Ethylene glycol and glycolic acid production from xylonic acid by Enterobacter cloacae

Abstract Background: Biological routes for ethylene glycol production have been developed in recent years by constructing the synthesis pathways in different microorganisms. However, no microorganisms have been reported yet to produce ethylene glycol naturally. Results: Xylonic acid utilizing microorganisms were screened from natural environments, and an Enterobacter cloacae strain was isolated. The major metabolites of this strain were ethylene glycol and glycolic acid. However, the metabolites were switched to 2,3-butanediol, acetoin or acetic acid when this strain was cultured with other carbon sources. The metabolic pathway of ethylene glycol and glycolic acid synthesis from xylonic acid in this bacterium was identified. Xylonic acid was converted to 2-dehydro-3-deoxy-D-pentonate catalyzed by D-xylonic acid dehydratase. 2-Dehydro-3-deoxy-D-pentonate was converted to form pyruvate and glycolaldehyde, and this reaction was catalyzed by an aldolase. D-xylonic acid dehydratase and 2-dehydro-3-deoxy-D-pentonate aldolase were encoded by yjhG and yjhH, respectively. The two genes are part of the same operon and are located adjacent on the chromosome. Besides yjhG and yjhH, this operon contains four other genes. However, individually inactivation of these four genes had no effect on either ethylene glycol or glycolic acid production; both formed from glycolaldehyde. YqhD exhibits ethylene glycol dehydrogenase activity in vitro. However, a low level of ethylene glycol was still synthesized by E. cloacae ΔyqhD. Fermentation parameters for ethylene glycol and glycolic acid production by the E. cloacae strain were optimized, and aerobic cultivation at neutral pH were found to be optimal. In fed batch culture, 34 g/L of ethylene glycol and 13 g/L of glycolic acid were produced in 46 hours, with a total conversion ratio of 0.99 mol/mol xylonic acid.Conclusions: A novel route of xylose biorefinery via xylonic acid as an intermediate has been established.

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Ethylene glycol and glycolic acid production from xylonic acid by Enterobacter cloacae

10.21203/rs.2.19479/v1 ◽

2019 ◽

Author(s):

Zhongxi Zhang ◽

Yang Yang ◽

Yike Wang ◽

Jinjie Gu ◽

Xiyang Lu ◽

...

Keyword(s):

Ethylene Glycol ◽

Acid Production ◽

Glycolic Acid ◽

Carbon Sources ◽

Enterobacter Cloacae ◽

Acid Synthesis ◽

Natural Environments ◽

Acid Dehydratase ◽

Xylonic Acid

Abstract Background Biological routes of ethylene glycol production have been developed in recent years by constructing of the synthesis pathways in microorganisms. However, no microorganisms have been reported to produce ethylene glycol naturally.Results Xylonic acid utilizing microorganisms were screened from natural environments, and an Enterobacter cloacae strain was isolated. The major metabolites of this strain were ethylene glycol and glycolic acid. However, the metabolites were switched to 2,3-butanediol, acetoin or acetic acid when this strain was cultured with other carbon sources. The metabolic pathway of ethylene glycol and glycolic acid synthesis from xylonic acid in this bacterium was identified. Xylonic acid was converted to 2-dehydro-3-deoxy-D-pentonate with the catalysis of D-xylonic acid dehydratase. 2-Dehydro-3-deoxy-D-pentonate was converted to form pyruvate and glycolaldehyde, and this reaction was catalyzed by an aldolase. D-xylonic acid dehydratase and 2-dehydro-3-deoxy-D-pentonate aldolase were encoded by yjhG and yjhH , respectively. The two genes are part of the same operon and are located adjacent on the chromosome. Besides yjhG and yjhH , this operon contains four other genes. However, individually inactivation of these four genes had no effect on either ethylene glycol or glycolic acid production; both formed from glycolaldehyde. YqhD exhibits ethylene glycol dehydrogenase activity in vitro . However, a low level of ethylene glycol was still synthesized by E. cloacae Δ yqhD . Parameters for ethylene glycol and glycolic acid production by the E. cloacae strain were optimized, and aerobic cultivation at neutral pH were found to be optimal. In fed batch culture, 34 g/L of ethylene glycol and 13 g/L of glycolic acid were produced in 46 hours, with a total conversion ratio of 0.99 mol/mol xylonic acid.Conclusions A novel route of xylose biorefinery via xylonic acid as an intermediate has been established.

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Ethylene glycol and glycolic acid production from xylonic acid by Enterobacter cloacae

10.21203/rs.2.19479/v3 ◽

2020 ◽

Author(s):

Zhongxi Zhang ◽

Yang Yang ◽

Yike Wang ◽

Jinjie Gu ◽

Xiyang Lu ◽

...

Keyword(s):

Ethylene Glycol ◽

Acid Production ◽

Glycolic Acid ◽

Carbon Sources ◽

Enterobacter Cloacae ◽

Natural Environments ◽

Acid Dehydratase ◽

Xylonic Acid ◽

Fermentation Parameters

Abstract Background: Biological routes for ethylene glycol production have been developed in recent years by constructing the synthesis pathways in different microorganisms. However, no microorganisms have been reported yet to produce ethylene glycol naturally. Results: Xylonic acid utilizing microorganisms were screened from natural environments, and an Enterobacter cloacae strain was isolated. The major metabolites of this strain were ethylene glycol and glycolic acid. However, the metabolites were switched to 2,3-butanediol, acetoin or acetic acid when this strain was cultured with other carbon sources. The metabolic pathway of ethylene glycol synthesis from xylonic acid in this bacterium was identified. Xylonic acid was converted to 2-dehydro-3-deoxy-D-pentonate catalyzed by D-xylonic acid dehydratase. 2-Dehydro-3-deoxy-D-pentonate was converted to form pyruvate and glycolaldehyde, and this reaction was catalyzed by an aldolase. D-xylonic acid dehydratase and 2-dehydro-3-deoxy-D-pentonate aldolase were encoded by yjhG and yjhH, respectively. The two genes are part of the same operon and are located adjacent on the chromosome. Besides yjhG and yjhH, this operon contains four other genes. However, individually inactivation of these four genes had no effect on either ethylene glycol or glycolic acid production; both formed from glycolaldehyde. YqhD exhibits ethylene glycol dehydrogenase activity in vitro. However, a low level of ethylene glycol was still synthesized by E. cloacae ΔyqhD. Fermentation parameters for ethylene glycol and glycolic acid production by the E. cloacae strain were optimized, and aerobic cultivation at neutral pH were found to be optimal. In fed batch culture, 34 g/L of ethylene glycol and 13 g/L of glycolic acid were produced in 46 hours, with a total conversion ratio of 0.99 mol/mol xylonic acid.Conclusions: A novel route of xylose biorefinery via xylonic acid as an intermediate has been established.

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