Kinetic studies on the aggregation of Aspergillus niger conidia

Abstract

Morphology has a crucial effect on productivity and the supply of substrate for cultures of filamentous fungi. However, cultivation parameters leading to the desired morphology are often chosen empirically as the mechanisms governing the processes involved are usually unknown. For coagulating microorganisms like Aspergillus niger the morphological development is considered to start with the aggregation of conidia right after inoculation. To elucidate the mechanism of this process, kinetic studies were carried out using an in-line particle size analyzer. Based on the data obtained from these experiments a model for conidial aggregation is proposed in this article. It consists of two separate aggregation steps. The first one takes place immediately after inoculation, but only leads to a small decrease of total particle concentration. Most suspended conidia aggregate after a second aggregation step triggered by germination and hyphal growth. Aggregation velocity of this second phase is linearly dependent on the particle growth rate. B 2004 Wiley Periodicals, Inc.

Review of Microalgae Harvesting via Co-Pelletization with Filamentous Fungus

“…With q tip (μm h ) being a constant tip growth rate of n tip, the total hyphal length growth can be determined [52]:…”

“…An essential relationship between tip growth and hyphal branching is described as hyphal growth unit (HGU), which is the average length of each tip in a mycelium [52]:…”

“…In coagulating pellet formation, the spores usually aggregate in the early stage of cultivation and pellets are formed out of these aggregates. This type of pellet formation can include Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae, and the basidiomycete fungus Phanerochaete chrysosporium [45,50,52]. For example, Aspergillus niger, a common filamentous fungus that has been studied extensively, gives a clear image of the microscopic morphology that is related to the formation of the pellets [52].…”

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“…In general, there is a strong connection between productivity and morphology of growing filamentous fungi (Grimm et al, 2005b). Previous studies have shown that the early stage spore aggregation is an important step in the morphological development of A. niger (Elmayergi et al, 1973;Galbraith and Smith, 1969;Grimm et al, 2004).…”

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