DETECTION AND QUANTIFICATION OF POULTRY PROBIOTIC BACTERIA IN MIXED CULTURE USING MONOCLONAL-ANTIBODIES IN AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY

Murine monoclonal antibodies were used in an enzyme-linked immunosorbe nt assay (ELISA) for the detection and quantification of selected prob iotic bacteria present in a continuous-flow competitive exclusion cult ure known to be effective at reducing chicken cecal and crop colonizat ion by Salmonella typhimurium. Veillonella, Enterococcus avium and S. typhimurium were grown anaerobically in batch culture of Viande Levure broth in pure culture and mixed culture. The mixed cultures produced significantly more acetate and propionate than any of the pure culture s with acetate and propionate being the predominant volatile fatty aci ds. The association in mixed culture resulted in a significant increas e in cell numbers compared to the respective pure cultures. The ELISA was capable of detecting 10(4) cells per mi of the bacteria. The plots of cell numbers determined by the ELISA versus direct plating increas ed in accordance with increases in cell numbers with r(2) values of 0. 950, 0.922 and 0.940 for the pure culture incubations and 0.901, 0.924 and 0.905 in the mixed culture incubation for E. avium, S. typhimuriu m and Veillonella, respectively. The results indicate that the monoclo nal antibodies can be used to quantitatively assay individual probioti c bacterial species grown in a mixed culture incubation. (C) 1997 Else vier Science B.V.