Precursor Supply Strategy for Tetramethylpyrazine Production by Bacillus Subtilis on Solid-State Fermentation of Wheat B
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Precursor Supply Strategy for Tetramethylpyrazine Production by Bacillus Subtilis on Solid-State Fermentation of Wheat Bran Fei Hao & Qun Wu & Yan Xu
Received: 29 August 2012 / Accepted: 28 December 2012 / Published online: 11 January 2013 # Springer Science+Business Media New York 2013
Abstract Tetramethylpyrazine (TTMP) is a widely used flavoring additive with a nutty and roasted taste. Solid-state fermentation (SSF) of wheat bran for producing TTMP was studied with Bacillus subtilis CCTCC M208157, which was an exogenous precursor-independent TTMP-producing strain. Factors influencing endogenous precursor supply and TTMP formation in this strain were investigated. According to the findings, glucose and diammonium phosphate contributed to TTMP production but excess salts caused an inhibition on cell growth and TTMP formation. Then a two-step supply strategy was applied: 10 % glucose was added at the beginning of the process to allow acetoin formation, which was the precursor of TTMP, while 3 % diammonium phosphate was added only after acetoin accumulation reached its maximum. By applying this strategy, acetoin increased from 5.44 to 13.2 g/kg dry substrate (kgds), and consequently the yield of TTMP increased by 6.8 folds from 0.44 to 3.01 g/kgds. This was the first report of using a two-step supply strategy for TTMP production by SSF, which proved to be conducive to TTMP production in this strain. Keywords Tetramethylpyrazine . Solid-state fermentation . Bacillus subtilis . Two-step supply strategy
Introduction 2,3,5,6-Tetramethylpyrazine (TTMP) is a commercially important flavor additive in the food industry and proves to be an efficient medicament for several diseases [1–3]. Nowadays, TTMP is mainly produced through chemical synthetic methods. However, consumers prefer natural foodstuff out of concerns of their health and well-being [4]. Therefore, recently many efforts have been made to the development of biotechnological processes for TTMP production. F. Hao : Q. Wu : Y. Xu (*) State Key Laboratory of Food Science and Technology; Key Laboratory of Industrial Biotechnology, Ministry of Education; School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China e-mail: [email protected]
Appl Biochem Biotechnol (2013) 169:1346–1352
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Several researches have been done to improve the production of TTMP in solid-state and submerged fermentation (SmF) [5–7]. Microbial production of TTMP by utilizing glucose in SmF has proved to be a method of high productivity [8]. However, the large number of polluting effluents and the high energy consumption make the bioprocess cost-inefficient. Cheap materials and low-cost fermentation systems are to be explored to reduce the cost of microbial TTMP production. Recently, solid-state fermentation (SSF) has gained renewed interesting because of its efficient production of bulk chemicals and high-value enzymes and an advantage of process cost over SmF. The absence of liquid phase and a low substrate humidity level give full play to simple and small ferment
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