Comparative Assessment of Factors Involved in Acetoin Synthesis by Bacillus subtilis 168.

Pratibha Sharma,Santosh Noronha

doi:10.1155/2014/578682

Pratibha Sharma, Santosh Noronha

Open Access

https://doi.org/10.1155/2014/578682

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Journal: ISRN microbiology	Publication Date: Mar 10, 2014
Citations: 24	License type: CC BY 3.0

Affiliation: Indian Institute of Technology Bombay

Abstract

Acetoin is widely used as flavor agent and serves as a precursor for chemical synthesis. Here we focused on identifying the best physiological conditions (initial substrate concentrations, pH, temperature, and agitation) for enhanced acetoin accumulation by Bacillus subtilis 168. The optimal physiological conditions support maximum acetoin accumulation by minimizing byproduct (acetate and butanediol) synthesis and a maximum of 75% enhancement in acetoin yield could be achieved. Additionally, the effect of change in ALS (acetolactate synthase) and ALDC (acetolactate decarboxylase) activities was evaluated on acetoin accumulation. Increasing ALS and ALDC enzyme activities led to efficient utilization of pyruvate towards acetoin accumulation and about 80% enhancement in acetoin accumulation was observed.

Highlights

Acetoin is a four-carbon hydroxy-keto compound that is secreted by various microorganisms when grown on glycolytic substrates
In Bacillus subtilis, acetoin synthesis involves alsSD operon that consists of alsS and alsD genes encoding for acetolactate synthase (ALS; E.C. 2.2.1.6) and acetolactate decarboxylase (ALDC; E.C. 4.1.1.5), respectively [3]
Bacillus subtilis 168 was grown in Tris base medium (TSS) media provided with 2.5, 5.0, 10.0, 20.0, 50.0, and 100.0 glucose at maximum acetoin yield∗ (g/L) of glucose and acetoin synthesis was measured during the course of growth

Summary

Introduction

Acetoin is a four-carbon hydroxy-keto compound that is secreted by various microorganisms when grown on glycolytic substrates. It is widely used in the food and dairy industry as a preservative [1]. Acetoin is a secondary carbon source synthesized during sporulation in various organisms such as Bacillus subtilis [3, 4], Klebsiella terrigena [5], and Pelobacter carbinolicus [6]. Our current interest focuses on identification of important variables to enhance acetoin accumulation and minimizing byproduct formation For this purpose, we focused on two effects. We investigated the effect of ALS and ALDC enzyme activities on metabolites (glucose, pyruvate, acetate, acetoin, and 2,3butanediol) accumulation patterns

Materials and Methods

Results and Discussions

Conclusions