Turbulent breakage of filamentous bacteria in mechanically agitated batch culture

Turbulent breakage of the S. erythraea filamentous actinomycete has been st udied using a 7 L laboratory scale and a 450 1 pilot scale mechanically sti rred fermenter. A model of hyphal breakage is set up based on stress cyclin g (fatigue) resulting from continuous recirculation of the mycelia through the high stress zone of the impeller. The model is based on the critical st rain energy criterion of failure reported by the authors in a previous publ ication. However, in the present study, the mycelium is assumed to have fra ctal properties and the individual hypha is assumed to behave elastically w ith a wall thickness which is assumed to increase linearly with the distanc e away from the growing tip. The experimental data obtained as part of this study and the limited results on the breakage of filamentous actinomycete from the literature are used to examine the general applicability of the mo del equation. The analysis shows reasonable agreements. (C) 1999 Elsevier S cience Ltd. All rights reserved.