Abstract
The catabolic fate of the major monomeric sugar of red macroalgae, 3,6-anhydro-L-galactose (AHG), is completely unknown in any organisms. AHG is not catabolized by ordinary fermentative microorganisms, and it hampers the utilization of red macroalgae as renewable biomass for biofuel and chemical production. In this study, metabolite and transcriptomic analyses of Vibrio sp., a marine bacterium capable of catabolizing AHG as a sole carbon source, revealed two key metabolic intermediates of AHG, 3,6-anhydrogalactonate (AHGA) and 2-keto-3-deoxy-galactonate; the corresponding genes were verified in vitro enzymatic reactions using their recombinant proteins. Oxidation by an NADP<sup>+</sup>-dependent AHG dehydrogenase and isomerization by an AHGA cycloisomerase are the two key AHG metabolic processes. This newly discovered metabolic route was verified in vivo by demonstrating the growth of Escherichia coli harbouring the genes of these two enzymes on AHG as a sole carbon source. Also, the introduction of only these two enzymes into an ethanologenic E.coli strain increased the ethanol production in E.coli by fermenting both AHG and galactose in an agarose hydrolysate. These findings provide not only insights for the evolutionary adaptation of a central metabolic pathway to utilize uncommon substrates in microbes, but also a metabolic design principle for bioconversion of red macroalgal biomass into biofuels or industrial chemicals.
| Original language | English |
|---|---|
| Pages (from-to) | 1677-1688 |
| Number of pages | 12 |
| Journal | Environmental Microbiology |
| Volume | 17 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 2015 May 1 |
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ASJC Scopus subject areas
- Microbiology
- Ecology, Evolution, Behavior and Systematics
Cite this
The novel catabolic pathway of 3,6-anhydro-L-galactose, the main component of red macroalgae, in a marine bacterium. / Yun, Eun Ju; Lee, Saeyoung; Kim, Hee Taek; Pelton, Jeffrey G.; Kim, Sooah; Ko, Hyeok Jin; Choi, In-Geol; Kim, Kyoung Heon.
In: Environmental Microbiology, Vol. 17, No. 5, 01.05.2015, p. 1677-1688.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The novel catabolic pathway of 3,6-anhydro-L-galactose, the main component of red macroalgae, in a marine bacterium
AU - Yun, Eun Ju
AU - Lee, Saeyoung
AU - Kim, Hee Taek
AU - Pelton, Jeffrey G.
AU - Kim, Sooah
AU - Ko, Hyeok Jin
AU - Choi, In-Geol
AU - Kim, Kyoung Heon
PY - 2015/5/1
Y1 - 2015/5/1
N2 - The catabolic fate of the major monomeric sugar of red macroalgae, 3,6-anhydro-L-galactose (AHG), is completely unknown in any organisms. AHG is not catabolized by ordinary fermentative microorganisms, and it hampers the utilization of red macroalgae as renewable biomass for biofuel and chemical production. In this study, metabolite and transcriptomic analyses of Vibrio sp., a marine bacterium capable of catabolizing AHG as a sole carbon source, revealed two key metabolic intermediates of AHG, 3,6-anhydrogalactonate (AHGA) and 2-keto-3-deoxy-galactonate; the corresponding genes were verified in vitro enzymatic reactions using their recombinant proteins. Oxidation by an NADP+-dependent AHG dehydrogenase and isomerization by an AHGA cycloisomerase are the two key AHG metabolic processes. This newly discovered metabolic route was verified in vivo by demonstrating the growth of Escherichia coli harbouring the genes of these two enzymes on AHG as a sole carbon source. Also, the introduction of only these two enzymes into an ethanologenic E.coli strain increased the ethanol production in E.coli by fermenting both AHG and galactose in an agarose hydrolysate. These findings provide not only insights for the evolutionary adaptation of a central metabolic pathway to utilize uncommon substrates in microbes, but also a metabolic design principle for bioconversion of red macroalgal biomass into biofuels or industrial chemicals.
AB - The catabolic fate of the major monomeric sugar of red macroalgae, 3,6-anhydro-L-galactose (AHG), is completely unknown in any organisms. AHG is not catabolized by ordinary fermentative microorganisms, and it hampers the utilization of red macroalgae as renewable biomass for biofuel and chemical production. In this study, metabolite and transcriptomic analyses of Vibrio sp., a marine bacterium capable of catabolizing AHG as a sole carbon source, revealed two key metabolic intermediates of AHG, 3,6-anhydrogalactonate (AHGA) and 2-keto-3-deoxy-galactonate; the corresponding genes were verified in vitro enzymatic reactions using their recombinant proteins. Oxidation by an NADP+-dependent AHG dehydrogenase and isomerization by an AHGA cycloisomerase are the two key AHG metabolic processes. This newly discovered metabolic route was verified in vivo by demonstrating the growth of Escherichia coli harbouring the genes of these two enzymes on AHG as a sole carbon source. Also, the introduction of only these two enzymes into an ethanologenic E.coli strain increased the ethanol production in E.coli by fermenting both AHG and galactose in an agarose hydrolysate. These findings provide not only insights for the evolutionary adaptation of a central metabolic pathway to utilize uncommon substrates in microbes, but also a metabolic design principle for bioconversion of red macroalgal biomass into biofuels or industrial chemicals.
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U2 - 10.1111/1462-2920.12607
DO - 10.1111/1462-2920.12607
M3 - Article
VL - 17
SP - 1677
EP - 1688
JO - Environmental Microbiology
JF - Environmental Microbiology
SN - 1462-2912
IS - 5
ER -