Various conditions affecting the cobiontic formation of red pigments caused by Penicillium verruculosum L 9 and Trichoderma viride L 6, were investigated and the following results were obtained. When grown together on an agar plate the pigment formation was not affected by the initial pH in the range from 4.0 to 8.0. When grown in a liquid medium on a shaker, the optimum pH for the pigment formation was found to be at 6.0-7.0. On inoculating the spores of T. viride into precultures of P. verruculosum of varying length, it was found that the red pigment formation decreased remarkably when the preculture of the latter lasted more than 6 hours. Conversely, on inoculating the spores of P. verruculosum into precultures of T. viride of varying lengths, the amounts of the red pigments formed were almost the same as that in the control culture, except in the cases of 7 and 8hours precultures, in which the red pigment formation was considerably less. The red pigments were scarcely produced when the ratio of inoculum sizes (spores) of P. verruculosum to T. viride, was 5: 1-15:1, while a distinct pigment formation occurred when the ratio in question was 1:5-1:15. Vigorous aeration of the culture medium was necessary for the red pigment formation and it was inferred that a close relation may exist between the sporulation of P. verruculosum and the cobiontic red pigments formation. The red pigments were produced over the temperature range of 20° to 30° where both test molds could grow well, the optimal temperature being found in the range of 25° to 30°.
The effect of nutrient substances upon the production of red pigments by interaction of Penicillium verruculosum L 9 with Trichoderma viride L 6 were investigated and the following results were obtained. A medium containing 1.0% of glucose, 1.0% of Difco-peptone and adjusted pH to 6.0 was found to be the best as a non-synthetic medium. Among a number of carbonic materials tested (hexoses, pentoses, disaccharides, polyalcohols, organic acids, and alcohols) only mannose and malic acid gave positive results comparable to that observed with glucose. No pigment formation took place when inorganic nitrogenous materials such as NH4OH, NH4Cl, (NH4)2SO4, NH4NO3 and (NH4)2CO3 were added as a sole nitrogen source to the semi-synthetic medium. The red pigment formation comparable to that obtained with the glucose-peptone medium could be induced when 1.0% of either casamino acid, urea, L-arginine HCl or DL-proline was added as a nitrogen source to a medium consisting of 4% glucose, 0.1% MgSO4.7H2O, 0.1% MnSO4.4H2O, 0.5% KH2PO4 and 0.01% ZnSO4. The concentration of L-arginine HCl and of DL-proline in theab ove-mentioned medium, which caused maximum formation of the red pigment was 1.0% and 2%, respectively. The red pigment formation was not influenced by the presence or absence of various vitamins such as thiamine, pyridoxal, p-aminobenzoic acid, panthothenic acid and nicotinic acid.
(1) The effect of inoculating the paddy field with nitrogen-fixing blue-green alga: Tolypothrix tenuis upon the yield of rice plant was investigated at nine experimental farms located in various districts through Japan. (2) The experiments conducted during five successive years showed that the amount of ammonification was higher in inoculated soils than in non-inoculated ones. (3) On an average the increase of rice crop obtained by inoculating the alga in relatively nitrogen-poor paddy fields was: 2.0% in the first year, 8.0% in the second year, 15.1% in the third year, 19.5% in the fourth year and 10.6% in the fifth year. (4) The fact that the favorable effect of algal inoculation increased year by year may be attributed to the accumulation in the paddy field of the algal cells which would be partially decomposed and partially remain and proliferate in the following years to increase, at any rate, the nitrogenous fertility of the paddy soil.
By plating spores of two auxotrophic mutants of Rhizopus javanicus on a medium supplemented with limited amounts of nutrients, heterocaryotic colonies were obtained in frequencies of 10-4 to 10-5. Upon formation of spores, eighteen of the colonies gave spores of both component types (mycelium-type heterocaryons), while one gave, besides spores of component types, prototrophic spores (spore-type heterocaryons). The prototrophs segregated the three types repeatedly, in no case giving rise to a recombinant.
Using a strain of Saccharomyces cerevisiae grown in malt extract at 30°, it was found that at the 24th and 48th hour of culture, the fractions of the cells without buds were about 0.8 and 0.7, respectively. By the measurements of size distribution, the cells without buds were found to be oblate in shape.
The densities of cell suspensions of Saccharomyces cerevisiae, the density of the suspending medium (phosphate buffer) and the volume fraction of the cells in suspensions were measured to calculate the density ρy of the yeast cell. The value of ρy was determined to be 1.0725±0.0012(g/cm3). The relative viscosities of the cell suspensions were found to be markedly lower than the values calculated from relevant equations thus far presented by various workers for the viscosity of suspensions.
Hindered settling velocity of yeast cells, Saccharomyces cerevisiae suspended in a buffer solution was measured. So far as the experimental range used in the present study was concerned, the results obtained were substantially identical with those reported for other suspensions. It was shown that the shape of particles, irrespective of whether they are "isolated" or "flocculated", could be correlated in quantitative terms to the relative velocity of hindered settling which is controlled by the viscous force of liquid. In connection with this, further studies on the shape of flocs and the degree of flocculation, an evaluation of which is frequently required in handling microbial suspensions, seem to be fruitful.