摘要:

AbstractThe cytogenetic effects of fungal metabolites produced by 113 strains belonging to 36 fungal species and isolated from 5 substrates of commercial poultry feedstuffs were tested for their effect on the growing root meristems ofAllium cepa.The fungal metabolites ofPaecilomyces canescens, Aspergillus fumigatus, Syncephalastrum racemosum, Aspergillus terreusandMucor hiemalisstrongly suppressed cell division. Metabolites from other strains had less effect on cell division but permitted the appearance of several abnormalities through different mitotic stages. In general, chromosomal aberrations were more obvious with metabolites ofAspergillusspecies,Mucor circinelloidesandCladosporium cladosporioides.The mutagenic effects produced by these fungal metabolites reflect the risk that might take place through the consumption of these contaminated feedstuffs.

ISSN:0233-111X    

DOI:10.1002/jobm.3620290302

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620290304

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

摘要:

AbstractWe isolated a tryptophan auxotrophic mutant strain, PK101, ofPichia guilliermondii. Its auxotrophy is not caused by a defect in any of the tryptophan biosynthetic enzymes, but its chorismate mutase, an enzyme of the phenylalanine‐tyrosine biosynthesis, is changed. In comparison to the wild type chorismate mutase, the enzyme of PK101 is characterized by a complete loss of sensitivity to L‐phenylalanine inhibition and to a considerable loss of sensitivity to L‐tryptophan activation. Furthermore, the chorismate mutase activity of the mutant is more than 7‐fold higher in the absence of L‐tryptophan than in the wild type. The PK 101 enzyme is also changed in the pH optimum and in some kinetic constants. We found an increased intracellular pool of both phenylalanine and tyrosine, and a reduced content of tryptophan in the mutant cells. Our genetic data indicate that the mutant phenotype is dominant over the

ISSN:0233-111X    

DOI:10.1002/jobm.3620290305

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

摘要:

Abstract26‐Deoxylaidlomycin (I, C37H61O11Na) was isolated together with its cometabolite laidlomycin (II) from the mycelium ofStreptoverticillium olivoreticuliIMET 43782. Its structure was determined by high‐field13C and1H NMR, and MS spectral studies. The antibacterial activity of I againstBacillus subtilisATCC 6633 was found to be approx. four times higher than that of laidlomycin (II).CALLING STATEMENT :.The structure of 26‐deoxylaidlomycin (I: sodium salt,R1= Na,R2= H): III free acid:R1,R2= H and laidlomycin (II, sodium salt:R1= Na;R2

ISSN:0233-111X    

DOI:10.1002/jobm.3620290306

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620290308

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

摘要:

AbstractHistidine auxotroph ofRhizobium melilotistrain L5.30 was isolated by nitrosoguanidine (NTG) mutagenesis. On alfalfa it formed ineffective nodules that contained only a few degenerating bacteroids inside large vacuoles but many starch granules. Prototrophic forms of this mutant (revertants and transductants) formed pink, effective nodules. Effective nodules were also induced by the His−mutant when histidine was supplied to the plant‐growth medium; this supported the supposition of a causal relationship between histidine auxotrophy and ineffectivity in theR. melilotistrain L5.30.The histidine mutation of the strain studied was mapped onto the chromosome ofR. melilotiby transduction near earlier localizedcys‐246auxotrophic mutation (4.4% of cotransduc

ISSN:0233-111X    

DOI:10.1002/jobm.3620290309

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

摘要:

AbstractWhen 20 μM of carbonyl cyanide‐m‐chlorophenyl hydrazone (CCCP) were added to a M medium containing glucose as an energy source at pH 7.6, theEscherichia coliK12 strain 3301 was able to grow, whereas on the medium containing NaCl above 200 mM, the growth was remarkably suppressed by the addition of 20 μM CCCP. Furthermore, when glucose was replaced by either glycerol or lactate as an energy source, no growth occurred in the presence of 20 μM of CCCP. When glycerol was used as a substrate, O2consumption by whole cells was observed in the presence of 20 μM of CCCP, but not in the case of lactate. We found that14C‐lactate uptake was completely inhibited by the addition of 20 μM of CCCP. The cells, which were incubated for 24 h on a M medium containing glucose in the presence of 20 μM of CCCP produced many more organic acids (mainly, acetate and lactate) than was the case in its absence. It appears that the influx process of external lactate when this was added as an energy source, was completely inhibited by addition of CCCP (20 μM), but the efflux process of lactate that was produced by glycolysis, was not influenced by this protonophore. On the other hand, it is suggested that on the hyposalts medium, a proton motive force (pmf) is not necessary for the growth of the strain 3301, whereas pmf is necessary for gro

ISSN:0233-111X    

DOI:10.1002/jobm.3620290310

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620290312

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effects of temperature on storage and viability of asexual spores ofRhizomucor pusillus(LINDT) SCHIPPER andRhizomucor miehei(COONEY and EMERSON) SCHIPPER were studied. An optimal germination temperature of 35 °C was recorded for both species with good results obtained around 40 °C. On prolonged storage of the spores at various temperatures (‐19 °C, 4 °C, 30 °C, 37 °C), the best results were obtained at 4 °C and 30 °C. Very rapid losses in viability of the spores of both fungi occurred at −19°C reaching a maximum of 68% and 51%, respectively, forR. pusillusandR. mieheiafter 6 months of storage.Continuous exposure of the spores to 68 °C led to rapid losses of viability of up to 100% for those ofR. pusillusafter 40 min exposure. Sporangiospores ofR. mieheishowed more gradual losses on exposure to 68 °C.The potential health hazards which the presence of these fungi on tobacco products pose to man

ISSN:0233-111X    

DOI:10.1002/jobm.3620290313

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620290315

出版商:Wiley‐VCH    

年代:1989

数据来源: WILEY