In aerobic static broth cultures grown at 37", salmonellas of genotype Fim( I)+, i.e. bearing type-I (mannose-sensitive, haemagglutinating) fimbriae, formed a surface pellicle consisting of densely packed bacteria shortly after the cessation of logarithmic growth at about 6 hr, and then, during the next 24 hr, underwent a large secondary phase of growth. Salmonellas of genotype Fim(a)+, i.e. bearing type-2 (non-haemagglutinating) fimbriae, and most Fim-(non-fimbriate) salmonellas did not form a pellicle and gave only slight post-logarithmic growth; after 24-72 hr the amount of their growth, i.e. bacterial concentration estimated turbidimetrically, was only one-third to one-half that of comparable type-1 fimbriate bacteria. Fimstrains of Salmonella typhimurium differed from most other Fim-salmonellas by forming a pellicle and undergoing an associated secondary phase of growth, but they gave these effects 24-48 hr later than did the Fim( I)+ strains. A pellicle was not formed by any organism either in static cultures incubated anaerobically or in cultures aerated by continuous shaking, and in these two sets of conditions the course and amount of growth were the same for the Fim(1)f as for the Fim-bacteria. It is concluded that the large secondary phase of growth shown by the Fim(I)+ bacteria in aerobic static broth results from the free availability of atmospheric oxygen to the bacteria growing in the pellicle.The presence of 0.2 yo (w/v) of the haemagglutination-inhibiting sugar, a-methylmannoside, which was not utilized within 6 days, delayed by more than 24 hr the formation of a pellicle and the onset of the secondary phase of growth in aerobic static cultures of the Fim(z)+ strain LT2 of Salmonella typhimurium. Another haemagglutination-inhibiting sugar, D-mannose, was utilized within 12 hr and delayed pellicle formation by only 2-3 hr in cultures of strain L T~, but it caused a prolonged (> 24 hr) delay in pellicle formation in cultures of two non-mannose-utilizing mutants of strain L T~. D-glucose and L-sorbose, which do not inhibit haemagglutination, did not delay pellicle formation. These findings, together with the failure of Fim(2)+ bacteria to form a pellicle, suggest that the property of type-1 hbriae that promotes early pellicle formation is the same as that responsible for the mannose-sensitive haemagglutinating activity.
Bacterial pathogens of Greenshell mussel (GSM) larvae can cause batch losses during hatchery production. Twenty-two isolates were screened using a larval bioassay. Two strains were identified as potential pathogens. Phenotypic identification of these strains revealed two non-reactive Gram-negative, oxidase positive rods. Sequencing of the 16S rRNA gene identified Vibrio splendidus and a V. coralliilyticus/neptunius-like isolate as pathogens of GSM larvae, with an ability to cause 83% and 75% larval mortality in vitro, respectively, at a concentration of 10(2) CFU mL(-1). Histopathology indicated that the route of infection was via the digestive system. Using healthy larvae as target hosts, Koch's postulates were confirmed for the two isolates. This is the first report on pathogens of GSM larvae.
The storage and survival of 97 species (276 strains) of bacteria at – 70° to – 80°C was investigated. Each strain was subcultured at regular intervals over a period of 6–40 months in order to check its viability. All strains were viable after the latest subculture except strains of Neisseria gonorrhoeae which proved non‐viable when tested after 12 months. The method proved most useful for storing stock cultures which required frequent and regular accessing.
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