Acceleration of Vitamin E Deficiency by Torula Yeast. II. Effect of Torula Yeast Ash and Lipid

Abstract

In previous publications from this laboratory it was shown that addition of 7.5-307C of Torziln yeast to purified diets which were free of vit. E and selenium caused an increase in incidence and in rate of development of exudative diathesis in chicks( 1.2). Part of the anti-vit. E property of Tortrln yeast was found to be due to the inorganic fraction. whereas no effect was apparent with the lipid from the yeast. Subsequently. Dam ct a1. (3) reported that samples of Tortila yeast contained considerably more lipid than we had found, and they postulated that the unsaturated nature of the lipid could account for the anti-vit. E effect of the yeast. It is here shown that both the inorganic and lipid fractions of Torulu yeast have anti-vit. E effects. and further. that a combination of the lipid and the ash of Torulrr yeast will duplicate the exudate-promoting properties of the whole yeast. The relatively high unsaturated fat content of the yeast reported by Dam cf ul.( 3 ) is confirmed.Feed grade Torula yeast" was used in all studies. Ashes of the yeast were prepared by incineration in a muffle furnace at 250°C for 2-3 hours, then at 550°C: overnight. Average yield was 7%. Khen a fisative was used. magnesium carbonate equal to 8% of the weight of yeast was first mixed with the yeast. For isolation of the lipid from Torula yeast, 1200 g of yeast were mixed with 1200 ml of 95% ethanol and 6 1 of 6N HCI. After refluxing for 1% hours the mixture was cooled, 3 1 of ethanol added. and extracted in batches with a 1:l mixture of benzenepetroleum ether. The solvent was evaporated in vacuo and the dark brown oil dissolved in ethanol to facilitate mixing in the diets. To characterize the lipid fractions of yeast. 25 g samples of yeast were extracted with chloroform in a soxhlet apparatus. The materialMethods.-_.. *Feed grade lN, Lake Stgtes Yeast Corp. -obtained was labelled "free lipid". The extracted yeast was then refluxed for 2 hours with 5 r\; h'aOH,t cooled, neutralized with HCl and extracted successively with petroleum ether, diethyl ether and benzene. The combined extracts were washed with water, dried over Xa2S04 and evaporated to dryness in ZYZCUO. The residue was dissolved in hexane, filtered and the solvent removed. This material was called "bound lipid." The fatty acids from the free and bound lipids were obtained after saponification and analyzed for polyunsaturation by a modification of the alkali conjugation method of Wiese and Hansen(4). In the nutritional studies, day old Sew Hampshire chicks, 8 per group, were fed diet C47A(2) but with an additional 0.2% DL-methionine. This diet, designated C47B, contained in % : soybean protein$ 28, cerelose 61, vit. E-free lard6 4, salts A 6, DL-methionine 0.8, and vitamin mix 0.2. Additions to this diet, were a t the expense of cerelose. The chicks were housed in electrically heated batteries and permitted food and water ad libitum After the 14th day, they were inspected daily for symptoms of exudative diathesis. Experimental periods were 28 days. In evaluating the symptom...