3.1. Isolation of Listeria spp and hemolytic activity
Of the total brewer's grains samples studied (n ¼ 32), Listeria spp. was isolated from one sample (3.12%) that corresponded to the November December 2010 sampling period. In Palcam agar, colonies were grayish-green with a browneblack surrounding halo caused by cleavage of esculin. The strain was identified as L. monocytogenes (LM1) after biochemical tests proposed by the Bergey's Manual of Determinative Bacteriology. L. monocytogenes isolated from brewer's grains showed values of hemolytic activity of 2 CHU and 8 MHU.