Dependence of nitrogen- and phosphorus-regulation of beta-lactam antibiotic production by Streptomyces clavuligerus on aeration level.

Interference with beta-lactam production in Streptomyces clavuligerus by ammonium and phosphate ions, normally observed with optimum levels of aeration, was eliminated by restriction of the air supply. Under such a restriction, ammonium slightly stimulated and phosphate markedly stimulated beta-lactam antibiotic production. These are rare examples of 'regulation reversal' by an environmental modification.