Khan A A, Srivastava R, Sinha V B, Srivastava B S
J Gen Microbiol. 1985 Oct;131(10):2653-7. doi: 10.1099/00221287-131-10-2653.
Vibrio cholerae strain 569B Inaba harbouring P plasmid produced less toxin than the parent strain. To examine the effect of plasmid loss on toxin production, temperature-sensitive (ts) mutants of P, unable to replicate at 42 degrees C, were isolated. One ts plasmid was unstable at 42 degrees C and its loss yielded a cured strain that resumed a normal level of toxin biosynthesis characteristic of the plasmid-free parent strain. Toxin production was again suppressed in the cured strain after reacquisition of P plasmid. This suggested a role for plasmid-borne genes in the regulation of toxin biosynthesis. A mutant of strain 569B Inaba that produced mutant toxin was isolated by transfer of P and V plasmids. The mutant toxin was similar to choleragenoid because it did not give rise to symptoms of cholera but induced antitoxin immunity in rabbits.
携带P质粒的霍乱弧菌569B稻叶型菌株产生的毒素比亲本菌株少。为了研究质粒丢失对毒素产生的影响，分离出了在42℃无法复制的P质粒温度敏感（ts）突变体。一种ts质粒在42℃不稳定，其丢失产生了一个治愈菌株，该菌株恢复了无质粒亲本菌株特有的正常毒素生物合成水平。在重新获得P质粒后，治愈菌株中的毒素产生再次受到抑制。这表明质粒携带的基因在毒素生物合成调控中发挥作用。通过转移P质粒和V质粒，分离出了产生突变毒素的569B稻叶型菌株突变体。该突变毒素类似于类霍乱原，因为它不会引发霍乱症状，但能在兔子体内诱导抗毒素免疫。
