Browsing by Author "Ching, Wan Lih Jr"

Bifidobacteria confer various health benefits to the host. Bifidobacterial growth can be promoted by caseinomacropeptide (CMP), which is the potential oligosaccharides-bearing portion of the κ-casein (κ-CN) in milk. This project was carried out to study the utilization of bovine glycosylated CMP by Bifidobacterium infantis ATCC 15697, B. bifidum ATCC 29521, and B. longum ATCC 15707 as well as to investigate the growth-promoting effect of CMP on these strains. Two types of media, namely the basal chemically-defined medium (bCDM) and the nutrient-rich medium known as de Man-Rogosa-Sharpe (MRS), were employed to achieve respective research objectives. The formula of the bCDM was developed by addition technique. It was found that L-cysteine, magnesium and manganese were needed by all the strains, and additionally, thiamin and nicotinic acid were essential for the growth of B. bifidum ATCC 29521. Since more than 70% of the glycosylated chains attached to a CMP are terminated with sialic acid residues, the cell counts and bound sialic acid contents in the media after incubation were analysed. Higher cell counts and lower bound sialic acid contents were found in the inoculated media supplemented with CMP as compared to unsupplemented group. Unexpectedly, slower microbial death, instead of growth, was observed in all inoculated bCDM+CMP in comparison to bCDM. It was also surprising to discover that B. bifidum ATCC 29521 and B. longum ATCC 15707 can utilize the glycosylated chains despite that no sialidase has ever been isolated from them. As a conclusion, B. infantis ATCC 15697 can cleave and utilize sialic acids, but not other glycans, that are attached to the glycosylated CMPs; while both B. bifidum ATCC 29521 and B. longum ATCC 15707 can cleave terminal sialic acid residues, followed by the utilization of the glycans attached to the glycosylated CMPs other than sialic acids. It was also found that bovine CMP can exert a similar growth-promoting effect on all three strains. From an industrial point of view, it is feasible to add the bovine CMP into the bifidobacterial growth medium to enhance their growth. Further study is warranted to characterize the sialidases present in B. bifidum ATCC 29521 and B. longum ATCC 15707.