In an attempt to cultivate entodinia in a chemically defined medium, the nutritional requirement was studied by replacing the fractions of white clover with known substances. Nutrients, including the fractions of white clover, were given to the protozoa in a particulate form to facilitate the uptake of foods. It was found that the lipid fraction was essential and that the water-soluble fraction was stimulatory for protozoal growth in a medium ontaining casein, proteose-peptone, and amylopectin. The water-soluble fraction was replaceable by soluble starch, glucose, ribonucleic acid, vitamins, and minerals. The lipid fraction was further fractionated systematically, and the results showed that the essential factors were contained in the digitonin- precipitated fraction. Three sterols, i.e., β-sitosterol, stigmasterol, and campesterol, were identified in this fraction. The requirement for white clover lipids by entodinia was completely satisfied by these sterols. Cholesterol was also effective, but ergosterol, lanosterol, and squalene had no effect. Entodinia were successfully grown for more than 100 days in the medium which consisted of casein, proteose-peptone, amylopectin, soluble starch, glucose, ribonucleic acid, vitamins, minerals, and β-sitosterol.
Patulin and diacetoxyscirpenol are potent inhibitors of the sporulation of fungi, Aspergillus flavus, A. niger, Penicillium expansum, Neurospora crassa, Cladosporium herbarum, Rhizopus nigricans, Thamnidium elegans, and Mucorspinosus. The toxicity of diacetoxyscirpenol is markedly higher than that of patulin. The rate of spore production decreases with increasing toxin concentration and is totally suppressed by 100μg/filter disk. The phycomycetes tested are especially sensitive. Patulin suppresses the germination of the spores of Cladosporium herbarum, Rhizopus nigricans, and Thamnidium elegans almost completely in 100μg amount whereas diacetoxyscirpenol shows this effect only in the last mentioned fungus. Thamnidium elegans is very sensitive to all mycotoxins so far tested.
Germinating spores of Bacillus subtilis were freeze-dried and irradiated with ultraviolet ray (UV) while dry or after rehydration. It was found that the extremely high UV-resistance of the spores in the transient stage, through which germination proceeds, is lost by freeze-drying and is rapidly restored by rehydration.
Non-foaming mutants of Saké yeast (Saccharomyces cerevisiae) which do not form froth head during fermentation differ in various physicochemical properties from their parent strain. In the work, the cell wall composition was compared between parent strain and two strains of the mutant. Flotability of the mutant cells increased by mechanical disruption of the cells, suggesting that the disrupted cells have higher flotability regardless of the kind of yeasts, i.e., foaming or non-foaming. Contents of total carbohydrate, nitrogen, ash, glucan, mannan, glucosamine, and phosphorus as well as amino acid composition were determined repeatedly. Results showed that there were no marked differences in the cell wall composition between the parent and mutant strains, as can be detected directly by the ordinary chemical analyses.
Baker's yeast showed periodical changes in cysteine (CyH) desulfhydration activity with cell growth, and the crude extract from young pantothenate-deficient (PaA-) cells had 1.6 times higher activity than that of pantothenate-sufficient (PaA+) cells of the same growth phase. PaA- cells were also stronger in sulfite reductase activity as examined in 0.6M phosphate buffer. PaA- cells were thus endowed with H2S producibility, although the yeast had more intensive CyH synthetase activity than CyH desulfhydrase one, irrespectively amount of pantothenate supplied. Of pooled amino acids, a larger amount of serine was found in PaA+ cells while CyH only in PaA-cells. A DEAE-cellulose column chromatography of the crude extract enabled separation of unstable CyH desulfhydrase from stable CyH synthetase, and each enzyme, which resembled each other in property, was purified to almost homogeneous level. In Km for CyH desulfhydration activity, CyH desulfhydrase had exceedingly lower value (3.4×10-4M) than CyH synthetase (reversed) (2.0×10-2M), and thus the former enzyme seemed likely to take a predominant part in cell CyH desulfhydration. Adenosine triphosphate (ATP) as well as S-adenosylmethionine could inhibit CyH desulfhydrase at acid pH while ATP stimulates it at alkaline pH, although ATP was inert to CyH synthetase. A sigmoid curve was depicted in the activity-substrate concentration relation at pH 6.9, and 14C-ATP-enzyme complex was obtained from a mixture of CyH desulfhydrase protein and 14C-ATP when incubated at 30° for 30min. Thus ATP-effect seems likely to occur on the basis of allosteric inhibition, presumably playing a modulating role in prevention of CyH once synthesized from its degradation in yeast sulfur metabolism. A possible mechanism for H2S evolution due to PaA deficiency in PaA-requiring yeast was presented.
β-Propiolactone exhibited a bactericidal effect on Lactobacillus casei. β-Propiolactone inhibited the synthesis of DNA under conditions which allowed the synthesis of RNA and protein. β-Propiolactone inactivated free phage J1. The inactivation rate of phage by β-propiolactone depended on pH and temperature. Almost all of metal cations protected the phage against the effect of β-propiolactone, whereas Fe2+ enhanced the inactivation rate of phage by β-propiolactone. β-Propiolactone reacted with phage DNA to cause single-strand scissions in the DNA, thus resulting in phage inactivation. β-Propiolactone hardly affected the adsorption of phage and injection of phage DNA, but inhibited the intracellular growth of the phage. β-Propiolactone blocked the synthesis of phage DNA, structural protein of the phage and phage endolysin. β-Propiolactone added later in the latent period did not inhibit growth of the phage. A primary and major action of β-propiolactone seems to be its reaction with the injected DNA, thus resulting in the prevention of DNA replication. The results are discussed in relation to the control of phages in the dairy fermentations.
The paper deals with the development of ascocarp and nuclear behaviour during the development of ascus and ascospores in Achaetomium uniapiculatum. The ascocarp arises by the coiling of a hyphal branch. The septate ascogonial coil soon becomes surrounded by the vegetative hyphae forming a pseudoparenchymatous spherical body which in later stages gets differentiated into wall layers and central sporogenous tissue. The ascus originates from the penultimate cell of the crozier produced by the binucleate ascogenous cells. As in most of the ascomycetes, in A. uniapiculatum also, four divisions follow karyogamy resulting in binucleate ascospores, each mature ascospore only has a single nucleus the other nucleus probably degenerates. The haploid number of chromosome is 5 (n=5).