SummaryMethods for reducing the content of nucleic acid in protein concentrates from disintegrated yeast and microalgae were investigated. Protein concentrates were prepared by acid precipitation of extracted protein after cell wall separation. The influence of alkaline protein extraction on the content of RNA in isoelectrically precipitated protein concentrates was studied. I t was found that when a strong decrease in the RNA content was obtained, this was followed by a decrease in the yield of protein concentrate. Protein concentrates were also prepared without cell wall separation by precipitation with different agents after cell disintegration. In the precipitates from microalgae, a RNA reduction was obtained. Precipitation of yeast protein gave no essential reduction with the precipitants used. Precipitation of yeast protein by heating at an alkaline pH gave a protein concentrate with a low content of RNA. A slightly lower RNA content was obtained when the precipitation was performed in the presence of NaC1. The yield of amino acid nitrogen was 70-80% and the RNA content was l-2yO. A process with precipitation a t alkaline pH for the production of microbial protein concentrates with a low content of nucleic acid is suggested.
Single cell protein (SCP) intended for animal feed purposes was produced in a pilot plant. The SCP consisted of Methylomonas methanolica, a pseudomonas species which is an obligate methanol user. The SCP was cultured in fermenters and later dewatered and dried in a spray-drier. Seven of eight research workers had febrile reactions 6-12 hours after exposure to SCP dust. All workers had high titres of IgG and IgM antibodies against the pseudomonas species as measured with indirect ELISA and passive haemagglutination techniques. The mechanism behind the febrile reaction is judged to be a non-immunological reaction caused by endotoxins. By increasing the particle size of the SCP through using different drying procedures, a product which generated less dust was obtained.
Norprotein is a subsidiary of the Norwegian chemical group Norsk Hydro A.S and the Swedish food company AB Marabou. Since 1914 the main activity of research has been to develop a process for single-cell protein production from methanol. At present, research activities are directed towards finding alternative applications for the developed technology within the field of biotechnology.
14.Anon. Milling Feed and Fertiliser 1979, CLXII (9, 16.
Norprotein is a subsidiary of the Norwegian chemical group Norsk Hydro A.S and the Swedish food company AB Marabou. Since 1914 the main activity of research has been to develop a process for single-cell protein production from methanol. At present, research activities are directed towards finding alternative applications for the developed technology within the field of biotechnology.
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