Microbial Production of Squalene by a Nicotinic Acid-Resistant Mutant Derived from Fusarium sp. No. 5-128B

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A nicotinic acid-resistant mutant, designated NA201,was obtained from Fusarium sp. no. 5-128B by treatment with ultraviolet light. This mutant strain could grow in the presence of up to 500mM nicotinic acid in the culture medium, although the parent strain could not grow at concentrations of nicotinic acid above 200 mM. The NA201 strain exhibited morphological mutations, neither forming aerial hyphae nor secreting a red-brown pigment. However, it retained the resistance to kabicidin at 25mg/l^<-1> of the parent strain. The mutant NA201 cells contained high levels of squalene and low levels of ergosterol, about 53 times higher and five to six times lower, respcetively, than those of the parent strain under standard culture conditions. The volumetric oxygen transfer coefficient (Kd) affected the level of squalene in the mutant cells. The Kd for the maximum production of squalene by the mutant was 24 mmol O_2/l^<-1>h^<-1>atm^<-1> and the level of squalene in the mutan cells was 26mg (g cell)^<-1> on a dry weight basis. The greatest accumulation of squalene by the NA201 strain, corresponding to 323 mg per liter of culture medium and 35 mg (g cell)^<-1> on a dry weight basis, was achieved in a culture in which the Kd was changed from a high to a low value on the third day, with the simultaneous addition of 3% glucose(w/v).
社団法人日本生物工学会の論文
1994-04-25