico USA. Two consortia, one fermentative and one iron-reducing, were evolved anaerobically over multiple successive transfers on switchgrass as sole carbon source. According to functional and metagenomic data, added iron supported richer consortia with more lignin- and cellulose-degrading genes and higher specific enzyme activities. We propose studying a time course of lignocellulose degradation for the two anaerobic lignin degrading bacteria, with and without the consortia present, and with and without iron. Our specific aims are to:(1) apply transcriptomics and proteomics to define the enzymes and other regulatory machinery that these organisms use to degrade lignin with and without iron, and
(2) apply metabolomics to measure lignin degradation and monitor the use of lignin and iron as terminal electron acceptors that facilitate more efficient use of carbon.
At the time of the beginning of this project, we will have detailed data on a time course of growth of Enterobacter lignolyticus SCF1 and Tolumonas BRL6-1 on lignin as sole carbon source. This research is aimed at testing the hypotheses that iron increases lignin-degradation efficiency, and that interactions with complex community members will induce the expression of more or alternate enzymes with lower binding constants for substrates due to competition. Our preliminary data shows the advantages of a multi-omics approach, where we were able to complete partial pathways identified by genomics, and make new observations on coping with poor carbon availability. Resources used will include SOLiD Sequencer for transcriptomics, Mass Spectrometry for proteomics, NMR Spectrometry for metabolomics, and Mossbauer Spectrometry for measuring dissimilatory or assimilatory iron reduction. In addition to testing the role of iron in fueling rapid carbon cycling in wet tropical soils, identification of lignin-degrading pathways will show the role of bacteria among mixed communities in anaerobic decomposition. Genes encoding either novel lignin-degrading enzymes or stress tolerance of degradation by-products will be incorporated into the metabolic engineering approach of JBEI to develop more efficient consolidated bioprocessing of lignocellulosic biofuels or biodiesel.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2013-10-01
End Date
2015-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Chaput, Gina, Andrew F. Billings, Lani DeDiego, Roberto Orellana, Joshua N. Adkins, Carrie D. Nicora, Young-Mo Kim, Rosalie Chu, Blake Simmons, and Kristen M. DeAngelis. "Lignin induced iron reduction by novel sp., Tolumonas lignolytic BRL6-1." PloS one 15, no. 9 (2020): e0233823.