Environmental signals triggering methylenomycin production by Streptomyces coelicolor A3(2)

Methylenomycin production by Streptomyces coelicolor A3(2) may be triggered by either of two environmental signals: alanine growth-rate- limiting conditions and/or an acidic pH shock. The production of this SCP1- encoded antibiotic was studied by using batch and chemostat cultures. Batch cultures indicated a role for both nutritional status and culture pH in its regulation. Steady-state methylenomycin production and transcription of an mmy gene under alanine but not glucose growth-rate-limiting conditions was demonstrated in chemostat culture. Transient mmy expression and methylenomycin production occurred following an acidic pH shock. This stimulation of methylenomycin production occurred independently of the nutritional status of the growth environment. Antibiotic production was partially suppressed under alanine compared with glucose growth-rate-limiting conditions following the acidic pH shock. A low specific growth rate was a prerequisite for both steady-state and transient production of methylenomycin.