Morphological observations on Absidia corymbifera and Absidia blakesleeana strains preserved under mineral oil
Macro‐ and micromorphology of 30 living subcultures of Absidia corymbifera (10 strains plus three strains of Absidia ramosa) and Absidia blakesleeana (two strains) preserved under mineral oil at room temperature for periods ranging from 3 to 44 years in The Fungal Culture Collection of Instituto Oswaldo Cruz (IOC) were observed and described by permanent mycological preparations mounted in a glycerol 10% and/or Amann lactophenol solution. Vegetative and asexual reproductive structures are illustrated by drawings made with the aid of a camera‐lucida. The study showed that the period of maintenance under mineral oil and the stress which took place during the period of storage did not affect the vegetative and asexual reproductive morphology of the Absidia strains and species studied here.
THE INFLUENCE OF MINERAL OIL UPON THE OXYGEN CONSUMPTION OF SORDARIA FIMICOLA
THE APPLICATION of the mineral oil conservation method to maintaining large collections of fungous cultures has been described in the preceding paper (Buell and Weston, 1947). In connection with that study it seemed desirable to determine to what extent respiratory changes were brought about in the cultures under oil. We have been unable to find any reports dealing with respiratory studies of bacteria and fungi covered with oil. Several investigations have been reported on the viability of fungous cultures preserved over a period of time by means of paraffin or mineral oil (see Buell and Weston, 1947, for bibliography) and of bacterial cultures so treated (Morton and Pulaski, 1938; Rahn and Richardson, 1941). Studies have also been made of the diffusion of oxygen through mineral and vegetable oils of various densities (Sawaya, 1945) and through various bacterial media (Rahn and Richardson, 1941). Although not bearing directly upon the present problem, it should be noted that an interesting discussion of the breakdown and synthesis of oils by marine bacteria is presented in a recent book by Zobell (1946). In the present series of experiments we have applied a micro-respirometric technique to the study of the oxygen consumption of normal and oil-covered cultures of Sordaria fimicola (Rob.) Ces. and de Not. The data so obtained provide a physiological basis for the mineral oil conservation method. MATERIAL AND METHODS.-The fungus used in this study was a strain of Sordaria fimicola, an Ascomycete, originally obtained as one of the organisms isolated from a textile exposure test conducted in Panama. A modification of the method originally described by Hansen for isolation of pure yeast (Prescott and Dunn, 1940) was used under aseptic conditions to obtain the single spore isolations with which the stock cultures were inoculated. A dilute spore suspension of Sordaria fimicola was micropipetted onto the area of potato maltose agar which had been divided into minute squares with a razor. The spores germinated in about 4-6 hours. Shortly after germination occurred the slide was removed from the chamber and placed under the microscope. A square of agar with one spore was then selected, removed from the slide by means of a sterile needle and transferred to a slant of nutrient agar. The mature perithecia of the resulting colony were used as inocula for the experimental flasks. The flasks each contained 10 cc. of potato maltose agar and were incubated at 260C. following inoculation. The oxygen consumption was measured by means
PHYCOMYCES IN THE ASSAY OF THIAMINE IN AGAR.
Introduction In the course of experiments conducted by DAY (1), it was observed that an agar culture with a known quantity of thiamine produced a lesser dry weight of Phycomtyces Blakesleean.ns than was to be expected froin a previously determined dry weight of the organism grown in liquid culture with the same quantity of thiamine. The purpose of this investigation was to find out whether or not the use of heat in removing and washing the mycelium grown on the agar mediawas responsible for this difference in dry weight. The inhibiting effect of agar on the growth of Phycomyces also was inivestigated.