Chemical properties of Mannan Containing Polysaccharides from palm kernel meal and its inhibitory effect againts salmonella spp and e. coli

Abstract

Mannan linkages can not be degraded by monogastric animals. Mannans, however, were proved to he useful in inhibiting the multiplication of pathogenic bacteria in the digestive tract of animals. The aim of this study was to investigate the chemical properties of mannan containing polysaccharides from palm kernel meal (PKM) and their in vitro inhibitory effect against Salmonella spp and E. coli. The combination of chemical, physical and mechanical treatments was used to extract the cell wall of PKM. The extraction product was then autoclaved at 121° C for 15 minutes and centrifuged at 16 000 g for 15 minutes. The supernatant was separated chromatographic ally using gel sephadex (i-50 (3 x 80 cm) in order to separate the carbohydrate fraction from protein. The carbohydrate fraction was evaporated and evaluated for its chemical and physical properties. An agglutination test was done by adding a suspension of 1 ml bacteria to 1 ml of mannan containing polysaccharides. The inhibitory effect of mannans on bacteria was tested by incubating bacteria in liquid media containing 0, 1000, 2000, 3000 and 4000 ppm mannan containing polysaccharides in terms of total sugar. The extraction results showed that 669,72 mg mannan containing polysaccharides could be isolated from 100 g PKM. The polysaccharides had brown colour, sugar flavour, were soluble in water and consisted of glucose, man nose and galactose in a ratio of 8:20:1. The addition of mannan containing polysaccharides to the bacterial test did not show a visual agglutination effect but there was an indication that the bacteria clustering was cfl'ected by mannan containing polysaccharides. The total number of Salmonella spp and E.coli in vitro decreased as the concentration of mannan containing polysaccharides in the media increased. From the results of these experiments it can be concluded that the polysaccharide fraction in PKM is dominated by mannans. There is an indication that these mannans are able to inhibit Salmonella spp and E. coli in vitro.