Bioprocess development for anaerobic cultivation of probiotic bacteria bifidobacterium longum for high cell mass production

摘要

Bifidobacteria are used as probiotics mainly in the dairy industry as cell suspensions or as freeze-dried additives. Bifidobacterium longum (B. longum) are important in maintaining general health. The potential health benefits of B. longumto the human have led to their wide application in dairy products and food additives. Fastidious anaerobic growth of B. longum plus organic acids production as their byproductsgive some restriction in their growth as high cell mass become major concern. Therefore, the goal of this research is to select suitable medium as production media and optimization of the medium component for high cell mass production of B. longum by using one-factor-at-a-time (OFAT). Among nine growth media were evaluated to determine their suitability for high cell mass of B. longum, the best medium was yielded a cell mass of 4.5 g L-1 in shake study with the main components are glucose (20 g L-1), yeast extract (5 g L-1), meat extract (10 g L-1) and peptone (10 g L-1).Then, five different carbon sources which were glucose, lactose, sucrose, mannitol, and glycerol were screened in shake flasks and the best carbon source that contribute to the highest cell mass was glucose. Moreover, application of highly nutritious and costly nitrogen sources was incomplete application for industrial scale. Therefore, in this study peptone was found to be the best nitrogen source after screened with two others different nitrogen sources which were yeast extract and meat extract. Optimization by classical approaches achieving the maximum cell mass of 5.8 gL-1increased up to 28.88 % when compared with un-optimized media. Finally, batch cultivation was conducted in 16-L semi-scale bioreactor using the new formulated optimized medium under controlled and uncontrolled pH conditions at 37°C for 72 hours under anaerobic cultivation. It showed that under controlled pH, the maximal cell mass obtained in batch cultures was 13.8 gL-1 when compared with uncontrolled pH which only 6.8 gL-1with the percentage difference of 67.96 %. Thus the batch cultivation under controlled pH is the most suitable cultivation strategy for high cell mass production for industrialization of this bioprocess.