摘要:

Various isolates ofTrichodermaspp. formed chlamydospores in oat kernels placed in sterile and natural soils and in excised tissues of corn and bean inoculated with a conidial suspension. In an axenic oat – loam soil system, isolates of three species (T.viride,T.harzianum,T.hamatum) produced 1–38 × 107chlamydospores/g of oat tissue. The soil type and its organic matter content did not affect the number of chlamydospores formed. In oat kernels retrieved from natural soils infested withTrichodermaconidia, approximately 10% were chlamydospores of indigenousTrichodermaspp. that infested and colonized the oats. Another 10% were attributed to the isolates added to soils as conidia. The remaining chlamydospores belonged toFusariumspp., unidentified fungi, or were nongerminable on the media used. In excised corn and bean tissues infested withTrichoderma, from 19 × 106to 61 × 106chlamydospores/g of tissue were formed by the phyllosphere fungi. Ten percent of the chlamydospores were from the introduced isolates and the remainder from indigenousTrichodermaspp.,Fusariumspp., and unidentified fungi. The results suggest the probable importance ofTrichodermachlamydospores in the survival of this genus in soil.

ISSN:0008-4166    

DOI:10.1139/m84-001

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Polyphosphate bodies and acid phosphatase activity were characterized inNostocsp. to determine if the hydrolysis of polyphosphate bodies occurs during dark (energy stress) periods. Electron and light microscopy were used to locate polyphosphate bodies. Acid phosphatase activity was measured usingp-nitrophenyl phosphate as the substrate to determine net changes in the level of the enzyme activity. To induce energy stress,Nostocsp. cells were kept in the dark for 72 h to deplete stored carbon compounds. Cells incubated in the light for 72 h (controls) showed acid phosphatase activity localized around the perimeter of polyphosphate bodies. When cells were incubated in the dark, acid phosphatase activity occurred throughout the polyphosphate body matrix. However, complete hydrolysis of the polyphosphate body did not occur and the rate of acid phosphatase activity was not affected.

ISSN:0008-4166    

DOI:10.1139/m84-002

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Pyruvate kinase from the filamentous, citric acid producing fungusAspergillus nigerwas purified about 100-fold by ammonium sulfate precipitation, DEAE-cellulose chromatography, and gel filtration. The addition of fructose-1,6-diphosphate was necessary to prevent loss of activity during purification. The enzyme purified in the presence of fructose-1,6-diphosphate (FDP) exhibits hyperbolic kinetics with respect to phosphoenolpyruvate (PEP) and ADP. Monovalent cations activated the enzyme (K+, NH4+). FDP neither activated nor inhibited the enzymatic activity from extracts freshly prepared in the absence of exogenous FDP; ATP showed a weak activation. In contrast the enzyme from crude extracts which had been stored in the presence of glycerol for 3 days showed activation by FDP or a metabolite thereof and inhibition by ATP. In the absence of FDP sigmoidal kinetics were obtained with respect to PEP, which became hyperbolic kinetics after addition of FDP. ATP inhibition turned into slight ATP activation in the presence of FDP. However, it was possible to reactivate inactivated pyruvate kinase (after dialysis in the absence of FDP) by adding FDP to the enzyme assay. From these results and because of the very high affinity of pyruvate kinase for FDP (Ka < 0.1 μM), it is concluded that the enzyme probably has FDP bound to the proteinin vivo. The significance of this hypothesis to the regulation of glycolysis inA.niger, with special reference to the mechanism of citric acid accumulation, is discussed.

ISSN:0008-4166    

DOI:10.1139/m84-003

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Gamma-irradiated peat was used to prepare inoculants for 10 different species of tropical legumes. These inoculants were sent to cooperators in 14 cities in 13 tropical countries. Each cooperator received a package containing a maximum recording thermometer, plating-media components, special instruction sheets, and inoculants. Control experiments were pursued in the laboratory by exposing the various inoculants to 28, 37, and 46 °C. Temperatures reached in the inoculants during their transportation varied from 26 (Mexico) to 45 °C (Kenya). Arrival time of the inoculants ranged from 6 days (Hissar, India) to 54 days (St. Augustine, West Indies). Although a total loss of viability was reported for the chick-pea inoculant (Saudia Arabia) and a severe decrease in two others (bean and lentil inoculants in Kenya and Saudi Arabia, respectively), over 90% of the inoculants received had viable counts in excess of 1 × 108cells per gram of moist peat. Laboratory data indicated that 28 °C was optimal for multiplication to maximal numbers in excess of 1 × 1010cells per gram of moist peat. Six inoculants studied for long-term storage showed excellent quality for 24 weeks at 28 °C. At 37 °C the cell multiplication was comparable with that at 28 °C with 8 of the 10 strains only during the 1st week. For all strains, 46 °C was lethal. Large reductions in viable counts were observed during inoculant preparation when broth cultures were added to peat.

ISSN:0008-4166    

DOI:10.1139/m84-004

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

An induced mutant ofCandida albicanswith greatly decreased virulence for mice is described. The mutant was one of five auxotrophic mutants obtained by ultraviolet irradiation of a clinical isolate (strain MY 1044). The five mutants included two methionine auxotrophs, one methionine–cysteine auxotroph, one temperature-sensitive serine auxotroph, and one auxotroph with unknown growth requirements. Each of the mutants produced normal mycelium and had a normal profile of susceptibility to four antifungal drugs. The virulence of each mutant was compared with the parent strain by LD50determination in mice. Four of the five auxotrophs exhibited LD50's that were not significantly different from the parent strain (mean LD50 = 7.5 × 105cells). However, the temperature-sensitive serine auxotroph was significantly less virulent than the parent strain (LD50 > 107cells), even though it grew wellin vivoand in mouse serum at 37 °Cin vitro. Use of this mutant in conjunction with its "isogenic" parent should help to elucidate true virulence factors inC.albicans.

ISSN:0008-4166    

DOI:10.1139/m84-005

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Flocculating ability in yeasts of the genusSaccharomyceswhich cause the spontaneous fermentation of grape musts is not rare. About 6.8% of isolates are flocculent. The strains show a different degree of flocculation and also variable developmental behaviour. The genetic analysis, carried out immediately after strain isolation and again after 3 years, shows that only flocculating homozygote strains ensure the stability of the flocculation character over time. Flocculation of some strains shows a degree of instability in the expression of the character which is typical of cytoplasmic inheritance.

ISSN:0008-4166    

DOI:10.1139/m84-006

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

This study showed inAcholeplasma laidlawiithe possibility of transformation and fusion of protoplasts after induction by polyethylene glycol. Recombination in a genome of the resistance to chloramphenicol and neomycin has been obtained. Minimal inhibitory concentraiton of these antibiotics towards the recombined strain are identical to those measured with the parental strains. The most suitable experimental conditions have been studied. It appeared that the fusion, which is carried out more easily than the transformation, led to a higher frequency of recombination.[Translated by the journal]

ISSN:0008-4166    

DOI:10.1139/m84-007

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Several biochemical properties of a mutant deficient in phosphoglucose isomerase (pgi) ofCoprinus cinereuswere examined in connection with its ability to produce basidiocarps. Mycelium of thepgimutant accumulated glucose-6-phosphate and showed higher glucose-6-phosphate dehydrogenase activity than wild type. A conventional fruiting medium did not support basidiocarp formation by the homozygous dikaryonpgi/pgi, but the addition of a reduced amount of glucose plus a compensatory amount of fructose to the culture medium resulted in partial recovery of fruiting ability. This modification of the culture medium decreased the intracellular glucose-6-phosphate to almost the same level as in the wild type. The addition of polyols such as mannitol resulted in complete recovery of fruiting ability by the dikaryonpgi/pgiwithout affecting the level of glucose-6-phosphate. Mycelium of the mutant showed an elevated activity of NAD-linked polyol dehydrogenase and an elevated intracellular NAD level, irrespective of whether the mycelium was grown in the presence or absence of polyol.

ISSN:0008-4166    

DOI:10.1139/m84-008

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Pilated gonococci added to human erythrocytes apparently bind to polypeptide band 3 and inhibit chloride–bicarbonate exchange across the membrane in contrast with nonpilated organisms. Known covalent inhibitors of anion transport (4,4′-diisothiocyano-2,2′-disulphonic acid stilbene and α-cyano-4-hydroxycinnamic acid) inhibit chloride efflux from erythrocytes and also reduce hemagglutination titres, strongly suggesting that band 3 is the major host-cell receptor involved in all interaction between gonococci and erythrocytes. In studies of other cell species, however, band 3 prepared from human erythrocytes inhibited adherence of pilated gonococci to human foreskin and HeLa cells, but was without effect in human buccal, Vero, and mouse L cells.

ISSN:0008-4166    

DOI:10.1139/m84-009

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Protoplasts were obtained fromHyphoderma roseum(Fries) andCunninghamella elegans(Lendner), fungi capable of steroid 11-hydroxylation. The lytic enzyme preparation was derived fromTrichoderma virideCBS 354-33. Homogeneous protoplast suspension, free of mycelial debris and cell wall fragments, transformed cortexolone and 6α-fluorocortexolone-16,17-acetonide to the same products as the intact mycelium of the microorganisms. Liberation of protoplasts and their stabilizaiton during steroid transformation was the most effective in 0.8 MMgSO4; still, this compound impaired steroid hydroxylation. Consequently, the concentration of the transformation product formed was nearly the same as in sucrose, mannitol, and sorbitol, compounds which caused no inhibition but which were less effective stabilizers.

ISSN:0008-4166    

DOI:10.1139/m84-010

出版商:NRC Research Press    

年代:1984

数据来源: NRC