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Title: Simultaneous depolymerization and fermentation of lignin into value-added products by the marine protist, Thraustochytrium striatum

Abstract

Biodegradation of lignin has been focused on bacteria and fungi, but little information is available on lignin biotransformation with marine protists. In this paper, kraft pine lignin was used as a carbon source for a newly recognized and patented lignin degrader, Thraustochytrium striatum HB. The fermentation medium was optimized in terms of nitrogen source and trace elements. The results showed NH4Cl was the best nitrogen source to enhance lignin consumption from 3 (for yeast extract or peptone) to 17%, while the utilization of yeast extract or peptone was found to inhibit lignin consumption by T. striatum HB. The presence of trace elements and vitamins improved lignin utilization from 17 to 25% by inducing the production of lignolytic enzymes. Different lignin depolymerization methods, including laccase, fungal secretome and Fenton reagent were used to enhance lignin fermentation. In the presence of laccase, both cell growth and lignin consumption were improved, and it was found that different laccases had different working mechanisms. Enzymatic depolymerization resulted in 25–30% lignin degradation, slightly higher than that (22%) from Fenton reagent. NMR analysis indicated that the fungus-derived laccase primarily worked on the breakdown of inter-unit linkages in lignin molecules, while plant-derived laccase possibly attacked the aromatic ringmore » structures. With the function of laccase, more low-molecular-weight lignin fragments can be generated, and laccase-catalyzing reaction would direct the equilibrium toward depolymerization by preventing repolymerization of small fragments. On the contrary, lignin peroxidase-dominant fungal secretome and Fenton reagent facilitated lignin degradation but not cell growth, possibly due to the generation of inhibitory compounds from lignin depolymerization by fungal secretome and Fenton reagent. The results from this research demonstrate that marine protists, such as T. striatum HB are a class of promising platform microorganisms for lignin valorization into valuable bioproducts.« less

Authors:
 [1];  [2]; ORCiD logo [3]; ORCiD logo [3];  [1]
  1. Kansas State Univ., Manhattan, KS (United States)
  2. Univ. of Tennessee, Knoxville, TN (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1606677
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Algal Research
Additional Journal Information:
Journal Volume: 46; Journal Issue: C; Journal ID: ISSN 2211-9264
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; Laccase; Lignin bioconversion; Lignolytic enzyme; Lignin depolymerization; Marine protist; Thraustochytrium striatum HB

Citation Formats

Li, Xiang, Li, Mi, Pu, Yunqiao Joseph, Ragauskas, Arthur J., and Zheng, Yi. Simultaneous depolymerization and fermentation of lignin into value-added products by the marine protist, Thraustochytrium striatum. United States: N. p., 2019. Web. doi:10.1016/j.algal.2019.101773.
Li, Xiang, Li, Mi, Pu, Yunqiao Joseph, Ragauskas, Arthur J., & Zheng, Yi. Simultaneous depolymerization and fermentation of lignin into value-added products by the marine protist, Thraustochytrium striatum. United States. doi:10.1016/j.algal.2019.101773.
Li, Xiang, Li, Mi, Pu, Yunqiao Joseph, Ragauskas, Arthur J., and Zheng, Yi. Tue . "Simultaneous depolymerization and fermentation of lignin into value-added products by the marine protist, Thraustochytrium striatum". United States. doi:10.1016/j.algal.2019.101773.
@article{osti_1606677,
title = {Simultaneous depolymerization and fermentation of lignin into value-added products by the marine protist, Thraustochytrium striatum},
author = {Li, Xiang and Li, Mi and Pu, Yunqiao Joseph and Ragauskas, Arthur J. and Zheng, Yi},
abstractNote = {Biodegradation of lignin has been focused on bacteria and fungi, but little information is available on lignin biotransformation with marine protists. In this paper, kraft pine lignin was used as a carbon source for a newly recognized and patented lignin degrader, Thraustochytrium striatum HB. The fermentation medium was optimized in terms of nitrogen source and trace elements. The results showed NH4Cl was the best nitrogen source to enhance lignin consumption from 3 (for yeast extract or peptone) to 17%, while the utilization of yeast extract or peptone was found to inhibit lignin consumption by T. striatum HB. The presence of trace elements and vitamins improved lignin utilization from 17 to 25% by inducing the production of lignolytic enzymes. Different lignin depolymerization methods, including laccase, fungal secretome and Fenton reagent were used to enhance lignin fermentation. In the presence of laccase, both cell growth and lignin consumption were improved, and it was found that different laccases had different working mechanisms. Enzymatic depolymerization resulted in 25–30% lignin degradation, slightly higher than that (22%) from Fenton reagent. NMR analysis indicated that the fungus-derived laccase primarily worked on the breakdown of inter-unit linkages in lignin molecules, while plant-derived laccase possibly attacked the aromatic ring structures. With the function of laccase, more low-molecular-weight lignin fragments can be generated, and laccase-catalyzing reaction would direct the equilibrium toward depolymerization by preventing repolymerization of small fragments. On the contrary, lignin peroxidase-dominant fungal secretome and Fenton reagent facilitated lignin degradation but not cell growth, possibly due to the generation of inhibitory compounds from lignin depolymerization by fungal secretome and Fenton reagent. The results from this research demonstrate that marine protists, such as T. striatum HB are a class of promising platform microorganisms for lignin valorization into valuable bioproducts.},
doi = {10.1016/j.algal.2019.101773},
journal = {Algal Research},
number = C,
volume = 46,
place = {United States},
year = {2019},
month = {12}
}

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This content will become publicly available on December 31, 2020
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