Mathematical modelling on the growth of thermophilic lactic acid bacteria in molasses

• Main Author: Thian, Sing Kit
• Format: Final Year Project Report
• Language: English; English
• Published: Universiti Malaysia Sarawak, (UNIMAS) 2015
• Subjects: Q Science (General)
• Online Access: http://ir.unimas.my/id/eprint/10660/1/Mathematical%20Modelling%20On%20The%20Growth%20of%20Thermophilic%20Lactic%20Acid%20Bacteria%20In%20Molasses%20%2824pgs%29.pdf; http://ir.unimas.my/id/eprint/10660/8/Thian%20Sing%20Kit.pdf; http://ir.unimas.my/id/eprint/10660/

A recently isolated lactic acid bacteria (LAB) from the Biochemistry Laboratory of UNIMAS that is capable to produce lactic acid (LA) from carbon source by fermentation under high temperature was studied. The strain was used for LA production from molasses at 20 g/l, 40 g/l and 60 g/l substrate concentration under controlled pH at 6.0 and temperature at 45 °C. Molasses is an abundant and low-cost bio-resources from the sugar mill industry and contain fermentable sugars. In this study, a mathematical model was generated to describe the batch fermentation of molasses to LA with the LAB strain, with the bacterial density, LA production and residual sugar as responses. The Monod equation was applied to describe the bacterial growth, while the Luedeking-Piret equation was employed to describe the production of LA. The fermentations produced a maximum specific growth rate, μmax of 0.381 h-1 and substrate saturation constant of 13.81 g/l. The model depicted that the production of LA from molasses medium was related to the rate of bacterial growth and the quantity of bacteria present. The model could be used to study and optimize the growth and production of lactic acid using the LAB in molasses medium fermentation system.