[Conditions for Legionella pneumophila cultivation that affect cytotoxin production].
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Experiments in CHO cell cultures have demonstrated the cytotoxic action of culture filtrates obtained after growing L. pneumophilia strain Philadelphia I, serogroup 1, in a liquid culture medium. This cytotoxic activity has been found to differ in its character from that described in earlier works. The dynamics of the accumulation of cytotoxin in the culture medium has been studied, and the work aimed at the determination of the limits of some cultivation parameters, within which the maximum toxin formation is observed, has been carried out.Keywords:
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Experiments in CHO cell cultures have demonstrated the cytotoxic action of culture filtrates obtained after growing L. pneumophilia strain Philadelphia I, serogroup 1, in a liquid culture medium. This cytotoxic activity has been found to differ in its character from that described in earlier works. The dynamics of the accumulation of cytotoxin in the culture medium has been studied, and the work aimed at the determination of the limits of some cultivation parameters, within which the maximum toxin formation is observed, has been carried out.
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Botulinum C2 toxin, which has enterotoxic as well as lethal activities, induced roundings of tissue-cultured cells of eight different mammalian cell lines. The morphological changes in all of the cell lines were accompanied by degeneration and lysis of cells. The results indicate that C2 toxin has cytopathic activity and causes cytotoxic effect on mammalian cell lines.
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These studies show that Clostridium botulinum types C and D cultures can be cured of their prophages and converted to either type C or D depending on the specific phage used. Strains of types C and D were cured of their prophages and simultaneously ceased to produce their dominant toxins designated as C 1 and D, respectively. Cured nontoxigenic cultures derived from type C strain 162 were sensitive to the phages from the toxigenic type C strain 162 and type D strain South African. When cured nontoxigenic cultures derived from strain 162 were infected with the tox + phages from the 162 strain of type C and the South African strain of type D, they then produced toxin neutralized by types C and D antisera, respectively. Cured nontoxigenic cultures isolated from the type D South African strain were only sensitive to the parent phage, and, when reinfected with the tox + phage, they produced toxin neutralized by type D antiserum. Type C strain 153 and type D strain 1873, when cured of their respective prophages, also ceased to produce toxins C 1 and D, but, unlike strain 162 and the South African strain, they continued to produce a toxin designated as C 2 . When the cured cultures from strains 153 and 1873 were infected with the tox + phage from type D strain 1873, the cultures simultaneously produced toxin that was neutralized by type D antiserum. When these cured cultures were infected with the tox + phage from type C strain 153, the cultures produced toxin that was neutralized by type C antiserum. These studies with the four strains of C. botulinum confirm that the toxigenicity of types C and D strains requires the continued participation of tox + phages. Evidence is presented that types C and D cultures may arise from a common nontoxigenic strain.
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Objective To improve the production procedure for inactivated vaccine against Aeromonas hydrophila J-1 strain and increase the culture efficiency.Methods J-1 strain was cultured in modified and toxin-producing media by mechanical stirring under ventilating condition,based on which the time for fermentation was determined,and the culture effets of the two media were compared.The culture liquid of J-1 strain was inactivated in shake-flask and in inactivation tank respectively,and the inactivation effects by formaldehyde at various concentrations were compared.Results The growth level of J-1 strain reached a peak value 12 ～ 24 h after culture in fermentation tank by mechanical stirring.The mean viable count in culture liquid in modified medium was 216 × 108 CFU / ml,which increased by 111.7% as compared with that in toxin-producing medium(102 × 108 CFU / ml),and reached 300 × 108 CFU / ml at most.However,the virulence of culture liquid in modified medium was slightly higher than that in toxin-producing medium.The treatment with 0.3% formalin at 37℃ for 24 h inactivated the culture liquid completely,while the residual formalin content in prepared inactivated vaccine met the relevant quality standard.Conclusion Modified medium was superior to toxin-producing medium in culture of J-1 strain,and the time for culture of A.hydrophia by mechanical stirring in fermentation tank was only a half of that by original procedure.
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The effects of storage of stool specimens at various temperatures on recovery of Clostridium difficile and detection of cytotoxin were determined. At 0°C cytotoxin appeared stable, while at 5°C and 25°C there were decreases in toxin titres of 1.4 and 1.7 logs respectively after 2 days, followed by a stabilising of titres. C. difficile could be cultured for a minimum of 4 days after storage at 5°C and 25°C, and for up to 10 days if an enrichment broth was used. Five different tissue culture cell lines were compared for susceptibility to C. difficile cytotoxin. VERO cells were most susceptible followed by WI-38, Y-1, CHO and HEp2.
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Journal Article Detection of a novel campylobacter cytotoxin Get access A. Lee, A. Lee Department of Applied Biology and Biotechnology, RMIT University, Melbourne and Search for other works by this author on: Oxford Academic Google Scholar S.C. Smith, S.C. Smith School of Health Sciences, Deakin University, Burwood, Victoria, Australia Search for other works by this author on: Oxford Academic Google Scholar P.J. Coloe P.J. Coloe Department of Applied Biology and Biotechnology, RMIT University, Melbourne and Search for other works by this author on: Oxford Academic Google Scholar Journal of Applied Microbiology, Volume 89, Issue 4, 1 October 2000, Pages 719–725, https://doi.org/10.1046/j.1365-2672.2000.01175.x Published: 01 October 2000 Article history Received: 29 March 2000 Revision received: 07 June 2000 Accepted: 19 June 2000 Published: 01 October 2000
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Summary Most toxigenic strains of Clostridium difficile produce both toxin A and toxin B. The toxin produced by C. difficile strain 8864 was characterised and compared with those produced by C. difficile strain 10463. Toxin A was not detected by immunoassay in cultures from strain 8864 and all the cytotoxic activity produced by this strain was neutralised by antiserum to toxin B. Toxin B from strain 8864 was purified and compared with toxin B from strain 10463. The size of the purified subunits of toxin B from strain 8864 differed slightly from those of strain 10463 and there were small immunological differences. The effect on fibroblast cells was more like that of C. sordellii cytotoxin than of toxin B from strain 10463. These results suggest that C. difficile strain 8864 produces a modified toxin B and does not produce toxin A.
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ABSTRACT Spent culture supernatant from early-stationary-phase Mycobacterium tuberculosis H37Ra cultures increased the viability of bacilli from aged cultures of this strain and allowed small inocula to initiate growth in liquid culture. The resuscitation factor was acid labile and heat stable, with a mass of less than 1,375 Da.
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