(465f) L-Lactate Production By a Potent Homofermentative Bacillus Sp. BC-001

A novel Bacillus sp. BC-001 was found as a potent thermotolerant and homofermentative L-lactic acid production. This strain wasisolated from the natural resources in Thailand. From the screening fermentation in the flask culture, this novel strain produced L-lactate with high yield and productivity during batch cultivation of glucose (0.96 g/g and 0.87 g/L·h, respectively). Not only glucose, BC-001 could utilize several carbon substrates for lactic acid including arabinose, xylose, sucrose, and fructose. From the preliminary data obtained in first screening test, we proposed this study to optimize the process conditions to achieve a high production performance of L-lactate fermentation by this novel strain. The results in the flask culture revealed that a proper seed culture was obtained at the correct physiological stage with adequate mixing and sufficiently high air permeability. This resulted in the high production of lactic acid. Further optimization was conducted in a 5-L stirred fermentor employing the high/heavy-inoculum concepts. It was found that the high-inoculum (71% inoculum size) was significant increase in lactate productivity (5.5-6.1 g/L·h). Interestingly, BC-001 could use both calcium bases and monovalent based for pH control during lactate fermentation in the 5-L stirred fermentor. This indicated that the fermentation process was easy to control and operate. To confirm BC-001 performance as the industrial L-lactate producer, the fermentation platform was conducted in 3 series of the 30, 300, and 3,000 L stirred fermentor. To control the phenomena of lactate production performance in scale-up fermentor, the power input per unit volume was selected as the constant criterion. From the pilot scale test, we obtained the fermentation reproducibility in the 3 series of the fermentation runs.