Diethyl pyrocarbonate (DEPC) inhibited the intracellular growth of Lactobacillus casei phage J1. At bacteriostatic concentrations of DEPC (0.5-8mM) growth inhibition of the phage was reversible; after the decomposition of DEPC into ineffective components the phage burst began to occur with a prolonged latent period. At bactericidal concentrations of DEPC (10mM or greater) growth inhibition of the phage was completed and irreversible; the number of infective center rapidly decreased and, thereafter, did not increase. DEPC (10mM) blocked the lysis of phage-infected cells. Artificial lysis of the lysis-inhibited cells revealed no intracellular mature phage particles. DEPC blocked an early stage(s) of phage growth, resulting in an inhibition of the synthesis of phage structural proteins, including antigenic materials having serum-blocking power, and phage DNA. However, DEPC seemed not to react with the injected phage DNA. The addition of DEPC at any time during the latent period also produced an immediate inhibition of the syntheses of phage protein and phage DNA and the cellular lysis, even after these had been initiated. The results are discussed in relation to the control of phage infection in dairy fermentation.
The fatty acid composition of lichens and their symbionts was determined. In lichens, linoleic and oleic acids were the most abundant and these acids were also rich in their phyco- and mycobionts. A small amount of arachidonic acid was detected in some of the lichens and their phyco- and mycobionts.
The amount of growth and external morphology of Candida albicans growing in a defined medium was influenced by the amount of yeast extract supplemented to the medium. With 10mg/ml of yeast extract a maximum growth exclusively consisting of yeast-like (Y) morphology was obtained, while cells grown in a medium containing a suboptimal concentration of yeast extract for growth (1mg/ml) predominantly developed into filamentous (F) form. Comparative study of macromolecular content of both Y and F phase cultures revealed that RNA and protein levels in the former culture were 5- and 2-times higher, respectively, than those of the latter, although values for both cultures fluctuated to some extent during 24hr of incubation. DNA content was nearly the same in both phases. When stationary phase Y cells were placed in the yeast extract-optimal fresh medium, transient repression of respiration induced by glucose in the medium was observed as is known to be characteristic of facultative microorganisms. In contrast, the respiratory pattern of F cells transferred into the yeast extract-suboptimal medium was significantly different from that of Y cells and rather comparable with that of obligately aerobic yeasts like Rhodotorula sp. Such a correlation of macromolecular composition and respiratory pattern with developing cell morphology was ascertained by experiments, in which Y to F and F to Y phase conversion were induced by transferring initial Y phase and F phase cells into yeast extract-suboptimal and -optimal media, respectively.
The structure of both yeast-like (Y) and filamentous (F) phase growth of Candida albicans, morphogenesis of which was controlled by the different concentration of yeast extract added to the culture medium, was studied on electron micrographs of ultrathin sections. Parallel studies were also carried out by phase-contrast microscopy on external morphology of living cells. Compared to Y-phase cells which exhibited essentially the same cytology as that noted for C. albicans or Saccharomycescerevisiae by many workers, F-phase cells were distinctly characterized by the extensive development of intracytoplasmic membrane systems (ICMS) and endoplasmic reticulum. Such ICMS appeared to originate from the cell membrane and, frequently, to form whorled structures composed of multiple layers of a unit membrane, resembling in appearance the corresponding structures reported for several filamentous fungi.
The ability of different locally isolated fungi to transform cortisol to its Δ1-dehydro derivative (prednisolone) was investigated. The desired reaction was performed by some organisms; namely, Fusarium oxysporum 153, F. moniliforme 2 and 157, F. solani, Gliocladium sp., and Helminthosporiumspeciferum. Reduction of the 20-keto group of prednisolone was observed with F. oxysporum 153, F. moniliforme 2, and Gliocladium sp. Study of the convertibility of cortisol with the most active fungus (F. oxysporum 153) revealed the existence of Δ1-dehydrogenase and 20β-keto reductase systems which exhibit different velocities and activities. The dehydrogenation reaction proceeds faster during the early stages of fermentation, while the reductase system attains its maximal activity at later stages of the transformation period.
The resolution of different steroids on a thin-layer plate with a large number of solvent systems was investigated. These steroids are of the pregnene models differing in the number and position of the double bond, and ketone and hydroxyl groups. The mobility of these steroids on the plate with the most suitable solvent systems (9 different systems) was described. The characteristic colours of the tested steroids upon using different colour reagents are also given. The results of these studies may be of importance to workers interested in the field of microbiological transformation of steroids; especially those concerned with the study of dehydrogenation reactions.
Hundreds of strains of methanol-assimilating yeasts were isolated in pure culture from a wide variety of natural sources through investigations on industrial cell production and the metabolism of methanol. Seven of these strains showed heavy growth on a methanol medium. Taxonomic studies on these strongly methanol-assimilating yeasts indicated that five strains were the same species and belonged to a new species, Pichia methanolica, one strain Pichia pastoris, and another Candidaboidinii.