Kluyveromyces osmophilus, a new yeast species
In 1962 Dr. R. ANTOINE of Mauritius sent a number of yeast strains isolated from sugar for identification to the Yeast Division of the Centraalbureau voor Schimmelcultures at Delft. One of these strains is considered to belong to a new species for which the name Kluyverornyces osmophilus is proposed. It will be described in the following part. This yeast strain was conspicuous by forming oval to reniform spores which were easily liberated from the ascus. When first studied, sporulation was abundant. The picture of the spores in this paper. (fig 2) is an electron micrograph of ultra-thin sections of a preparation fixed at that time with osmic acid and uranyl acetate according to RYTER et al. (1958). Unfortunately, the sporulating ability has been lost after maintaining the yeast for two years on malt agar. The yeast, grown on malt agar, was investigated according to the methods of WICKERHAM (1951) and of LODDER & KREGERVAN RIJ (1952). As regards the fermentation and assimilation reactions some remarks can be made. Fermentation of a 2% (w/v) glucose solution in a Durham tube was rather slow, i.e. the insert tube was filled up with gas after 10--14 days' incubation at 25 ° C. A 10% glucose solution gave the same result after 5--7 days, while a 30% glucose solution had a gas-filled insert tube after 5 days. Apparently, in solutions with a higher sugar concentration the fermentation rate was high at an earlier period. The assimilation test with the auxanographic method gave positive results for glucose and galactose only. The assimilation test in a synthetic liquid medium with glucose as the sole source of carbon in a concentration of 0 .50, read after one week at 25 ° C, show-
A SIMPLE TECHNIQUE FOR OBTAINING MATING TYPES IN HETEROTHALLIC DIPLOID YEASTS, WITH SPECIAL REFERENCE TO THEIR USES IN THE GENUS HANSENULA
A procedure has been devised by which large numbers of ascospore isolates may be obtained from yeasts without the use of a micromanipulator and auxiliary costly laboratory equipment or a need for the exacting skills which such tools require. The procedure is being continually applied in this laboratory to the genus Hansenula. Some of the species of this genus produce many ascospores, but so few are viable that isolation of mating types by micromanipulator is often impractical. Hence for genetical studies different experimental procedures are required. In this genus the ascus ruptures when it is mature and the liberated ascospores often agglutinate in large masses. This habit of early escapement from the asci also tends to thwart the usual tetrad analysis that starts with isolation of the four ascospores by micromanipulation. It is intended that the new procedure for isolating mating types and simple ancillary techniques for genetical analyses will be modified to whatever extent is necessary so that they may be applied to a genus like Saccharomyces where viability of ascospores is usually high and the ascus usually remains intact until the ascospores germinate. Various uses of the new procedure will be presented with examples taken from results obtained for the most part with diploid species of Hansenula. The principal procedure for the isolation of cultures derived from single ascospores is based on the fact that ascospores can withstand slightly more heat than vegetative cells. For most species of Hansenula, 57 or 58 C is employed.
The chromosomes of Chrysanthemum,
NEW varieties of the garden chrysanthemum arise primarily from seed. They are propagated vegetatively and many give rise to bud sports in sequence and in parallel to give whole families of varieties. The original sports would naturally be chimras and it is not surprising therefore that they often revert to the previous type. Whereas some varieties sport continually from the time of their origin, others remain stable for many years. Those considered in this account do, mostly, sport freely. Since varieties may remain stable for a considerable number of years and then suddenly sport it is probable that all varieties possess the ability to sport. The origin of bud sports is unpredictable. Some confusion in naming has arisen as the same or similar sports have occurred and been propagated in different places under different names. Consequently there are, for example, several forms similar to, but not identical with, the original Favourite Supreme raised by Messrs A. G. Vinten. It might well be that each individual variety would be better termed a sub-family to include all its minor variants. The different Chrysanthemum sports are described in scattered numbers of the R.H.S. Journal—more particularly, for the Favourite family, in Vol. 63, 1938, pp. 139-141. The object of this study is to discover the cause of sporting.