Nucleases of some udder pathogenic organisms. In vivo and in vitro production.

The nuclease activity in quarter milk samples from cows with mastitis, and in vitro nuclease production by some udder pathogenic microorganisms were tested. Results concerning Staphylococcus aureus are, however, dealt with in a separate paper. Streptococcus dysgalactiae was found to be a vigorous and frequent producer of nuclease both in vivo and in vitro. The production by S. agalactiae was quantitatively inferior to that by S. dysgalactiae. Nearly half of the S. epidermidis strains were found to excrete a nuclease, and this enzyme was also demonstrated in the milk of cows with S. epidermidis mastitis. Comparatively high nuclease activity was recorded in the udder secretions of some cows with summer mastitis. All the tested strains of Gorynebacterium pyogenes were nuclease positive when tested by agar plate methods.