摘要:

AbstractFive fungal plant pathogens were investigated for theirin vitroandin vivoability to produce pectolytic enzymes. OnlyFusarium solanidid not produce any appreciable amount of enzymesin vivoandin vitro.Alternaria solani, Collectotrichum truncatum, Colletotrichum capsiciandCurvularia pallescensproduced pectolytic enzymesin vitrowhich were detected after ten‐fold concentration of the cultures by ammonium sulphate precipitation. These same four fungi produced pectolytic enzymesin vivowhich were detected after twenty‐fold concentration of blended infected host tissue. The pH values of peak enzyme activity of 3.0 and 5.0 indicate that the enzymes produced were polygalacturanaes. The monogalacturonide end‐product of sodium polypectate and cell wall degradation indicate that exopolygalacturonases were produced by the pathogens. The low concentration of these enzymes in infected host plant tissues and the slow pectate‐splitting action of the exopolygalacturonases produced may account for the slow development and the dry necrotic nature of the disease these fung

ISSN:0233-111X    

DOI:10.1002/jobm.3620270702

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractEffects of nicotinamide (NA) on the development of heat resistance and sporulation inBacillus cereusT were studied. It was observed that NA produces more than 95% heat labile spores (80°C for 30 min). The growth and the utilization of poly‐β‐hydroxybutyrate (PHB) is not affected. The heat labile spores were morphologically comparable to untreated spores but the levels of spore specific proteins and dipicolinic acid (DPA) were only 15–20% of the maximum. NA‐treated spores germinate poorly ( 10%) and a storage of 2 months at 4°C causes complete loss of germination characteristics. However, the exogenous addition of DPA or l‐kynurenine completely reverses all effects indicating a possible involvement of L‐tryptophan metabolism in the development of h

ISSN:0233-111X    

DOI:10.1002/jobm.3620270703

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620270705

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractForty four samples collected from animal and bird pens were screened for their content of saprophytic fungi by using the dilution plate method. 76 species in addition to one variety ofAspergillus flavusbelonging to 33 genera were recovered on three types of media: 20 genera and 49 species on LITTMAN‐oxgall agar, 19 genera and 41 species on cellulose‐ and 19 genera and 43 species on glucose‐Czapek's agar. The most frequent genera wereAspergillus(21 species),Scopulariopsis(4 species) andPenicillium(10 species). Among the isolated fungiA. fumigatus, A. flavus, A. terreus, A. niger, A. sydowi, A. nidulans, S. brevicaulis, S. brumptii, P. chrysogenumandP. funiculosumwere the most common sp

ISSN:0233-111X    

DOI:10.1002/jobm.3620270706

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620270708

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe fine structure changes of a high producingClaviceps paspalistrain during submerged cultivation were followed by means of different electron microscopy techniques. Considerable changes in ultrastructure have been found between the vegetative and the production mycelium particularly in the 4‐day‐old production mycelium. In this state freeze‐fracturing micrographs reveal a number of “section” vesicles and vacuoles mediating communication between the growing and producing cells and the external milieu. Abundant signs of secretory activity on the plasma membbrane are possible sites of alkaloid

ISSN:0233-111X    

DOI:10.1002/jobm.3620270709

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe study was undertaken to characterize the kinetics of possible bacterial synergy using a mouse model of mixed intraabdominal infection withBacteroides intermediusandFusobacterium necrophorum.Female CD‐1 mice were injected intraperitoneally withB. intermedius, F. necrophorumor mixtures of both organisms. Generalized septic peritonitis developed within 24 hr, with abscess formation occurring after one to two wk in survivors with the mixed infection. Involvement of the reticuloendothelial system was evidenced by dose‐dependent hepatosplenomegaly, which appeared during the first wk postinfection and progressed throughout the course of the exepriment. Indirect immunofluorescence confirmed the presence of both species of bacteria in frozen sections of liver tissue. The median lethal dose (LD50) was 2.11 × 109for the mixture, 3.03 × 109forB. intermediusalone, and 1.07 × 109forF. necrophorumalone. The median abscess‐producing dose (AD50), the dose required to produce abscessess in fifty percent of the surviving mice at two wk, was approx. 1/100 of the LD50dose. The AD50for intrahepatic abscesses was 2.8 × 108for the mixture, whereas the AD50for intraabdominal abscesses occurring in any site was 5.14 × 107. BothBacteroidesandFusobacteriumpersisted in tissue for at least 22 wk following mixed infection. The persistence of theBacteroidesin tissue represents a synergistic result of mixed infection withFusobacteriumand contributed to the chronicity of intraabdominal abscess formation.Bacteroides, injected alone, did not produce abscesses at any of the doses tested. However, when passaged (isolated from mixed infection hepatic abscesses)B. intermediuswas used, the bacteria did induce

ISSN:0233-111X    

DOI:10.1002/jobm.3620270710

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe effect of different O2concentrations on denitrification in freshwater sediment was studied using the acetylene blockage technique. Denitrification occurred over a wide range of O2concentrations ranging from 10.1 to 0.33 μmol ml−1in nitrate amended sediment. However, denitrifying activity was not observed in sediment incubated under similar conditions when NO3‐was absent. These observations suggested that an anoxic environment or low O2concentrations were not required for denitrification to occur, if NO3‐ was initially present in the sediment. Denitrification gradually decreased as the dissolved O2concentration in sediment increased to 0.25 μmol ml−1. However, between 0.25 and 0.35 μmol ml−1dissolved O2, denitrifying activity was higher than at the lower dissolved O2concentration (0.2

ISSN:0233-111X    

DOI:10.1002/jobm.3620270711

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620270712

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe accumulation of glycerol was investigated in threeAspergillusspecies,A. niger, A. ochraceusandA. tamariiafter being grown in media containing different NaCl concentrations. Intra‐extracellular as well as total glycerol were markedly accumulated by the three organisms in response to increased salinity. However, at salinity levels of 10–14% NaCl, extracellular glycerol was somewhat lowered. In addition, it was found that the maximum accumulation of glycerol inA.niger andA. tamariiwas reached within the first 10 hours after salinization. However, after desalinization, the extracellular glycerol was continuously increased within the first 6 hours at the expense of intracellular glyce

ISSN:0233-111X    

DOI:10.1002/jobm.3620270713

出版商:Wiley‐VCH    

年代:1987

数据来源: WILEY