A. C. Hayward

A comparison of five methods for assaying bacterial hydrophobicity

Five methods for assaying bacterial surface hydrophobicity, namely, bacterial adherence to hydrocarbons, salt aggregation, hydrophobic interaction chromatography, adhesion to polystyrene and latex particle agglutination were used to compare the hydrophobic surface properties of Escherichia coli, Acinetobacter calcoaceticus, Staphylococcus aureus and Streptococcus mitis. Two strains of A. calcoaceticus, including RAG-1, gave strong positive results by all five methods. S. mitis gave weak or negative results by all methods. The results for the other bacteria varied with the method. We conclude that reliance on one method for such tests is inadequate.

Surface Appendages Similar to Fimbriae (Pili) on Pseudomonas Species

SUMMARY: Twenty-two strains of Pseudomonas, representing 15 species, were examined by electron microscopy, utilizing the techniques of negative contrast staining and to a lesser extent shadowing and ultrathin sectioning. Fimbria-like appendages were found on cells of 12 strains, representing 8 species. Polar, fimbria-like filaments were observed on Pseudomonas aeruginosa, P. acidovorans, P. testosteroni, P. maltophilia, P. alcaligenes and P. solanacearum. Peritrichous filaments were found on P. multivorans and P. fragi.

The sheathed flagellum of Pseudomonas stizolobii.

SUMMARY: Organisms of two strains of Pseudomonas stizolobii possessed one polar flagellum of unusual thickness. Negative-contrast staining and ultrathin sectioning indicated that the flagella are sheathed and are comparable in structure to the sheathed flagella described in Vibrio and Bdellovibrio. In some instances, flagella displayed sheath and core structure after negative constrast staining. Distal ‘tubules’ and ‘knobs’ apparently consisting entirely of sheath material were also seen. The thickness of the sheath, which in section consisted of an outer dense component and an inner lighter component, was similar to that of the outer double track membrane of the cell wall.

Use of ribotyping and random amplified polymorphic DNA to differentiate isolates of Burkholderia andropogonis.

Aims:u2002The aim of this study was to determine the genetic diversity among isolates of Burkholderia andropogonis from various host plant species and geographic locations.

Application of multidishes to the characterization of proteolytic psychrotrophs from raw milk

Abstract This paper describes a procedure in which 24-well multidishes and an eight-channel pipette were used in physiological tests to characterize proteolytic, psychorotrophic and, mainly fluorescent, pseudomonads which had been isolated from refrigerated raw milk. Some of these tests have not been duplicated by any of the currently available commercial identification systems. Of the 41 biochemical tests examined, 32 could be performed in multidishes. Multidishes could be used in tests to determine carbon source utilization (27 substrates), growth on MacConkey and cetrimide agars, pigment production on King B agar, gelatin hydrolysis and levan production. Since four tests could be simultaneously inoculated, with less than 2.0 ml of medium per test, the properties of a large number of strains could be rapidly and economically determined. Differences between multidish and conventional test results in the 37°C growth test depended upon whether strains were grown on agar or in liquid medium. Hydrolyses of DNA, butterfat and egg yolk and the dissolution of crystals on tyrosine agar were more easily read when tests were performed in petri dishes than in multidishes. False positive results were obtained for melanin production on tyrosine agar. Arginine dihydrolase, Simmons citrate and urease tests could not be performed in multidishes since the diffusion of an alkaline product, presumably ammonia, through the headspace above wells resulted in false positive reactions.