Optimization of production medium for high cell mass production and the functional characteristics study of bifidobacterium longum WICC B34

Abstract

Bii¬dobacteria are used as probiotic mainly in the dairy industry as cell suspensions or as freeze-dried additives. Bifidobacterium longum is important in maintaining our general health and considered as a probiotic as they contribute in desirable changes and produces protective effect in the intestinal tract. Furthermore, Bifidobacteria also important in the prevention and treatment of diarrhoea by participating in competitive exclusion against diarrheagenic bacteria. Anaerobic growth of B. longum and its organic acids by product give some restriction to their growth. Therefore, the goal of this research is to select suitable production medium for B. longum and its growth characteristics on this medium. Several media were tested for the potential effect to the cell growth. The best medium with glucose as the carbon source gave the cell mass of 2.58 g L-1. In shake flasks cultivation, further optimization by using classical method (OFAT) gave the cell mass of 6.03 g L-1 which was increased up to 130.37 % when compared with growth in un-optimized medium. Despite of medium optimization study, there are some others important factors such as acidity, bile, hydrophobicity, antimicrobial sensitivity, and antibiotics susceptibility which can affect B. longum to remain and exert their potential functionalities in a host. Study on its growth characteristics revealed that B. longum has good resistance to bile salt concentration with 79 % cell survival at concentration of bile salts about 0.3 %. However, the resistance to bile salt was found to be affected by pH value. Following two-hour treatment, no cells survived at pH 1.0 while about 41.7 % of cells survived at pH 4. Surface adherence of the cells was tested by using hydrophobicity assays. High degree of hydrophobicity was observed during exposure to chloroform which gave the value of 86.1 %. Susceptibility of the cells was also tested with antimicrobial and antibiotics. B. longum was found resistant to the entire pathogenic microorganism tested and susceptible to rifampicin, gentamycin, erythromycin, and ampicillin.