Title: Transcriptomic characterization of Caecomyces churrovis: a novel, non-rhizoid-forming lignocellulolytic anaerobic fungus

Abstract

Anaerobic gut fungi are the primary colonizers of plant material in the rumen microbiome, but are poorly studied due to a lack of characterized isolates. While most genera of gut fungi form extensive rhizoidal networks, which likely participate in mechanical disruption of plant cell walls, fungi within the Caecomyces genus do not possess these rhizoids. Here, we describe a novel fungal isolate, Caecomyces churrovis, which forms spherical sporangia with a limited rhizoidal network yet secretes a diverse set of carbohydrate active enzymes (CAZymes) for plant cell wall hydrolysis. Despite lacking an extensive rhizoidal system, C. churrovis is capable of growth on fibrous substrates like switchgrass, reed canary grass, and corn stover, although faster growth is observed on soluble sugars. Gut fungi have been shown to use enzyme complexes (fungal cellulosomes) in which CAZymes bind to non-catalytic scaffoldins to improve biomass degradation efficiency. However, transcriptomic analysis and enzyme activity assays reveal that C. churrovis relies more on free enzymes compared to other gut fungal isolates. Only 15% of CAZyme transcripts contain non-catalytic dockerin domains in C. churrovis, compared to 30% in rhizoid-forming fungi. Furthermore, C. churrovis is enriched in GH43 enzymes that provide complementary hemicellulose degrading activities, suggesting that a widermore » variety of these activities are required to degrade plant biomass in the absence of an extensive fungal rhizoid network. Overall, molecular characterization of a non-rhizoid-forming anaerobic fungus fills a gap in understanding the roles of CAZyme abundance and associated degradation mechanisms during lignocellulose breakdown within the rumen microbiome.« less

Authors:

Henske, John K.; Gilmore, Sean P.; Knop, Doriv; Cunningham, Francis J.; Sexton, Jessica A.; Smallwood, Chuck R.; Shutthanandan, Vaithiyalingam; Evans, James E.; Theodorou, Michael K.; O’Malley, Michelle A.

• Search DOE PAGES for author "O’Malley, Michelle A."
• Search DOE PAGES for ORCID "0000-0002-6065-8491"

Publication Date:

Wed Dec 20 00:00:00 EST 2017

Research Org.:

Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Univ. of California, Santa Barbara, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division; United States Dept. of Agriculture (USDA); US Army Research Office (ARO); National Science Foundation (NSF); Univ. of California, Los Angeles, CA (United States). California NanoSystems Institute (CNSI); Univ. of California, Santa Barbara, CA (United States); Harper Adams Univ., Newport (United Kingdom)

OSTI Identifier:

1618711

Alternate Identifier(s):

OSTI ID: 1434672; OSTI ID: 1485154; OSTI ID: 1518601

Report Number(s):

PNNL-SA-134108
Journal ID: ISSN 1754-6834; 305; PII: 997

Grant/Contract Number:  

SC0010352; MCB-1553721; W911NF-09-0001; AC05-76RL01830; DMR-1121053; CNS-0960316; DGE 114085

Resource Type:

Published Article

Journal Name:

Biotechnology for Biofuels

Additional Journal Information:

Journal Name: Biotechnology for Biofuels Journal Volume: 10 Journal Issue: 1; Journal ID: ISSN 1754-6834

Publisher:

Springer Science + Business Media

Country of Publication:

Netherlands

Language:

English

Subject:

09 BIOMASS FUELS; 59 BASIC BIOLOGICAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Anaerobic fungi; Neocallimastigomycota; Cellulase; Enzyme; Cellulosome