The antimicrobial activity of metabolites produced by Lactobacillus acidophilusNA-5 was tested in vitro against some food pathogenic microorganisms; it was determined by agar well diffusion method. Bacillus cereus, Sallmonella typhimurium no.22 and Candida albicans were selectedfrom seven food borne pathogens for their sensitivity towards L. acidophilusNA-5 metabolites when grown in Man Regosa Sharpe media (MRS). Lactobacillus acidophilusNA-5 was grown in different dilution of the selected waste material (cheese whey) as the sole carbon source to determine the concentration required for the induction of highest antimicrobial activity against the tested pathogenic organisms. The different dilutions of cheese whey suggested were (25:75, 50:50,75:25 and the original cheese whey). As well as the original cheese whey which showed the most inhibitory effect against the selected pathogens.
             Further experiments were done to optimize the cheese whey media, by adding different concentrations of nutritional elements. pH and temperature were also tested for optimization.   Results revealed that 1% peptone, 0.4% beef extract, 0.6% yeast extract and 0.5% sorbitol were the optimum concentrations which showed highest activities against the growth of selected pathogens.
            The optimum pH and temperature showed that the most antimicrobial activity were at 6.2 and 37^°C, respectively. From the results obtained, the formulated cheese whey waste material might be used as a less expensive culture media for the production of beneficial metabolites by L. acidophilusNA-5 with remarkable antimicrobial activities.