Chitosan oligosaccharides, dp 2-8, have prebiotic effect on the Bifidobacterium bifidium and Lactobacillus sp

In order to investigate the prebiotic potential of chitosan oligosaccharide (COS), prepared by enzymatic hydrolysis of fully deacetylated chitosan polymer, the effect of COS on bacterial growth was studied. The degree of polymerization (dp) of COS was determined by MALDI-ToF mass spectrometry, and the COS was found to be composed of dimer (33.6%), trimer (16.9%), tetramer (15.8%), pentamer (12.4%), hexamer (8.3%), heptamer (7.1%), and octamer (5.9%). The minimum inhibitory concentrations (MIC) of chitosan polymer against lactic acid bacteria and bifidobacteria were below 0.31%. However, this only applied to two strains, the other bacteria tested grew on MRS broth containing 5% COS. The effects of COS on the growth of bifidobacteria and lactic acid bacteria were compared with those of fructo-oligosaccharide (FOS). FOS was found to have a growth stimulatory effect on only three strains: Bifidobacterium bifidium, B. infantis and Lactobacillus casei. However, COS stimulated the growth of most Lactobacillus sp. and B. bifidium KCTC 3440. The amount of the growth and the specific growth rate of B. bifidium increased with increasing COS concentration. The cultivation time required to obtain maximum growth was reduced to about 25% in MRS broth supplemented with 0.2-0.4% COS. These results demonstrate that COS has considerable bifidogenic potential. Both cell growth and specific growth rates of L. brevis in MRS broth supplemented with 0.1% COS increased by 25%. The present study shows that COS stimulates the growth of some enteric bacteria, and that COS has potential use as a prebiotic health-food.