Peptone production from marine and culture wastes by commercial enzymes for bacterial culture media

Thirty to 40% of total fish catch is converted to waste. Using different methods of hydrolysis of the protein can be recovered of fish waste and increase the amount of protein efficiency. In this study, the four enzymes Alcalase , protamex , pepsin and trypsin were used for hydrolysis of four fish species including common carp (Cyprinus carpio) , silver carp (Hypophthalmichthys molitrix) , grass carp (Ctenopharyngodon idella) and the Big head (Hypophthalmichthys nobilis). The effects of pH, temperature and hydrolysis time on the rate of hydrolysis were studied on soluble proteins and degree of hydrolysis (phase I ). In the second step, proximate factors of peptone been evaluated and eventually replace commercial peptone media MRS ( Lactobacillus plantarum , Lactobacillus delberuki , Lactobacillus casei , Streptococcus thermophilus ) and TSB ( Listeria monocytogenes, two species of Bacillus and Pseudomonas, Streptococcus faecium) and the optical density of bacteria at different times were compared with control samples . Results showed that the highest degree of hydrolysis and soluble proteins were referred to alcalase and protamex, pepsin and trypsin respectively. The highest value of hydrolysis, in all treatments, was attributed to grass carp and silver carp, common carp and big head respectively. The best pH and temperature for alcalase, protamex, pepsin and trypsin 8.5and 55, 7.5 and 55, 3.5, 37, 7 and 37 respectively. Best time to achieve the highest degree of hydrolysis and soluble protein was 90 minutes. Qualitative analysis showed that the highest and lowest amounts of protein and fat in the treatment of alcalase (about 70 % protein and less than 0.5 % fat ) and protamex, pepsin and trypsin was then . The results of bacteria culture showed that the highest percentage growth of lactic acid bacteria was referred to Streptococcus thermophilus and Lactobacillus casei had the lowest rate of growth. In other bacteria, Pseudomonas and Bacillus species were the highest percentage of growth and Listeria monocytogenes and Streptococcus faecium respectively. In all treatments, alcalase had the best results and the peptone prepared from fish waste grass carp had the best condition for growth of used bacteria. It seems that the initial substrate , the parameters used such as temperature, pH, and enzyme hydrolysis time , have a significant effect on the quality of peptone and protein content in the final product is determined value of protein for culture of bacteria.

Iranian Fisheries Science Research Institute

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