Tailoring fungal morphology of Aspergillus niger MYA 135 by altering the hyphal morphology and the conidia adhesion capacity: biotechnological applications

Abstract

Current problems of filamentous fungi fermentations and their further successful developments as microbial cell factories are dependent on control fungal morphology. In this connection, this work explored new experimental procedures in order to quantitatively check the potential of some culture conditions to induce a determined fungal morphology by altering both hyphal morphology and conidia adhesion capacity. The capacity of environmental conditions to modify hyphal morphology was evaluated by examining the influence of some culture conditions on the cell wall lytic potential of Aspergillus niger MYA 135. The relative value of the cell wall lytic potential was determined by measuring a cell wall lytic enzyme activity such as the mycelium-bound β-N-acetyl-D-glucosaminidase (Mb-NAGase). On the other hand, the quantitative value of conidia adhesion was considered as an index of its aggregation capacity. Concerning microscopic morphology, a highly negative correlation between the hyphal growth unit length (lHGU) and the specific Mb-NAGase activity was found (r = -0.915, P < 0.001). In fact, the environment was able to induce highly branched mycelia only under those culture conditions compatible with specific Mb-NAGase values equal to or higher than 190 U gdry.wt-1. Concerning macroscopic morphology, a low conidia adhesion capacity was followed by a dispersed mycelial growth. In fact, this study showed that conidia adhesion units per ml equal to or higher than 0.50 were necessary to afford pellets formation. In addition, it was also observed that once the pellet was formed the lHGU had an important influence on its final diameter. Finally, the biotechnological significance of such results was discussed as well.

An X‐ray microtomography‐based method for detailed analysis of the three‐dimensional morphology of fungal pellets

“…These diameters of the hyphae correspond to those described in the literature (Colin, Baigorí & Pera, ; Morrison & Righelato, ; Nielsen, ; Packer et al, ). Since the average hyphal diameter was calculated on the basis of the volume of the hyphal material and the total hyphal length, our image data suggest that they are sufficiently precise to deduce biologically meaningful information.…”

Fungal pelleted reactors in wastewater treatment: Applications and perspectives

“…The inoculum size also impacts the pelleted growth [22], and an inversely proportional relationship was reported between the amount of inoculum used and pellet size [27]. Furthermore, the inoculum age has been shown to influence the final pellet diameter [28].…”

The Taming of the Shrew - Controlling the Morphology of Filamentous Eukaryotic and Prokaryotic Microorganisms

“…Fungal morphology is often a bottleneck of productivity in many industrial processes [91], and process optimisation requires the accurate characterisation of interdependencies between process parameters and performance [92]; therefore, from the very beginning of research with filamentous organisms, it has always been a goal to characterise and model morphology [93][94][95]. For the quantification of filamentous morphology, early studies relied on manual measurements of hyphal growth [96,97].…”