FRUCTOOLIGOSACCHARIDE UTILIZATION BY SALMONELLAE AND POTENTIAL DIRECT-FED-MICROBIAL BACTERIA FOR POULTRY

Experiments were done to characterize potential direct-fed-microbial ( DFM) bacteria for poultry and Salmonella spp. with respect to their ab ilities to metabolize fructooligosaccharide substrates (FOS-50(R) or p ure FOS). Oxygen uptake (QO(2)) by these bacteria in media containing either glucose, FOS-50(R), or FOS was determined with a Warburg respir ometer. QO(2) values for Salmonella spp. in media containing glucose o r FOS-50(R) were similar(P > 0.05); however, QO(2) values in medium wi th FOS were significantly lower (P < 0.05). The QO(2) values for Enter ococcus faecium, Lactococcus lactis, and Pediococcus sp. were consider ably lower, reflecting the inability of these bacteria to oxidatively utilize these carbohydrates. The ability of E. faecium, L. lactis, and Pediococcus sp. to ferment glucose, FOS-50(R), or FOS was determined by measuring pH changes of the media. All carbohydrate sources were fe rmented by these bacteria, but at different rates. The lowest pH value s (<4.6) were obtained in inoculated media supplemented with glucose. The highest fermentation rate was achieved by Pediococcus sp. (pH < 5. 2 at 7 h), while L. lactis showed the slowest fermentation rate (pH > 6.4 at 10 h). To test the ability of Pediococcus sp. to hydrolyze FOS substrates, a cell-free extract was spectrophotometrically analyzed fo r the presence of active enzymes capable of hydrolyzing FOS or sucrose (a component of FOS). Hydrolysis of FOS (release of glucose) but not of sucrose was evident. However, equal activity was found in aqueous F OS without the cell-free extract, which suggests that free glucose was a component of the FOS solution tested.