Degradation of dietary fibre from ‘Gari' by faecal bacteria and bacteria extracellular polysaccharidases

Abstract

Dietary fibre (soluble and insoluble fibre) was extracted from ‘gari' (a fermented cassava product). The ‘gari' fibre was subjected to degradation by faecal microflora and the
microbial extracellular enzymes obtained from six clinically healthy adults (S1-S6). Other common components of dietary fibre namely starch, xylan, carboxymethlcellulose (CMC) and polygalacturonic acid (PGA) were also treated with the extracellular enzymes.
Degradation of the fibre was monitored by measuring the reducing sugar groups in the reaction mixture. Enzyme activity was expressed as units/mg protein. The results
obtained demonstrated that the human faecal microflora were able to degrade the gari fibre considerably within 24 hr of incubation. The values obtained for the reducing
sugars ranged from 1.5-4.5 mg/ml. Degradation rate varied considerably between the six individuals. Effect of the faecal extracellular enzyme on the fibre indicated a high
concentration of the starch hydrolyzing enzyme, amylase. For all the six subjects the activities were (U/mg protein): amylase 2.5-5.4; xylanase 0.8-3.6 and pectinase 0.088-
2.1. Cellulases activity detected in only one of the subjects was 0.76 U/mg protein. The results of this study suggested that the fibre from gari may be rich in starch component
resistant to the action of amylase and amyloglucosidase and this component were readily degraded by enzyme from the faecal microflora.

Keywords: Dietary fibre, gari, faecal bacteria, extracellular polysacharidases.

Nigerian Food Journal Vol. 25 (1) 2007: pp. 46-55