Hydrodynamic, physiological, and morphological characteristics of Fusarium moniliforme in geometrically dissimilar stirred bioreactors

Abstract

The influence of two mixing geometries (at the same scale) with different flow energy distributions on the performance of the gibberellic acid fermentation and on the morphology of the producing fungus Fusarium moniliforme was investigated. Fermentations were performed using a turbine mixing system (TMS) and a counterflow mixing system (CMS), which were high and low power number mixing systems, respectively. Different agitator speed rate profiles were maintained to obtain equal specific power inputs to both mixing systems. Substantial differences in morphology and productivity of F. moniliforme were found. To investigate the causes of these differences, local values and spectra of the kinetic energy of flow fluctuations were measured during the fermentations using a stirring intensity measuring device (SIMD) and a frequency spectrum analyzer. Biomass and gibberellic acid concentrations were found to be higher in the TMS, where the energy distribution was less even, and Vi/here the main part of the energy was at small frequencies (large eddies). An automated image analysis method was used for quantitative characterization of F. moniliforme freely dispersed mycelia and clump morphology. A higher proportion of clumped mycelia with clumps of larger area, perimeter, and roughness was observed in the TMS. A correlation between the morphology and productivity was found, and TMS favored the development of more productive mycelia with longer and thinner hyphae. Introduced power was not a good parameter to characterize different impellers, even at a given scale.

Excess turbulence as a cause of turbohypobiosis in cultivation of microorganisms

“…In conditions where the intensity of local turbulence is high but insufficient for the mechanical disruption of the cultivated cells, changes in the cell morphology were often observed [2,56,62,[66][67][68][69][70][71][72][73][74][75][76]. Simultaneously with morphological adjustment, the physiological character, namely, the productivity of metabolite synthesis [66,67,69,72,73,76], biological activity [70,74,77] and enzyme activity [71] also changed.…”

“…Simultaneously with morphological adjustment, the physiological character, namely, the productivity of metabolite synthesis [66,67,69,72,73,76], biological activity [70,74,77] and enzyme activity [71] also changed. Hence, these morphological changes may be regarded to be not a simple result of the mechanical deformation of cells, but a reaction to the changes in cultivation conditions.…”

Mixing Intensity Studies by Simd using Dissimilar Stirrers. Case Study: Production of Fusicoccin by the Fungus Fusicoccum Amygdali Del.

“…Since the sensitivity of a particular fungal culture to mixing and flow distribution conditions varied due to different mycelial morphology as well as broth viscosity and the physico-chemical influences, the performance of the fermentations analysed and the kinetic energy e distribution patterns at the agitator speed rates under study varied substantially. Our results (7) show that essential information about the mixing influence can be obtained by spectral analysis of energy e, which can be done by connecting the SIMD-Fl analog output with the input of any spectral analyser or any spectral analysing IBM PC board. The results obtained show that SIMD-Fl may be used as a tool for mixing studies in microbial fermentation broths.…”

Monitoring of Submerged Bioprocesses

“…A correlation between mycelial morphology (dispersed and clumped) and productivity has been reported for gibberellic acid fermentation by Fusarium moniliforme (Priede et al, 1995). It was also reported that a turbine mixing system favored the development of more productive mycelia with longer and thinner hyphae, when compared with a counterflow mixing system (Priede et al, 1995).…”