Autonomous growth fluctuations of the methane oxidizing bacterial strain M 102 in batch and continuous culture

Abstract

The growth rates of the methane oxidizing strain M 102 were unstable. In unlimited batch cultures they ranged from 0 to 1.4 d^-1 with most frequent values around 0.25 d^-1. The yield coefficients were between 0.1 and 1.6 mg dry weight per mg methane and varied from 1.1 to 0.4 even in a continuous culture with the limiting substrate in the gas phase. It was possible to prove intermitten release and uptake of organic compounds by the definition of a “net” yield coefficient and its theoretical boundaries. The response of the fluctuations to varying dilution frequencies and culture volumes showed analogies to controlled systems. The simultaneous variations in the age distribution and in the excretion pattern revealed the dependence of the dividing stages on a product of the young cells. The mathematical description of the findings suggests that the young cells favor division at their own disadvantage. The consequent autonomous synchronisations are the reason for the unstable growth rates of strain M 102.