Open Access

ARTICLE

Mannonic Acid and Bio-Ethanol Production from Konjac Using a Two-Step Bioprocess with Candida Shehatae and Gluconobacter Oxydans

Jianglin Zhao¹, Xiaotong Zhang¹, Weiwei Lei¹, Xingqi Ji¹, Xin Zhou^1,2,*, Yong Xu^1,2

1 College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, China
2 Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing, 210037, China

* Corresponding Author: Xin Zhou. Email:

Journal of Renewable Materials 2020, 8(1), 79-88. https://doi.org/10.32604/jrm.2020.08761

Received 05 October 2019; Accepted 25 October 2019; Issue published 01 January 2020

Abstract

Amorphophallus konjac is rich in glucomannan, which can be hydrolyzed into glucose and mannose, thereby acting as an economic raw material for the acquisition of glucose and mannose. The total sugar yield was 91.2% when konjac powder was treated with 0.75% hydrochloric acid at 121°C for 1 h. Thus, dilute acid hydrolysates of konjac powder were used as a carbon source for obtaining value-added products. Here we showed that the microbial production of ethanol and mannonic acid was obtained by employing Candida shehatae (C. shehatae) and Gluconobacter oxydans (G. oxydans). Through a step-by-step bioprocess, glucose is the first selectively converted to ethanol by C. shehatae, which enables G. oxydans-mediated biocatalysis of mannose to mannonic acid. Finally, approximately 100 g ethanol and 340 g mannonic acid were produced starting from 1 kg refined konjac powder. The results demonstrated the feasibility of this bioconversion method for producing mannonic acid starting from crude hydrolysates of konjac powder.

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