Optimization of process variables for acetoin production in a bioreactor using Taguchi orthogonal array design

Abiola Ezekiel Taiwo,Tafirenyika Nyamayaro Madzimbamuto,Tunde Victor Ojumu

doi:10.1016/j.heliyon.2020.e05103

Abiola Ezekiel Taiwo, Tafirenyika Nyamayaro Madzimbamuto + Show 1 more

Open Access

https://doi.org/10.1016/j.heliyon.2020.e05103

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Journal: Heliyon	Publication Date: Oct 1, 2020
Citations: 25	License type: cc-by

Affiliation: Cape Peninsula University of Technology

Abstract

Microbial production of acetoin is eco-friendly and inexpensive when compared with its synthetic methods of production. In the present findings, bioproduction of acetoin in a typical bioreactor was discussed with a view to ascertain the seemingly comparative advantage of bioreactor system over shake flask, and more importantly, to confirm that corn steep liquor can indeed adequately be used as a replacement for other organic nitrogen sources. Taguchi design was statistically used to optimized the fermentation process which resulted in a 3-fold increase in molar yield (83%) corresponding to a six-fold increase in acetoin concentration (63.43 g/L), as compared to a similar study conducted in a shake flask. Although agitation rate was observed to be the most controlling, the bioreactor may underperform at agitation rate greater than 300 rpm. The optimum parameters for acetoin production in this study were 300 rpm agitation, 1.5 slpm aeration, 2 days fermentation time, and pH 6.5. The results show that the commercial production of acetoin can be envisioned using a biological approach that may be of economic advantage.

Highlights

Flavour products have turned into inevitable supplements used in food industries (Teixeira et al, 2002)
The present study investigated the bioproduction of acetoin in a typical bioreactor a view to ascertain the seemingly comparative advantage of bioreactor system over shake flask, and to confirm that corn steep liquor can adequately be used as a replacement for other organic nitrogen sources
It was shown that 10.70 g/L of acetoin can be obtained in a shake flask experiment using Box-Behnken design in a response surface methodology which reveal 78.40 g/L, 15% w/v, and 2.70% v/v as optimum parameters for glucose concentration, corn steep liquor, and inoculum size as

Summary

Introduction

Flavour products have turned into inevitable supplements used in food industries (Teixeira et al, 2002). While Tian et al (2014) reported an optimum yield of 46 g/L acetoin from glucose, we have shown that corn steep liquor can supply all the microbial nitrogen requirements without the addition of yeast extract This approach may further reduce the production cost especially if commercial production is envisaged (Taiwo et al, 2018). The superior performance of bioreactor studies compared with shake flask can be attributed to the effective growth environment provided within bioreactor systems Variables such as dissolved oxygen concentration, pH, foaming level, agitation, temperature, gas mixture (nitrogen, oxygen, air, carbon dioxide) can be controlled in a bioreactor system, thereby giving it a comparative advantage over a shake flask system (Obom et al, 2013). Some of the shortcomings in shake flask studies do not apply to bioreactor studies

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