Farmed salmon rest raw materials as a source of peptones for industrial fermentation media

Twelve marine peptones prepared from rest raw materials (RRM) from farmed salmon have been evaluated as nutrient sources in growth media for industrial microorganisms. The peptones were prepared from head and backbones, or from head, backbones and viscera, using different proteases and one or two-step hydrolysis. Growth was determined as optical density using a high-throughput robotic system, allowing for testing of a large number of peptones and microorganisms. For two Lactobacillus-strains tested, the peptones were the only nitrogen source, while for four aerobic bacteria and yeasts, the peptones were assessed as a source of growth factors, with inorganic nitrogen in excess in the media. The peptones containing viscera resulted in higher cell yields than those without, and high growth rates were maintained to higher cell densities. The viscera-containing peptones were better than meat-based peptones, and equally good as yeast extract. The differences between the performance of peptones with and without viscera could be explained by the mineral content and the degree of hydrolysis. Since peptones based on farmed salmon RRM can be provided in large quantities with a stable quality, they should be further explored as a nutrient source for the fermentation industry.