[Stability of Shigella flexneri attenuated strain 2A 77 ADE- RIF-r after cultivation in a fermenter and lyophilization].
The method for the cultivation of S. flexneri attenuated strain 2a 77 ade- rifr in a fermenter with the use of casein fermentative broth containing 200-250 mg% of amino nitrogen has been developed. No changes in the properties of the initial strain have been found after its cultivation in a fermenter or after the lyophilization of the cultures grown in a fermenter. After cultivation in casein fermentative broth with 100 mg% of amino nitrogen the presence of S-R dissociation has been established, the S colonies having the properties of the initial strain. The reversion of the R colonies to prototrophism in adenine and differences in the level of their resistance to rifampicin are observed. The study of the plasmid profile of the initial strain and its ade+ revertants has revealed the disappearance of plasmids with a molecular weight of 140 MD in these revertants. All clones under study (ade+ and ade-) show negative results in the keratoconjunctival test. The conditions of cultivation and the causes of reversion are discussed.
Nenkov
P
P
Bratoeva
M
M
Vitanov
T
T
Marinova
S
S
Denchev
V
V
D005285:Fermentation; D005612:Freeze Drying; D010957:Plasmids; D012763:Shigella flexneri / Q000254:growth & development*
Issledovaniia stabil'nosti attenuirovannogo shtamma Shigella flexneri 2A 77 ADE- RIF-r posle kul'tivirovaniia v reaktore i liofilizatsii.