573 The aim of the present work was to study the precipitation of various peptides and proteins with sulphite spent liquor and wi,th isolated lignosulphonic acids. MATERIALS AND METHODS Sulphite spent liquor. A fermented liquor from an alcohol distillery was used. The analytical data of the liquor were as follows: Dry basis 8.5 % ; sugars 1.5 % and pH 5.1. This liquor is referred to as Clf'IUde sulphite spent liquor. Dialysed liquor was also used with dialysis being carried out against running

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... ap water for 15 hrs. The liquors were stored at -20 ° C. Lignosulphonic acids. Sulphite spenrt liquor was treated with CaO (1.5 g CaO per 100 ml of sulphite spent liquor) at 40°C. The p,recipitaite was centrifuged and washed twice with distilled water, after which the upper homogenous layer of the centrifuged precipitate was collected, dissolved in 0.01 M-HCl, and 0.1 M-NaOH added to pH 6.8. The solution was dialysed against running tap waiter for 15 hrs. in order to remove low molecular weight saccharinic acids and saccharates, and small free cations and anions according to the precipitation theory of Hall (1956). Low molecular weight lignosulphonic acids are also supposed to be lost during dialysis. Only traces of oxalic acid-precipitable substances could be identified after dialysis. The purified material was freeze-dried and stored in a desiccator at room temperature, and solutions to be used prepared when needed. These lignosulphonic acids are referred to as isolated lignosulphonic acids. Agar gel. For experiments performed on agar plates 1.15 % Bacto ... agar (Difeo* 0140-01) was used as basis. Thimerosal was added (final concentration 0.01 % ) as microbicidal agent. The addition of thimerosal was found to have no influence on the experiments carried out on the agar plates. Preparation of peptide-and protein-agar plates.