Differentiation of food spoilage bacteria on the basis of their ability to utilize different proteins
1979
Sikes, A. | Maxcy, R.B.
Since spoilage bacteria produce proteolytic enzymes which act on food proteins reducing safety and quality, analytical methods must be developed which differentiate bacterial proteases of different specificity, in terms of their ability to use different protein substrates. Proteolytic activity of 122 bacterial isolates from chicken was examined in 4 unfractionated proteins (egg albumin, gelatin, casein, and beef muscle) and 3 casein fractions. Three distinct groups of proteolytic bacteria were identified: one group completely hydrolyzed all test proteins; the second group exhibited selective hydrolysis; the third group was unable to hydrolyze test proteins to produce amino acids needed for growth. Spoilage isolates unable to hydrolyze one test protein often hydrolyzed others, and showed no preference for either native or denatured proteins. These data suggest that use of a single protein substrate to screen for proteolytic activity is unwise; plating methods need to be developed to distinguish proteolytic bacteria present in foods.
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