ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb03387.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The effects ofBradyrhizobium japonicuminoculation and pre‐plant additions of N fertilizer on soybean (Glycine maxL. Merrill) yields and levels of N2fixation were studied under field conditions at two sites in Thailand. Bacterial inoculants were composed ofB. japonicumstrains selected for high N2fixation levels in Thai soils. Nitrogen fertilizer addition rates used were from 0 to 250 kg N/ha in 50 kg N/ha increments. At the Chiang Mai site in northern Thailand, bacterial inoculation increased nodule weights on plants receiving 100 kg N/ha or less. Increases in nodule parameters due to inoculation were evident at 45 d after planting (DAP) but disappeared by 60 DAP. Addition of N fertilizers decreased the incidence of nodulation and sap ureide contents and decreased the contribution of N2fixation to the N content of plants at maturity as measured by N‐15 isotope dilution methods. At the Kampang Saen site in central Thailand, bacterial inoculation had significant positive effects on nodule numbers and weights, ARA, sap ureide contents and levels of N2fixed as measured by N‐15 isotope dilution methods. Addition of N fertilizers at this site also reduced the effectiveness of N2‐fixing symbioses. It was concluded that small additions of N fertilizer added before planting did not significantly decrease N2fixation levels, but did have a significant positive effect on plant growth. Larger N additions would reduce N2fixation levels in excess of the benefits of adding more N in chemic

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb03388.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

When they were subjected to a range of physical and chemical treatments, spores ofPasteuria penetransshowed properties similar to those of other endospore‐forming bacteria. The spores did not take up some stains, were resistant to desiccation and sonication and showed extrusion of spore contents (‘spore popping’) on prolonged exposure to 0.1% KMnO4in 0.3 n HNO3. Calcium and dipicolinic acid (DPA) were present at concentrations of 0.28% and 0.96% of the spore dry weight respectively, giving a Ca: DPA molar ratio of 1.2. The infectivity ofP. penetransspores was reduced to a low level after heating at 100°C for 5 min, but spore attachment was not markedly affected by heating at 100°C for 15 min. Evidence for the presence of catalase inP. penetransspores was equivocal because the low levels of catalase activity observed in spore suspensions may have been due to contamination from catalase‐positive nematode tissue. WhenP. penetransspores were exposed to a range of substances known to act as germinants for spores ofBacillusspp., germination or loss of refractility was not observed by phase microscopy.In vitroculture ofP. penetranswas attempted by inoculating either spores or vegetative mycelial bodies onto a diverse range of simple and complex media and incubating them in aerobic, reduced oxygen, anaerobic and increased CO2environments. Signs of spore germination or growth of vegetative stages were never

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb03389.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The characterization of the chromosomal beta‐lactamases ofAcinetobacterhas proved difficult because of the poor focusing of these enzymes in conventional isoelectric focusing on polyacrylamide gels. We describe a novel isoelectric focusing method, which employs an agarose gel incorporating a detergent with sorbitol and urea, to examine the beta‐lactamases produced by eight clinical strains ofAcinetobacter calcoaceticus; we have identified four different beta‐lactamases. The molecular masses of each of the beta‐lactamases was estimated and most of them ranged from 600000 to>1000000. These are the largest beta‐lactamases so far described and their size is likely to be one reason for their poor solubility in conventional polyacrylamid

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb03390.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Enrichment in alkaline peptone water was compared with the direct plating method for the isolation ofAeromonasspp. from lamb meat and offal samples. The enrichment method significantly increased the isolation rate of aeromonads. MotileAeromonasspecies (A. hydrophila, A. sobriaandA. caviae) were present in all kinds of samples investigated. Seventy‐threeAeromonasstrains isolated in this survey were characterized to species level and examined for their ability to produce virulence factors. Strains identified asA. sobriawere the strongest producers of haemolysin and enterotoxin, whereasA. caviaestrains were consistently non‐haemolytic and non‐enterotoxigenic. Thus it is likely that lamb meat and offal are potentially significant sources of virulentAeromonasspecies and may play an important role in the aetiology ofAeromonas‐associated gastro‐

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb03391.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Bacteria isolated from purulent processes on the jaws of European hamsters (Cricetus cricetus) and from intestinal inflammatory processes in Syrian hamsters (Mesocricetus auratus), bred as laboratory animals have been shown to be phenotypically similar but not identical withPasteurella pneumotropica. Deoxyribonucleic acid (DNA)–DNA hybridization studies indicate that with one exception, the strains represent two new species of the family Pasteurellaceae. In the absence of a close genomic relatedness to members of the generaActinobacillusorPasteurellaor allied organisms, however, the two new taxa are described without any formal designation. The one exception was identified asActinobacillus capsulatus, a species not previously isolated from hamster

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb03392.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Selective plating procedures were used to follow the fate of rifampicin‐resistant mutant strains of the obligately anaerobic speciesBacteroides multiacidusandSelenomonas ruminantiumafter their introduction at numbers around 107/ml into the rumen of sheep.Bacteroides multiacidusstrain F100 showed an initially rapid rate of loss (49%/h) but subsequently numbers declined more gradually approaching the limits of detection (103/ml) after 100 h. Viable cell numbers also decreasedin vitroupon addition of F100 cells to whole rumen contents, but remained stable upon addition to cell‐free rumen fluid, suggesting protozoal predation. F100 cells were able to growin vitroin whole rumen contents in the presence of an added utilizable substrate such as sorbitol, but addition of sorbitol to the rumen failed to enhance survivalin vivo. In the case ofS. ruminantium, introduced rifRstrains persisted in the rumen at levels around 106ml for at least 30 d

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb03393.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The susceptibility of 56 strains ofBranhamella catarrhalisand tenNeisseriaspp. to arsenate, silver, nickel, mercury, lead, cadmium, chromium, manganese, iron, cobalt and molybdenum was tested with an agar dilution technique. All but two strains ofB. catarrhaliswere resistant to multiple metal ions. There were not sufficient differences in susceptibility, however, to allow the development of a typing scheme based on resistograms. Heavy metal resistance inBranhamellawas unrelated to beta‐lactamase production.Neisseriaspp. were more susceptible to metal ions thanB. catarrhalisand this may form the basis of a simple diagnostic tes

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb03394.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Studies on self‐sensitivity of producer mutant vs. sensitivity of non‐producer parent and unrelated organism showed that versilin inhibited spore germination and sporulation in the self‐sensitive producer mutant, non‐producer parentAspergillus versicolorN5and the unrelated sensitiveTrichophyton rubrum. Sporulation appeared to be more sensitive than spore germination. The inhibition ofin vivosynthesis of protein was very marked, but inhibition of RNA and DNA was slight and moderate, respectively. Thus versilin was not specific in its action, but the principal sensitive site was protein synthesis, as further suggested by inhibition of polyU‐directedin vitrosynthesis of polyphenylalanine. The activation of leucine was unaffected, but the formation of leucyl‐tRNA was severely inhibited in all three strains. The differences in sensitivities between the strains were the same, whether as whole cells or as cell‐free extracts. Thus the nature of the sensitive site appeared to be identical in the self‐sensitive producer and sensitive non‐producer or u

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb03395.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The adhesion of micro‐organisms to metal surfaces has been shown to be important in the corrosion process, but the cell surface structures participating in this adhesion have not previously been identified. Evidence is presented that a bacterial substance taking part in the initial adhesion ofPseudomonas fluorescensandDesulfovibrio desulfuricans(New Jersey) to mild steel is polysaccharide in nature. It is likely that this is present in the outer membrane of the bacterial cells as lipopolysaccharid

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1989.tb03396.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY