A Series of Efficient Umbrella Modeling Strategies to Track Irradiation-Mutation Strains Improving Butyric Acid Production From the Pre-development Earlier Stage Point of View.

Li Cao,Xue-Zhen Wang,Yue Gao,Guang-Yuan Shu,Wei Cui,Ya-Nan Hu,Xiao-Peng Guo,Zong-Ping Xie,Xiang Zhou

doi:10.3389/fbioe.2021.609345

Abstract

Clostridium tyrobutyricum (C. tyrobutyricum) is a fermentation strain used to produce butyric acid. A promising new biofuel, n-butanol, can be produced by catalysis of butyrate, which can be obtained through microbial fermentation. Butyric acid has various uses in food additives and flavor agents, antiseptic substances, drug formulations, and fragrances. Its use as a food flavoring has been approved by the European Union, and it has therefore been listed on the EU Lists of Flavorings. As butyric acid fermentation is a cost-efficient process, butyric acid is an attractive feedstock for various biofuels and food commercialization products. 12C6+ irradiation has advantages over conventional mutation methods for fermentation production due to its dosage conformity and excellent biological availability. Nevertheless, the effects of these heavy-ion irradiations on the specific productiveness of C. tyrobutyricum are still uncertain. We developed non-structured mathematical models to represent the heavy-ion irradiation of C. tyrobutyricum in biofermentation reactors. The kinetic models reflect various fermentation features of the mutants, including the mutant strain growth model, butyric acid formation model, and medium consumption model. The models were constructed based on the Markov chain Monte Carlo model and logistic regression. Models were verified using experimental data in response to different initial glucose concentrations (0–180 g/L). The parameters of fixed proposals are applied in the various fermentation stages. Predictions of these models were in accordance well with the results of fermentation assays. The maximum butyric acid production was 56.3 g/L. Our study provides reliable information for increasing butyric acid production and for evaluating the feasibility of using mutant strains of C. tyrobutyricum at the pre-development phase.

Highlights

Butyrate (C4H8O2) possesses a structure of saturated tetracarboxylic acid; the name, butyric acid is derived from the Latin word for butter (Gutteridge, 1981; Ren et al, 1997; Bettelheim et al, 2012)
Factors influencing the irradiation-mutation strains that improve butyric acid production have been discussed based on the experimental results presented in this paper, and major modeling approaches concerning the estimation of butyric acid production have been critically estimated
Primary models described the evolution of irradiation-mutation strain amounts along with duration, and they can be further divided into two groups: deterministic model and stochastic model

Summary

Introduction

Butyrate (C4H8O2) possesses a structure of saturated tetracarboxylic acid; the name, butyric acid is derived from the Latin word for butter (Gutteridge, 1981; Ren et al, 1997; Bettelheim et al, 2012). Butyric acid and its acid salts are used in numerous commercial products, including food additives and flavors, antiseptics, cellulose-based plastic products, drug formulations, and aromatics (Zigová and Sturdik, 2000; Agler et al, 2011; Jiang et al, 2011). Butyric acid is generally present at concentrations of 82 mg/kg in candy, 60–270 mg/kg in chewing gum, 32 mg/kg in baked foods, 18 mg/kg in margarine, and 6.5 mg/kg in cold drinks. It has been used as a fishing bait additive due to its powerful odor. Many commercially available flavors that are used in carp bait use butyric as their ester base. Customers tend to choose food additives, flavors as well as fragrances containing natural ingredients (Ragauskas et al, 2006; Nigam and Singh, 2011; Zhou et al, 2013a,b)

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