New protein hydrolysates from collagen wastes used as peptone for bacterial growth

A simple and low-cost procedure was developed for the effective processing of native calf skin and blood wastes to produce protein hydrolysates. The method includes extraction of high-molecular-weight protein from the raw material, followed by enzymatic hydrolysis of the extracted residue. The enzymatic hydrolysis was performed by inexpensive commercial subtilisin DY, produced by Bacillus subtilis strain DY possessing high specific activity. The contents of protein, nitrogen, ash, and amino acids of the obtained hydrolysates were determined and compared with those of the commonly used commercial casein hydrolysate (Fluka Biochemica, Switzerland). The newly obtained calf skin hydrolysate, called Eladin, was found to be suitable as a low-cost alternative peptone in growth media of different microorganisms, such as Escherichia coli, Pseudomonas aeruginosa, Salmonella dublin, and Staphylococcus aureus. The method allows utilization of waste materials by converting them into valuable protein products that could find widespread application in microbiologic practice.