Continuous cultivation of Lactobacillus brevis NCL912 for production of gamma-aminobutyric acid
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Continuous cultivation of Lactobacillus brevis NCL912 for production of gamma-aminobutyric acid Haixing Li & Ting Qiu & Xiaohua Liu & Yusheng Cao
Received: 13 November 2012 / Accepted: 2 January 2013 # Springer-Verlag Berlin Heidelberg and the University of Milan 2013
Abstract A continuous cultivation method for Lactobacillus brevis NCL912 to synthesize gamma-aminobutyric acid was developed in this work. Different dilution rates were evaluated for obtaining steady state in continuous cultivation. The results showed that steady state could be achieved at dilution rates from 0.08 to 0.12 h−1. The highest gammaaminobutyric acid productivity (5.11 g L−1 h−1) was obtained at dilution rate of 0.09 h−1. The kinetic models were established for continuous gamma-aminobutyric acid production by using the Monod equation for microbial growth, and the Luedeking–Piret equation for product formation. The microbial growth and product formation can be described by equations μ ¼ 0:1234CS =ð0:9338 þ CS Þ and QP ¼ 6:86 g g1 cell h1 , respectively. The production of gammaaminobutyric acid by L. brevis NCL912 was non-growthassociated. Keywords Gamma-aminobutyric acid . Lactobacillus brevis NCL912 . Continuous cultivation . Kinetic model
Findings Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the mammalian central nervous system (Jakobs et al. 1993; Ueno 2000) and has several important
Haixing Li and Ting Qiu contributed equally to this work. H. Li : T. Qiu : X. Liu : Y. Cao State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China H. Li : T. Qiu : X. Liu : Y. Cao (*) Sino-German Joint Research Institute, Nanchang University, Nanchang 330047, China e-mail: [email protected]
physiological functions (Wong et al. 2003; Hayakawa et al. 2004; Chuang et al. 2011; Al-Wadei et al. 2012). GABA has been a functional bioactive component in foods and pharmaceuticals. Many studies have focused on lactic acid bacterial (LAB) GABA production due to its naturalness and safety (Siragusa et al. 2007; Li and Cao 2010; Lyte 2011; Barrett et al. 2012). Batch fermentation (Komatsuzaki et al. 2005), fed-batch fermentation (Tamura et al. 2010), and immobilized cell technology (Choi et al. 2006) have been applied to improve LAB GABA production. These approaches have given final GABA concentrations of 115.70 g L−1 or below with productivities below 1.61 g L−1 h−1. L. brevis NCL912 was isolated from fermented food in our laboratory (Li et al. 2008), which could efficiently produce GABA in fed-batch fermentation (Li et al. 2010). Although the process provided high yield (103.72 g L−1), the GABA productivity was low (2.16 g L−1 h−1). Continuous culture can provide long-term stable high density cells (Bailey and Tahtiharju 2003; Malaviya et al. 2012) and therefore may realize a high rate of GABA formation for a long time. This work focused on the evaluation of the feasibility of continuous GABA production by L. brevis NCL912 using an automatic overflow continuous cultivation
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