Author(s): Fernandes, S. ; Dias, Bruna ; Belo, Isabel ; Lopes, Marlene
Date: 2023
Persistent ID: https://hdl.handle.net/1822/86534
Origin: RepositóriUM - Universidade do Minho
Subject(s): gluconic acid; sugarcane molasses; grape must; pressurized bioreactor; batch cultures; step-wise fed-batch cultures
BACKGROUND The profitable production of gluconic acid (GA), an organic acid extensively used in the food and beverages industries, relies on the use of cheap and available substrates with high sugar content. The high oxygen demand for the microbial conversion of glucose to GA is still a bottleneck of industrial production in conventional stirred tank reactors. Therefore, in this study, for the first time, it was studied the effect of increased air pressure up to 4 bar on the GA production and sugars consumption in batch and step-wise fed-batch cultures in sugarcane molasses (ScM) and grape must (GM) medium. RESULTS ScM and GM, by-products of the agro-food industry, proved to be adequate feedstocks to replace pure glucose in GA batch production by A. niger MUM 92.13. A 3-fold improvement in GA productivity was obtained in batch experiments carried out at 4 bar with ScM and GM, respectively, compared to those at 1 bar. Furthermore, the addition of two pulses of ScM, under pressurized conditions, increased the GA production, reaching a final concentration of 140 g·L-1. CONCLUSION This work proved that the use of total air pressure up to 4 bar is an effective approach to enhance GA productivity using ScM and GM as substrates in batch and step-wise fed-batch cultures. Also, this study provides a novel strategy for developing a biotechnological bioprocess for GA production by A. niger from low-cost and sugar-rich by-products performed in pressurized stirred tank reactors. This article is protected by copyright. All rights reserved.
