- Volume 21, Issue 1, 1959

SUMMARY: A study of phytopathogenic pseudomonads was begun, but it was found that they could not easily be differentiated from the commonly occurring soil- and water-inhabiting fluorescent pseudomonads. A collection of 169 isolates, including 24 named cultures from various collections, was studied. Both old and new kinds of diagnostic characters, cytological, physiological and biochemical, were investigated under standard conditions. Recordings were made at frequent intervals during a 28-day incubation period. Each character was investigated at least three times during a period of at least five years in order to assess its stability.

A clear differentiation between Pseudomonas hydrophila (NCTC 7810) and P. icthyosmia (NCTC 8049) and the rest of the collection was apparent; these two isolates belong to the genus Aeromonas Kluyver & van Niel. The use of the vibrio- static pteridine derivative 0/129 revealed a close relationship between them and Vibrio icthyodermis PL 1.

Of the 169 isolates (including at least 20 named species) 165 had 26 common definable and stable characters; these are offered for an extended definition of the genus Psetidomonas. A further 43 characteristics were not common to all 165 isolates. No two of these characters were correlated. One isolate had 42/43 positive characters and one had only 4, and there was a very great range of variation. Among 58 selected isolates there were 21 small groups of identical isolates, but the largest number in any group was 5; the remaining 107 isolates each had a different combination of the 43 characters. Even 10 fluorescent isolates, originally obtained from a single plating of 1 loopful of river water, showed 9 different combinations of characters.

A small group of 5 isolates appeared to conform with Pseudomonas aeruginosa as defined by Haynes (1951) and Gaby (1955) but many fluorescens-type isolates were closely related when considered on the basis of all the characters investigated. Several of the named phytophathogens showed a close relationship, or apparent identity, with soil and water isolates; many phytophathogens, however, had a conspicuous number of negative characters, suggesting loss of adaptability in a more selective environment.

The 134 soil- and water-type isolates had 11 positive characters, and 9 others almost always positive. On this basis, and adopting the view that all these characters merit equal emphasis (see Tanner, 1918; Sneath, 1957a, b) it is thought that further divisions into subgroups (species?) are not justified, and that these characters should be used to describe accurately P. fluorescens Migula 1894. A definition of this species is suggested.

SUMMARY: Two protozoa, Ochromonas malhamensis and Tetrahymena pyriformis, were used to study the mode of action and side effects of three antihistamines: diphenhydramine, tripelennamine and pheniramine. The mode of action was studied by inhibition analysis and the side effects by motility tests. The use of these methods as preliminary screening procedures for new chemotherapeutic agents is discussed.

SUMMARY: Fimbriae were found in 125 of 154 non-motile Klebsiella strains examined by electron-microscope in serial aerobic broth cultures. Fimbriate strains occurred in each of the capsule serotypes 1–72 and mostly showed the biochemical reactions of saprophytic Klebsiella aerogenes. The fimbriae were clearly distinguishable from the capsules and occurred also in non-capsulate mutants. Most fimbriate strains showed evidence of varying reversibly between a fimbriate and a non-fimbriate phase. The proportion of bacilli with fimbriae was greatest in broth cultures and was decreased, though never eliminated, by serial cultivation on nutrient agar. All 29 permanently non-fimbriate strains belonged to serotypes 1–6 and showed biochemical reactions common in pathogenic K. pneumoniae, K. ozaenae and K. rhinoscleromatis strains (anaerogenic, methyl-red positive, non-citrate utilizing or nonlactose fermenting). They differed from the fimbriate strains in growing less abundantly and usually in failing to form a pellicle on broth.

All the fimbriate strains, but none of the non-fimbriate, showed one or other or both of two kinds of adhesive property: one attributed to an ‘MS adhesion’ susceptible to inhibition by d-mannose and associated with a thick variety of fimbriae; the other due to an ‘MR adhesin’, resistant to mannose and associated with thinner fimbriae. Bacilli with MS adhesin rapidly adhered to red blood cells of the guinea-pig and other animals, except the ox, to leucocytes and to intestinal epithelial cells, including those of ox, to Candida albicans cells, to the mycelium of Aspergillus niger and other moulds, and to plant root-hairs. Bacilli with only the MR adhesin did not adhere to untreated red cells, leucocytes or ‘smooth’ yeasts, but adhered rapidly to ox and other red cells treated with tannic acid, red-cell stromata heated at 70° or 100°, fungus mycelium and plant root-hairs. Bacilli of many fimbriate strains and one non-capsulate non-fimbriate strain adhered to glass and cellulose.