Induction by Oxygen of Respiration and Phosphorylation of Anaerobically Grown Escherichia coli

The changes occurring in the respiratory enzymes of anaerobically grown Escherichia coli strain B and E. coli 15 T⁻A⁻U⁻bar during exposure to oxygen were studied. Reduced nicotinamide adenine dinucleotide (NADH) oxidase activity reached its peak soon after O₂ exposure; cytochrome content and succinate oxidase activity increased more slowly, and these increases paralleled each other. The activities of isocitrate and malate dehydrogenases also increased, but the increase was less than that of the succinate and NADH oxidases; exposure to O₂ had no effect on the succinate and NADH dehydrogenase activities. On the other hand, the glycolytic activity decreased slowly after O₂ exposure. The incorporation of ³²P into acid-soluble organic phosphate esters paralleled the respiratory rate during the first 60 min after O₂ exposure, but continued to increase after the respiration reached a plateau. The sensitivity of ³²P incorporation to the uncoupler carbonyl cyanide m-chlorophenylhydrazone also increased with time. The observed relationship between the development of the respiratory chain and the energy-conserving mechanism during O₂ exposure is discussed. Synthesis of the respiratory enzymes upon exposure to oxygen was dependent on concomitant protein and ribonucleic acid synthesis but not on deoxyribonucleic acid synthesis.     

A Method for the Production of Pre-reduced Anaerobically Sterilized Culture Media

A simplified method for the production of pre-reduced anaerobically sterilized media for the cultivation of strict anaerobes is described.     

Aflatoxins of Aspergillus flavus Grown on Cassava

Aspergillus flavus Link ex Fries was grown on cassava (Manihot utilissima) and Czapek-Dox media at 31±1°C and 90 per cent relative humidity for 8 weeks. Isolation and purification of the toxic and carcinogenic metabolic products of the mould by paper and thin layer chromatography are described. High concentrations of aflatoxin B1, B2, G1 and G2 were synthesized by the mould grown on cassava for 4 weeks. In addition to these four major toxic components, 9 other fluorescent materials were observed on the chromatograms of crude products from cassava. It is concluded that the high moisture, high polysaccharide and low nitrogen content of cassava constitute a favourable nutritional condition at high temperatures and high relative humidity for the growth of A. flavus and the synthesis of relatively high concentrations of aflatoxin. This conld represent a serious health hazard in the moist tropics.     

Photosynthetic Development of Anaerobically Grown Rice (Oryza sativa) after Exposure to Air

During anaerobic germination, rice produces a coleoptile devoid of carotenoid and chlorophyll. Further development and greening of the shoot occur upon exposure of the seedlings to air. In this study, a comparison was made between anaerobically (N₂) germinated rice, greened upon exposure to air, and air/dark (A/D) germinated seedlings, greened upon exposure to light. After exposure to air, N₂-grown seedlings had a 76-hour lag before net oxygen evolution occurred compared to a 6-hour lag for A/D-grown seedlings. After 98 h of greening, N₂-grown seedlings reached a rate of oxygen evolution equivalent to that of A/D-grown seedlings after 24 hours. Chlorophyll and carotenoid content showed a similar lag, but did not reach the level found in A/D-grown seedlings even after 124 hours of exposure to air. RuBPcase activity also lagged in N₂-grown seedlings, ultimately reaching greater values than in the `greened' A/D-grown seedlings. Phosphoenolpyruvate carboxylase activity was constant and low in all treatments except for a transient increase after 24 hours of greening of the N₂-grown seedlings.     

High-Level Production of Heterologous Protein by Engineered Yeasts Grown in Cottage Cheese Whey

Cottage cheese whey is a cheese industry by-product still rich in proteins and lactose. Its recycling is seldom cost-effective. In this work we show that the lactose-utilizing yeast Kluyveromyces lactis, engineered for production of recombinant human lysozyme, can be grown in cottage cheese whey, resulting in high-level production of the heterologous protein (125 μg/ml).     

不同CO2浓度下培养的蛋白核小球藻细胞结构的变化

大气 CO2 浓度升高已成为全球关注的一大热点问题 ,CO2 浓度升高对陆生植物影响已有广泛的研究[1] 。但水生植物由于水体中无机碳主要以CO2 -3 、HCO-3 和 CO2 的形式存在 ,所以对大气 CO2浓度升高的响应较为复杂。已有的有关 CO2 浓度与藻类关系的研究主要侧重于高浓度 CO2 对其生理学特性的影响 ,如 :当单细胞绿藻生活在高浓度 CO2( 5 % )的环境中时 ,细胞对 CO2 的亲和力明显降低 ,CO2 补偿点升高 ,碳酸酐酶的活性降低 ,细胞亚显微结构也伴随着明显变化 [2 ,3 ]。但以上的研究均采用很高的 CO2 浓度 (一般为 5 % ) ,而在现实的…     

Unconventional Cell Division Cycles from Marine-Derived Yeasts

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Electron Microscopy of Some Special Cell Contacts in Yeasts

Anastomosis in Endomycopsis javanensis and some other filamentous yeasts was brought about by contact of a denticle from one cell with the wall of another cell, resulting in the disappearance of the outer layer and the thickening of the inner layer of the cell wall of the contacted cell. Another form of contact between cells was the penetration of one cell by a denticle on another cell which had grown out to a stalk; this occurred between cells of E. javanensis and between cells of this species and other yeast species.     

Interactions of Saprophytic Yeasts with a nor Mutant of Aspergillus flavus

The nor mutant of Aspergillus flavus has a defective norsolorinic acid reductase, and thus the aflatoxin biosynthetic pathway is blocked, resulting in the accumulation of norsolorinic acid, a bright red-orange pigment. We developed a visual agar plate assay to monitor yeast strains for their ability to inhibit aflatoxin production by visually scoring the accumulation of this pigment of the nor mutant. We identified yeast strains that reduced the red-orange pigment accumulation in the nor mutant. These yeasts also reduced aflatoxin accumulation by a toxigenic strain of A. flavus. These yeasts may be useful for reducing aflatoxin contamination of food commodities.     

BIOGENESIS OF MITOCHONDRIA : XIII. The Isolation of Mitochondrial Structures from Anaerobically Grown Saccharomyces cerevisiae

Morphologically intact structures have been isolated from anaerobically grown yeast cells which have many of the properties of yeast mitochondria. The structures are about 0.5 µ in diameter and contain malate dehydrogenase, succinate dehydrogenase, oligomycin-sensitive ATPase, and DNA of buoyant density 1.683 g/cc, characteristic of yeast mitochondria. The morphology of the structures is critically dependent on their lipid composition. When isolated from cells grown anaerobically in the presence of supplements of unsaturated fatty acid and ergosterol, their unsaturated fatty acid content is similar to that of mitochondria from aerobically grown cells. These lipid-complete structures consist pre-dominantly of double-membrane vesicles enclosing a dense matrix which contains a folded inner membrane system bordering electron-transparent regions which are somewhat different from the cristae of functional mitochondria. In contrast, the structures from cells grown without lipid supplements are much simpler in morphology; they have a dense granular matrix surrounded by a double membrane but have no obvious folded inner membrane system within the matrix. The lipid-depleted structures are very fragile and are only isolated in intact form from protoplasts that have been prefixed with glutaraldehyde     

Distribution of Cytochrome c Peroxidase Activity in Wild-Type and Petite Cells of Bakers'' Yeast Grown Aerobically and Anaerobically

Studies of mitochondrial biogenesis in yeast have been hampered by a lack of suitable membrane markers in anaerobically grown cells subsequently grown in air. Cytochrome c peroxidase activity and subcellular location was studied to determine whether it would be a useful marker for an analysis of mitochondrial formation. Cytochemical tests revealed enzyme reaction product on all mitochondrial membranes in aerobically grown wild-type cells. Anaerobically grown wild-type and all petite cultures contained cytochrome c peroxidase cytochemical reaction deposits on abundant cytoplasmic membranes and on the few mitochondrial profiles which also were seen in the electron photomicrographs. Biochemical studies corroborated the cytochemistry because mitochondrial fractions were greatly enriched in cytochrome c peroxidase activity for aerobically grown wild-type cultures, but petite and anaerobically grown wild-type cultures showed higher enzyme activities in supernatant fractions than was present in the corresponding particulate fractions after differential centrifugation. Evidence from low-temperature microspectroscopy, spectrophotometric assays of mitochondrial enzyme activities, and electron microscopy showed mitochondrial formation during the time required for preparation and lysis of spheroplasts from anaerobically grown cultures. The data were interpreted as indicating that cytochrome c peroxidase was an oxygen-inducible enzyme, and that there was a developmental relationship between enzyme-reactive membranes of mitochondria and cytoplasm during the period of respiratory adaptation.     

Butyl Rubber Stoppers Increase the Shelf Life of Prereduced, Anaerobically Sterilized Media

Butyl rubber stoppers as compared with neoprene or black rubber stoppers significantly increased the shelf life of prereduced, anaerobically sterilized media for growth of obligately anaerobic bacteria.     

Bacteremia After Tooth Extractions Studied with the Aid of Prereduced Anaerobically Sterilized Culture Media

Both prereduced molten agar and broth and aerobic molten agar and broth were inoculated with blood samples collected from patients with periodontitis, but in otherwise good health, both before and after extraction of two or more teeth. Postoperative blood samples from 23 of 25 patients sampled yielded anaerobic and facultative species. Colony counts from nine samples yielded from less than 1 to over 100 colonies per ml of blood. Organisms detected were species belonging to the genera Bacteroides, Fusobacterium, Peptostreptococcus, Leptotrichia, Propionibacterium, Peptococcus, Veillonella, plus Streptococcus mitis, S. salivarius, vibrio forms, and strains resembling S. mutans. The data indicate that prereduced anaerobically sterilized culture medium with polyanethol sulfonate is effective for detecting anaerobic species in bacteremia and that anaerobic species can be prevalent in bacteremias immediately after tooth extraction in patients with periodontitis.     

UV-Screening Strategies of a Lower Eukaryote Grown in Hydrocarbon Media

In this paper, a detailed analysis of the UV-screening strategies of the fungus Fusarium alkanophyllum is offered using spectroscopic (UV-VIS, FTIR), chromatographic (TLC, HPLC) and physiological analysis methods. Fusarium alkanophyllum showed an optimum growth when exposed to UV radiation at 253.7 (inducing DNA and protein damages) or 354.5 nm (inducing photoxidative damage) in several hydrocarbon media. Further, no ultrastructural difference was seen when cultures were or not irradiated with monochromatic UV. High absorbance between 200–300 nm of F. alkanophyllum indole derivatives, viz. melanin-type pigments, suggests a protector effect for proteins and nucleic acids. The presence of sulfur linked to aliphatic groups in hydrocarbons which is itself a strong UV absorber in the region of λ < 270 nm can explain why mineral oil and kerosene showed high absorptivity at the UVC and UVB ranges. In light hydrocarbon, high absorptivities at the UVB and UVA spectral regions could be explained due to the presence of C–O stretching vibrations corresponding to ketones linked to aliphatic groups. The occurrence of indole derivatives in modern fungi may be a significant relic of the early evolution of microbial pigmentation. Likewise, it is thought that sulfur-enriched heterogeneous hydrocarbon environments could have occurred on the surface of the early Earth and could have absorbed and scattered UV-radiation avoiding or minimizing the damage produced on the biochemical machinery of early microorganisms able to metabolize those hydrocarbons.     

Physiological Properties of Yeast Cells Grown in the Proteolipid-Supplemented Media

Koji mold proteolipid (PL), a high concentration alcohol-producing factor, promoted yeast growth, and also affected the physiological properties of yeast cells: in the conditions of statical cultures, the cells grown anaerobically in PL-supplemented media showed the highest fermentative activity and the highest alcohol-durability by the dipping method in 20% alcohol for 48 hr, at 20°C, that was similar to moromi (main mash) yeasts in Japanese sake brewing; the cells grown in the stationary culture (with cotton plug) supplemented with PL showed the lowest fermentative activity and relatively low alcohol-durability, similar to moto (seed mash) yeasts; the cells grown anaerobically in PL-unsupplemented media showed high fermentative activity but the lowest alcohol-durability.     

Dependence of Vitamin Content in Saccharomyces Yeasts on the Composition of Nutrient Media

The qualitative and quantitative composition of water-soluble B group vitamins in Saccharomyces yeasts cultivated on various nutrient media was studied by high-performance liquid chromatography. New strains of Saccharomyces oviformis Y-2635 and Saccharomyces vini F-5, grown in a nutrient medium with geothermal water, are characterized by increased biological value due to high intracellular concentrations of riboflavin, LB, nicotinic acid, and folic acid.     

Chloroplast Replication in Euglena gracilis Grown in Cadmium-Ion Containing Media

N-(1-Alkenyl)-2-chIoroacetamides, which bear an aryl substituent at the 1-position of the alkenyl moiety, were synthesized and their herbicidal activities were tested. Some of them were active against paddy field weeds. In particular, a new type of chloroacetamide herbicide, 2-chloro-N-methyl-N-(2-methyl-1-phenylpropen-1-yl)acetamide, having no 2,6-dialkyl substituted phenyl moiety, which has been considered essential for activity, was found to be active against barnyardgrass.