The effect of adding alkaline hydrolysate of sheep's wool waste on the chemical and microbiological properties of a park soil (Sofia, Bulgaria) has been assessed in a 9 month laboratory experiment. The waste product contained 75-80% water-soluble materials: peptides, amino acids, salts, dyes, lipids, some carbohydrates, potassium ions, and it seemed likely that the hydrolysate obtained could be used as a harmless and valuable fertilizer in agriculture. It was demonstrated that the organic material positively influenced microbial soil populations and ryegrass growth. As the remaining partially degraded keratin is highly dispersed it should act as a slow release fertilizer thus feeding plants additionally. The results suggest that the wool hydrolysate is beneficial for improving soil characteristics and could successfully be used as alternative biofertilizer. The authors hope that by utilization of the keratin wastes, the environment around leather and fur plants could be influenced positively and that the expense of removing the wastes to controlled landfill sites and part of the expenses for sustaining the latter will be saved.

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.

Suitable conditions were found for hydrolysis of sheep wool by a mixture of potassium hydroxide and some quantities of sodium hydroxide at elevated temperature (120" C) and pressure (2.03 atm). Because of the severe hydrolysis conditions (pH about 12 and high temperature) it is believed that the causes of some related diseases like "mad cow", "swine fever", bovine spongiform encephalopaty, Creutzfeldt-Jakob disease, that are called prions, and are proteins will be destroyed. The hydrolysate obtained is neutralized by orto-phosphoric acid. Beside organic nitrogen, the obtained hydrolysate contains also potassium and phosphate ions and threfore it is proposed this product to be used as fertilizer in the agriculture. Data are supplied showing the positive effect on rye-grass when the soil was additionally enriched with the new fertilizer. The alkaline hydrolysate contains about 75-80% watersoluble materials-peptides, amino acids, salts, dyes, lipids and some carbohydrates. The remaining part consists of insoluble partly degraded keratin. The latter ·is highly dispersed and therefore it is believed that it will be degraded by the soil microorganisms for relatively short time, thus feeding the plants additionally.The authors hope that if this way of utilization of the keratin wastes is used the environment around the leather and fur plants will be influenced positively and that the expenses for carrying away the wastes to controlled dung-hills and part of the expenses for sustaining the latter will be safed.

A biotechnological procedure based on alkaline hydrolysis has been developed for effective processing of various types industrial animal wastes to convert them into a low cost high value biodegradable end product. It was demonstrated in laboratory scale experiments that the bioproduct obtained positively influenced microbial soil populations and ryegrass growth in both soils used, park soil and mine spoils. As the remaining partially degraded waste residue is highly dispersed it should act as a slow release fertilizer, thus feeding plants additionally. Therefore, the protein hydrolysate obtained is suitable for application as a harmless and valuable biofertilizer. The proposed method for solubilization of proteinaceous wastes is simple and economically viable making its implementation easier on an industrial scale. Therefore, the method could be of great help to the enterprises of the meat industry, avoiding using landfills and incineration.

A perspective approach is proposed in which ground chicken bones remaining in the poultry slaughterhouses after extracting the meat from them for human food are treated by minimal amounts of purified alkaline protease (Alcalase). Using this process two principal fractions were obtained-soluble protein hydrolysate (SPH) that can be used as component of microbiological cultivation broth media or as a "protein" nutritive additive in the diet of domestic animals and insoluble mainly inorganic fraction (IF) that can find application as fertilizer containing Ca, Mg, and small amounts of P, C, and N or can be used as additive in the diet of hens and other domestic animals. The yields of SPH and IF regarding the quantity of the starting chicken bones were about 22% and 18%, respectively. The process is perspective since: 1. It is energy saving especially when the SPH fraction is used directly for animal feeding without drying; 2. It is not labour consuming; and 3. A waste product is converted into useful substances without any pollution for the environment.