The mechanisms of hyphal pellet formation mediated by polysaccharides, α-1,3-glucan and galactosaminogalactan, in Aspergillus species

Miyazawa, Ken; Yoshimi, Akira; Abe, Keietsu

doi:10.1186/s40694-020-00101-4

Cited by 26 publications

(27 citation statements)

References 101 publications

(183 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The morphology is influenced by different cultivation parameters including the temperature, pH value, medium composition, inoculum concentration or mechanical stress [ 17 ]. A pellet morphology is advantageous regarding the flow behavior of the culture broth, resulting in a Newtonian flow accompanied by a lower viscosity compared to media containing dispersed mycelia [ 18 ]. However, the oxygen and nutrient supply is limited within biomass pellets which can lead to cell lysis in the pellet core.…”

Section: Discussionmentioning

confidence: 99%

Acetate as substrate for l-malic acid production with Aspergillus oryzae DSM 1863

Kövilein

Umpfenbach²,

Ochsenreither³

2021

Biotechnol Biofuels

View full text Add to dashboard Cite

Background Microbial malic acid production is currently not able to compete economically with well-established chemical processes using fossil resources. The utilization of inexpensive biomass-based substrates containing acetate could decrease production costs and promote the development of microbial processes. Acetate is a by-product in lignocellulosic hydrolysates and fast pyrolysis products or can be synthesized by acetogens during syngas fermentation. For the fermentation of these substrates, a robust microorganism with a high tolerance for biomass-derived inhibitors is required. Aspergillus oryzae is a suitable candidate due to its high tolerance and broad substrate spectrum. To pave the path towards microbial malic acid production, the potential of acetate as a carbon source for A. oryzae is evaluated in this study. Results A broad acetate concentration range was tested both for growth and malic acid production with A. oryzae. Dry biomass concentration was highest for acetic acid concentrations of 40–55 g/L reaching values of about 1.1 g/L within 48 h. Morphological changes were observed depending on the acetate concentration, yielding a pellet-like morphology with low and a filamentous structure with high substrate concentrations. For malic acid production, 45 g/L acetic acid was ideal, resulting in a product concentration of 8.44 ± 0.42 g/L after 192 h. The addition of 5–15 g/L glucose to acetate medium proved beneficial by lowering the time point of maximum productivity and increasing malic acid yield. The side product spectrum of cultures with acetate, glucose, and cultures containing both substrates was compared, showing differences especially in the amount of oxalic, succinic, and citric acid produced. Furthermore, the presence of CaCO3, a pH regulator used for malate production with glucose, was found to be crucial also for malic acid production with acetate. Conclusions This study evaluates relevant aspects of malic acid production with A. oryzae using acetate as carbon source and demonstrates that it is a suitable substrate for biomass formation and acid synthesis. The insights provided here will be useful to further microbial malic acid production using renewable substrates.

show abstract

Section: Discussionmentioning

confidence: 99%

Acetate as substrate for l-malic acid production with Aspergillus oryzae DSM 1863

Kövilein

Umpfenbach²,

Ochsenreither³

2021

Biotechnol Biofuels

View full text Add to dashboard Cite

show abstract

“…Cell-wall polysaccharides are thought to be synthesized on the plasma membrane after the secretory vesicles containing polysaccharide synthases have been exported to the hyphal tip (Riquelme, 2013). On the basis of our previous findings (Miyazawa et al, 2020), we hypothesize the process of alkali-soluble glucan biosynthesis of A. nidulans to be as follows:…”

Section: Discussionmentioning

confidence: 85%

“…fumigatus , A. nidulans agsB and its orthologues are clustered with two α-amylase-encoding genes ( amyD and amyG in A . nidulans ) (He et al, 2014;Yoshimi et al, 2017;Miyazawa et al, 2020). The amyG gene encodes an intracellular α-amylase and is crucial for α-1,3-glucan synthesis (He et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

A glycosylphosphatidylinositol-anchored α-amylase encoded by amyD contributes to a decrease in the molecular mass of cell wall α-1,3-glucan in Aspergillus nidulans

Miyazawa

Yamashita

Takeuchi

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Abstractα-1,3-Glucan is one of the main polysaccharides in the cell wall of Aspergillus nidulans. We previously revealed that it plays a role in hyphal aggregation in liquid culture, and that its molecular mass (MM) in an agsA-overexpressing (agsAOE) strain was larger than that in an agsB-overexpressing (agsBOE) strain. The mechanism that regulates the MM of α-1,3-glucan is poorly understood. Although the gene amyD, which encodes glycosyl-phosphatidylinositol (GPI)-anchored α-amylase (AmyD), is involved in the biosynthesis of α-1,3-glucan in A. nidulans, how it regulates this biosynthesis remains unclear. Here we constructed strains with disrupted amyD (ΔamyD) or overexpressed amyD (amyDOE) in the genetic background of the ABPU1 (wild-type), agsAOE, or agsBOE strain, and characterized the chemical structure of α-1,3-glucans in the cell wall of each strain, focusing on their MM. The MM of α-1,3-glucan from the agsBOE amyDOE strain was smaller than that in the parental agsBOE strain. In addition, the MM of α-1,3-glucan from the agsAOE ΔamyD strain was greater than that in the agsAOE strain. These results suggest that AmyD is involved in decreasing the MM of α-1,3-glucan. We also found that the C-terminal GPI-anchoring region is important for these functions.

show abstract

“…Formation of mycelium pellets is one of the hurdles that can negatively affect the fermentation efficacy of industrial fungi for biomaterial productions [ 20 , 55 ]. It was previously considered that fungal mycelium pellets was formed by the winding of hyphae to form aggregated and compact pellets [ 56 ].…”

Section: Discussionmentioning

confidence: 99%

“…Similar to the bacterium EPS Pel [16], GAG can also mediate biofilm formation to increase the resistance of A. fumigatus against antifungal drugs [17,18]. In addition, it has been found that the cell wall GAG as well as α-1,3-glucan can mediate the aggregation of A. oryzae hyphae to form mycelium pellets in liquid culture [19,20]. Production of the EPSs containing α-1,4 linked GalNAc and GalN has also been reported in a few non-Aspergillus ascomycete fungi such as Neurospora crassa, Penicillium frequentans and Paecilomyces sp.…”

Section: Introductionmentioning

confidence: 99%

Conservative production of galactosaminogalactan in Metarhizium is responsible for appressorium mucilage production and topical infection of insect hosts

et al. 2021

View full text Add to dashboard Cite

The exopolysaccharide galactosaminogalactan (GAG) has been well characterized in Aspergilli, especially the human pathogen Aspergillus fumigatus. It has been found that a five-gene cluster is responsible for GAG biosynthesis in Aspergilli to mediate fungal adherence, biofilm formation, immunosuppression or induction of host immune defences. Herein, we report the presence of the conserved GAG biosynthetic gene cluster in the insect pathogenic fungus Metarhizium robertsii to mediate either similar or unique biological functions. Deletion of the gene cluster disabled fungal ability to produce GAG on germ tubes, mycelia and appressoria. Relative to the wild type strain, null mutant was impaired in topical infection but not injection of insect hosts. We found that GAG production by Metarhizium is partially acetylated and could mediate fungal adherence to hydrophobic insect cuticles, biofilm formation, and penetration of insect cuticles. In particular, it was first confirmed that this exopolymer is responsible for the formation of appressorium mucilage, the essential extracellular matrix formed along with the infection structure differentiation to mediate cell attachment and expression of cuticle degrading enzymes. In contrast to its production during A. fumigatus invasive growth, GAG is not produced on the Metarhizium cells harvested from insect hemocoels; however, the polymer can glue germ tubes into aggregates to form mycelium pellets in liquid culture. The results of this study unravel the biosynthesis and unique function of GAG in a fungal system apart from the aspergilli species.

show abstract

The mechanisms of hyphal pellet formation mediated by polysaccharides, α-1,3-glucan and galactosaminogalactan, in Aspergillus species

Cited by 26 publications

References 101 publications

Acetate as substrate for l-malic acid production with Aspergillus oryzae DSM 1863

Acetate as substrate for l-malic acid production with Aspergillus oryzae DSM 1863

A glycosylphosphatidylinositol-anchored α-amylase encoded by amyD contributes to a decrease in the molecular mass of cell wall α-1,3-glucan in Aspergillus nidulans

Conservative production of galactosaminogalactan in Metarhizium is responsible for appressorium mucilage production and topical infection of insect hosts

Contact Info

Product

Resources

About