SUMMARYSuccessful isolation of azotobacter phages from soil samples was accomplished by using a m o d i f i e d Burk's nitrogen-free medium with sucrose as the carbon source.The natural azotobacter flora in the soil samples served as the enrichment strains and the medium was not further enriched by the addition of laboratory cultures of the bacteria. Phage titres as high as 5 . 5~1 0~ plaque-forming units/ml. were obtained when the indicator strain for phage assays was Axrdobacter vindandii 0. On the basis of plaque morphology, nine phage isolates were obtained and purified by standard techniques. The plaques formed by the phages consisted of a central clear area surrounded by a halo and ranged from 1 to 7 m. in diameter. Antiphage sera were produced in rabbits against a previously isolated phage and the new isolates; on the basis of cross-neutralization experiments with homologous and heterologous antisera, the 10 phages were placed into four major serological groups.Groups I and I1 contained four phages each, and groups I11 and IV contained one phage each. The degree of serological relatedness among the phages within groups I and I1 was investigated. A survey of 48 azotobacter strains showed that 11 out of 12 A. vhelandii strains and 14 out of 25 A. chroococmm strains showed plaque formation by one or more of the phages. Strains of A. agilis, A . mucrocytogms, A. hwigne and A. indim were not lysed by the phages. The value of the present series of phages in the classification of the genus Azotobacter was discussed.
Fiock, Mary
A. (Fort Detrick, Frederick, Md.),
Allen Yarinsky, and James T. Duff
. Studies on immunity to toxins of
Clostridium botulinum
. VII. Purification and detoxification of trypsin-activated type E toxin. J. Bacteriol.
82:
66–71. 1961.—A procedure was described for production, purification, and conversion to toxoid of the
Clostridium botulinum
type E trypsin-treated toxin. A medium containing 1.5% trypticase, 0.5% yeast extract, 0.075% cysteine hydrochloride, and 1.0% glucose consistently yielded activated culture toxicities of 300,000 mouse intraperitoneal
ld
50
/ml. Purification of the toxin was accomplished by precipitation with ammonium sulfate, extraction with calcium chloride, and reprecipitation with ethanol in the cold. The resulting partially purified toxin had a specific activity of 45,000,000
ld
50
/mg nitrogen. Purified toxins were converted to toxoid by incubation with formalin and adsorbed on aluminum phosphate. Good immune responses were obtained to the toxoids in mice, guinea pigs, and rabbits.
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