Growth Requirements of Schizosaccharomyces octosporus, a Yeast Exacting towards Adenine

Abstract

The growth requirements of a strain of Schizosaccharomyces octosporus were studied by auxanographic and tube tests. The organism grows satisfactorily on a glucose + mineral salts medium containing asparagine and ammonium sulphate, provided also that inositol, pantothenic acid, nicotinic acid, biotin, histidine, methionine and adenine are added. Coniplex interactions between adenine and guanine were found, and for this reason 8. octosporus cannot be regarded as a suitable test organism for the assay of adenine.The present investigation arose from studies still in progress of the. inositol requirements of a number of yeasts. Twelve strains were examined, and growth of eleven of them was satisfactory when inositol or yeast extract was added to a defined medium containing glucose + mineral salts, ammonium sulphate, casein hydrolysate and B vitamins. The exception was S . octosporus which failed to grow in absence or presence of inositol. Further investigations showed that S . octosporus required adenine, not hitherto reported as an essential metabolite for yeasts, and its growth requirements were therefore studied in more detail. METHODSTube tests. The usual procedure for microbiological assay was followed, but in place of bacteriological tubes, flat-bottomed tubes (Samco), 4 x 9 in., were used.Tubes were selected so that the internal diameter was within the limits 1-66 and 1-72 cm. The tubes, containing 6 ml. of test medium and covered with loosely fitting glass caps, were sterilized for 10 min. a t 10 lb. pressure. After inoculation, they were incubated in a vertical position at 25" in a water-bath.Estimation of amount of yeast growth. The tubes were fitted into a black wooden container open a t opposite sides which held them in the optical beam of the Spekker absorptiometer, in the place normally occupied by the glass cells. Thus turbidity readings could be taken from the same tube a t intervals during the growth of the organism, without exposing the contents to contamination.Test organism and inoculum. The test organism, carried on malt agar slopes, was subcultured weekly or more frequently as required. In the preparation of the inoculum a loopful of a 24 hr. culture was suspended in 6 ml. of basal medium to give a turbidity in the tubes reading between 0-15 and 0.25 in the Spekker (i.e. approximately 0.2-0-4 mg. dry weight yeast/6 ml.

Excretion of Nicotinic Acid by Biotin-Deficient Saccharomyces cerevisiae

“…Cultures (6 ml.) of the yeast were grown in Samco tubes as described by Northam & Norris (1951). When large volumes of culture filtrate were required, 100 ml.…”

On the Clumping of Corynebacterium xerosis as Affected by Temperature

“…cultures were grown in Samco tubes covered with anodized aluminium caps (0x0 Ltd., Queen Street Place, London, E.C. 4; Northam & Norris, 1951). Inocula were prepared by suspending sufficient organisms from a 24-hr slope culture in 6 ml.…”

A Microbiological Assay of Inositol: its Development and Statistical Analysis

“…Of the methods of fractionation attempted (Northam, 1951) the following was found to be satisfactory:…”

“…The modified basal medium, BM I + CH, corresponds to ' Basal medium I11 ' described by Northam & Norris (1951) with the exceptions that the lactate buffer was adjusted to pH 4.8 and the concentration of the casein hydrolysate was diminished by one half.…”

“…Estimation of amount of yeast growth ( a ) When studying growth rate: the turbidity of the yeast suspension was measured by fitting the tubes into a wooden container placed in the optical beam of the Spekker absorptiometer (Northam & Norris, 1951).…”