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Appl Microbiol Biotechnol. 2017 Mar;101(6):2603-2618. doi: 10.1007/s00253-017-8091-1. Epub 2017 Jan 12.

Characterization of four endophytic fungi as potential consolidated bioprocessing hosts for conversion of lignocellulose into advanced biofuels.

Author information

1
Biomass Science and Conversion Technologies, Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94551, USA. whwu@ucdavis.edu.
2
Biomass Science and Conversion Technologies, Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94551, USA.
3
Department of Energy Joint Genome Institute, Walnut Creek, CA, USA.
4
CNRS, Aix-Marseille University, AFMB, Marseille, France.
5
Department of Biological Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.
6
Biomass Science and Conversion Technologies, Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94551, USA. jmgladden@lbl.gov.
7
Joint BioEnergy Institute, Emeryville, CA, USA. jmgladden@lbl.gov.

Abstract

Recently, several endophytic fungi have been demonstrated to produce volatile organic compounds (VOCs) with properties similar to fossil fuels, called "mycodiesel," while growing on lignocellulosic plant and agricultural residues. The fact that endophytes are plant symbionts suggests that some may be able to produce lignocellulolytic enzymes, making them capable of both deconstructing lignocellulose and converting it into mycodiesel, two properties that indicate that these strains may be useful consolidated bioprocessing (CBP) hosts for the biofuel production. In this study, four endophytes Hypoxylon sp. CI4A, Hypoxylon sp. EC38, Hypoxylon sp. CO27, and Daldinia eschscholzii EC12 were selected and evaluated for their CBP potential. Analysis of their genomes indicates that these endophytes have a rich reservoir of biomass-deconstructing carbohydrate-active enzymes (CAZys), which includes enzymes active on both polysaccharides and lignin, as well as terpene synthases (TPSs), enzymes that may produce fuel-like molecules, suggesting that they do indeed have CBP potential. GC-MS analyses of their VOCs when grown on four representative lignocellulosic feedstocks revealed that these endophytes produce a wide spectrum of hydrocarbons, the majority of which are monoterpenes and sesquiterpenes, including some known biofuel candidates. Analysis of their cellulase activity when grown under the same conditions revealed that these endophytes actively produce endoglucanases, exoglucanases, and β-glucosidases. The richness of CAZymes as well as terpene synthases identified in these four endophytic fungi suggests that they are great candidates to pursue for development into platform CBP organisms.

KEYWORDS:

CAZy; Consolidated bioprocessing; Endophyte; Ligninolytic enzymes; Terpene; Volatile organic compound

PMID:
28078400
DOI:
10.1007/s00253-017-8091-1
[Indexed for MEDLINE]

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