【摘要】 灰色链霉菌 No 45-706（Val^-）经36℃处理后,100%的菌落都不能形成气生菌丝,在28℃经多次传代培养,气生菌丝生长受抑制的突变株的出现最终频率为9.0%,而同时氨基酸缺陷型（Val^-）回复突变率是 6.63×10^-8。高温突变株 No 45-3（bald）经自发和NTG诱发突变,均未得到气生菌丝回复生长的菌落,但当用NTG处理菌株 No 45-706（Val^-）时,却得到了 1.26×10^-6的缬氨酸营养缺陷回复突变率。获得的98株高温突变株全部失去了生物合成链霉素的能力。 No 45菌株对青霉素敏感,但高温突变株No 45-3（bald）却对青霉素有抗性。上述结果表明灰色链霉菌中存在质粒,它控制气生菌丝的形成和链霉素的生物合成。此外,也可能和对青霉素的敏感性有关。更多还原

【Abstract】 Streptomyces griseus No. 45-706, isa valine auxotroph derived from S. gri-seus No. 45, a streptomycin producer, byUV irradiation. The ability of synthesi-zing streptomycin of No. 45-706 is about8,000 to 10,000 units per ml in shakers.When the spores of No. 45-706 wereincubated at 36℃ for 8 days, there were100% colonies being unable to formaerial mycelium. The final frequency ofaerial mycelium-negative mutants aftersuccessive transfers is about 9%. Al-though high temperature treatment at36℃ can highly induce aerial mycelium-negative mutants, yet the frequency ofvaline auxotrophic revertants is 1.51×10^-9. The aerial mycelium-negative mu-tants by high temperature treatment ofstrain No. 45-706 is 10⁸ times of that ofvaline revertants. Streptomyces griseus mutant No. 45-3 is a bald mutant as it loses the abilityto form aerial mycelium. There were nospontaneous revertants after l6 succes-sive transfers or induced revertants byNTG mutagensis. The frequency of va-line auxotrophic revertants is 1.26×10^-6.The response to NTG of strain No. 45-3 （bald） and No. 45-706 is quite dif-ferent. All the 98 mutants obtained by hightemperature treatment not only are de-fective in morphogenesis, but also losethe ability of streptomycin synthesis. Strain No. 45 was sensitive to peni-cillin originally, while mutant No. 45-3became resistant to penicillin. The above-mentioned results indicatethat plasmid（s） is present in Streptomycesgriseus strain No. 45-706. This plas-mid（s） not only control the aerial myce-lium formation but also streptomycinsynthesis, in this actinomycete. Besides,this plasmid（s） might also be involvedin the mechanism of sensitivity to penicillin.更多还原