In this work, the collagen hydrolysates with different molecular weights were successfully extracted from the limed hide waste, and used at the nutrient solutions for crop breeding. Firstly, using the single factor and orthogonal exp eriments, hydrolytic process parameters of limed hide waste were optimized for the Alcalase-based enzymatic and Ca(OH)2-based alkali, and alkali-enzyme methods that led to the corresponding collagen hydrolysates with different molecular weights. The obtained collagen hydrolysates were characterized by gel permeation chromatography (GPC), amino acid analysis, the inductively coupled plasma optical emission spectrometer (ICP-OES), and Kjeldahl method. Then, the collagen hydrolysates were used as organic nitrogen sources to prepare fertilizers for the grow seedlings of Triticum aestivum, Glycine max, and Brassica napus, and inorganic nitrogen solutions were used as controls. The effects of these nutrient solutions on the seedlings and growth of the three crops were investigated. Concretely, the germination rate, plant weight, seeding height, soluble sugar content, and chlorophyll content were tested. Results indicated that all the collagen hydrolysate products could be used to prepare water-soluble fertilizers that can intensively boost germination, plant weight, and seeding height, and greatly increase soluble sugar and chlorophyll content in leaves. Furthermore, the fertilizer efficiencies of all the tested degradation products are much better than that of the water-soluble fertilizer containing inorganic nitrogen. All the proteolytic nutrient solutions with different molecular weights can promote the growth of crops, but the smaller the molecular weight is, the better the growth effect of crops is, which is manifested in the higher germination rate, plant weight, seedling height, soluble sugar content and chlorophyll content of seeds.

Li Zhao, Yanru Long and Haibin Gu