Quantitative Morphological Analysis of Filamentous Microorganisms in Cocultures and Monocultures: Aspergillus terreus and Streptomyces rimosus Warfare in Bioreactors

The aim of this study was to quantitatively characterize the morphology of the filamentous microorganisms Aspergillus terreus ATCC 20542 and Streptomyces rimosus ATCC 10970, cocultivated in stirred tank bioreactors, and to characterize their mutual influence with the use of quantitative image analysis. Three distinct coculture initiation strategies were applied: preculture versus preculture, spores versus spores and preculture versus preculture with time delay for one of the species. Bioreactor cocultures were accompanied by parallel monoculture controls. The results recorded for the mono- and cocultures were compared in order to investigate the effect of cocultivation on the morphological evolution of A. terreus and S. rimosus. Morphology-related observations were also confronted with the analysis of secondary metabolism. The morphology of the two studied filamentous species strictly depended on the applied coculture initiation strategy. In the cocultures initiated by the simultaneous inoculation, S. rimosus gained domination or advance over A. terreus. The latter microorganism dominated only in these experiments in which S. rimosus was introduced with a delay.