Isolation, Identification, and Optimization of [gamma]-Aminobutyric Acid -Producing Bacillus cereus Strain KBC from a Commercial Soy Sauce moromi in Submerged-Liquid Fermentation

• Published in: Processes Vol. 8; no. 6
• Main Authors: Wan-Mohtar, Wan Abd Al Qadr Imad, Sohedein, Mohamad Nor Azzimi, Ibrahim, Mohamad Faizal, Kadir, Safuan Ab, Suan, Ooi Poh, Loen, Alan Wong Weng, Sassi, Soumaya, Ilham, Zul
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.06.2020
• Subjects: Bacillus cereus; Chemical properties; Fermentation; GABA; Observations; Soy sauce; United Kingdom
• ISSN: 2227-9717; 2227-9717
• DOI: 10.3390/pr8060652

A new high [gamma]-aminobutyric acid (GABA) producing strain of Bacillus cereus was successfully isolated from soy sauce moromi. This B. cereus strain named KBC shared similar morphological characteristics (Gram-positive, rod-shaped) with the reference B. cereus. 16S rRNA sequence of B. cereus KBC was found to be 99% similar with B. cereus strain OPWW1 under phylogenetic tree analysis. B. cereus KBC cultivated in unoptimized conditions using De Man, Rogosa, Sharpe (MRS) broth was capable of producing 523.74 mg [L.sup.-1] of GABA within five days of the cultivation period. By using response surface methodology (RSM), pH level, monosodium glutamate (MSG) concentration and temperature were optimized for a high concentration of GABA production. The pH level significantly influenced the GABA production by B. cereus KBC with p-value = 0.0023. GABA production by B. cereus KBC under the optimized condition of pH 7, MSG concentration of 5 g [L.sup.-1] and temperature of 40 [degrees]C resulted in GABA production of 3393.02 mg [L.sup.-1], which is 6.37-fold higher than under unoptimized conditions. Overall, this study has shown that B. cereus KBC isolated from soy sauce moromi is capable of producing a high concentration of GABA together with the optimal fermentation conditions that have been statistically analysed using RSM.