최소 생산배지에 포함된 25mM 이상의 무기인(Inorganic phosphate)은 Cephalosporium acremonium의 생육은 증대시켰으나, cephalosporin C(CPC) 생산은 감소시켰다. Phosphate-starved 휴지세포계를 이용하여 균체내의 ATP, ADP와 AMP를 측정하였다. 그 결과로부터 무기인은 adenylated nucleotide의 농도의 비율로 표시되는 energy charge를 조절하여 CPC 생산성에 영향을 주는 것으로 밝혀졌다. 또한, 무기인에 의한 CPC 생합성은 repression 효과에 의한 것이 아니라 inhibition 효과에 의해 조절받는 것을 알 수 있었다.
A high concentration of inorganic phosphate (above 25 mM), which was suboptimal for vegetative growth in the minimal production medium, suppressed cephalosporin C (CPC) production in Cephalosporium acremonium. Results from the determination of intracellular concentrations of ATP, ADP and AMP with phosphate-starved resting cells indicated that phosphate exerted its effect indirectly by regulating the ratio of adenylated nucleotides, the so-called adenylated energy charge. It was also found that the type of phosphate regulation of CPC biosynthesis was not a repression effect but an inhibition effect.
