Effect of oxygen enrichment on morphology, growth, and heterologous protein production in chemostat cultures ofAspergillus niger B1-D

Wongwicharn, Aporn; McNeil, Brian; Harvey, Linda M.

doi:10.1002/(sici)1097-0290(19991120)65:4<416::aid-bit6>3.0.co;2-z

Cited by 64 publications

(16 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is generally accepted that protein secretion occurs mainly at the hyphal apex [11]–[14]. Some studies suggested a positive correlation between the amount of hyphal branches and protein secretion yields [13], [15]–[17], whereas other reports demonstrated no correlation [9], [18]. Therefore, it is still a matter of debate whether a hyperbranching production strain would considerably improve protein secretion rates.…”

Section: Introductionmentioning

confidence: 99%

The Transcriptomic Signature of RacA Activation and Inactivation Provides New Insights into the Morphogenetic Network of Aspergillus niger

et al. 2013

View full text Add to dashboard Cite

RacA is the main Rho GTPase in Aspergillus niger regulating polarity maintenance via controlling actin dynamics. Both deletion and dominant activation of RacA (RacG18V) provoke an actin localization defect and thereby loss of polarized tip extension, resulting in frequent dichotomous branching in the ΔracA strain and an apolar growing phenotype for RacG18V. In the current study the transcriptomics and physiological consequences of these morphological changes were investigated and compared with the data of the morphogenetic network model for the dichotomous branching mutant ramosa-1. This integrated approach revealed that polar tip growth is most likely orchestrated by the concerted activities of phospholipid signaling, sphingolipid signaling, TORC2 signaling, calcium signaling and CWI signaling pathways. The transcriptomic signatures and the reconstructed network model for all three morphology mutants (ΔracA, RacG18V, ramosa-1) imply that these pathways become integrated to bring about different physiological adaptations including changes in sterol, zinc and amino acid metabolism and changes in ion transport and protein trafficking. Finally, the fate of exocytotic (SncA) and endocytotic (AbpA, SlaB) markers in the dichotomous branching mutant ΔracA was followed, demonstrating that hyperbranching does not per se result in increased protein secretion.

show abstract

Section: Introductionmentioning

confidence: 99%

The Transcriptomic Signature of RacA Activation and Inactivation Provides New Insights into the Morphogenetic Network of Aspergillus niger

et al. 2013

View full text Add to dashboard Cite

show abstract

“…Wongwicharn et al (1999) found heterologous enzyme secretion in A. niger to correlate with hyphal tip number as oxygen concentration was increased. Furthermore, they were able to show a correlation between the active area of the biomass and protein secretion [54]. Amanullah et al (1999), in contrast found no direct effect of fungal morphology on protein secretion while researching the influence of agitation intensity [55].…”

Section: Resultsmentioning

confidence: 99%

Morphology engineering - Osmolality and its effect on Aspergillus niger morphology and productivity

2011

View full text Add to dashboard Cite

BackgroundThe filamentous fungus Aspergillus niger is a widely used strain in a broad range of industrial processes from food to pharmaceutical industry. One of the most intriguing and often uncontrollable characteristics of this filamentous organism is its complex morphology, ranging from dense spherical pellets to viscous mycelia depending on culture conditions. Optimal productivity correlates strongly with a specific morphological form, thus making high demands on process control.ResultsIn about 50 2L stirred tank cultivations the influence of osmolality on A. niger morphology and productivity was investigated. The specific productivity of fructofuranosidase producing strain A. niger SKAn 1015 could be increased notably from 0.5 to 9 U mg-1 h-1 around eighteen fold, by increasing the culture broth osmolality by addition of sodium chloride. The specific productivity of glucoamylase producing strain A. niger AB1.13, could be elevated using the same procedure. An optimal producing osmolality was shown to exist well over the standard osmolality at about 3.2 osmol kg-1 depending on the strain. Fungal morphology of all cultivations was examined by microscope and characterized by digital image analysis. Particle shape parameters were combined to a dimensionless Morphology number, which enabled a comprehensive characterization of fungal morphology correlating closely with productivity. A novel method for determination of germination time in submerged cultivations by laser diffraction, introduced in this study, revealed a decelerated germination process with increasing osmolality.ConclusionsThrough the introduction of the versatile Morphology number, this study provides the means for a desirable characterization of fungal morphology and demonstrates its relation to productivity. Furthermore, osmolality as a fairly new parameter in process engineering is introduced and found to affect fungal morphology and productivity. Osmolality might provide an auspicious and reliable approach to increase the productivity in industrial processes. Because of the predictable behavior fungal morphology showed in dependence of osmolality, a customization of morphology for process needs seems feasible.

show abstract

“…Oxygen enrichment has been previously shown to increase µ and DCW in cultures of A. niger 19 and has been used in several industrial processes to increase product formation202122.…”

Section: Discussionmentioning

confidence: 99%

“…The spore concentration was determined by use of a haemocytometer and a spore inoculum of 2–4 mL from a 10 5 spores/mL stock solution was used. The medium used for the cultivation of the innoculum (preculture) was described by Wongwicharn et al 19 with 50 g/l glucose as carbon and energy source.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Inactivating alternative NADH dehydrogenases: enhancing fungal bioprocesses by improving growth and biomass yield?

Voulgaris

O’Donnell

Harvey

et al. 2012

Sci Rep

Self Cite

View full text Add to dashboard Cite

Debate still surrounds the physiological roles of the alternative respiratory enzymes found in many fungi and plants. It has been proposed that alternative NADH:ubiquinone oxidoreductases (NADH dehydrogenases) may protect against oxidative stress, conversely, elevated activity of these enzymes has been linked to senescence. Here we show that inhibition of these enzymes in a fungal protein expression system (Aspergillus niger) leads to significantly enhanced specific growth rate, substrate uptake, carbon dioxide evolution, higher protein content, and more efficient use of substrates. These findings are consistent with a protective role of the NADH dehydrogenases against oxidative stress, thus, when electron flow via these enzymes is blocked, flux through the main respiratory pathway rises, leading to enhanced ATP generation. We anticipate that our findings will stimulate further studies in fungal and plant cultures leading to significant improvements in these expression systems, and to deeper insights into the cellular roles of alternative respiration.

show abstract

Effect of oxygen enrichment on morphology, growth, and heterologous protein production in chemostat cultures ofAspergillus niger B1-D

Cited by 64 publications

References 43 publications

The Transcriptomic Signature of RacA Activation and Inactivation Provides New Insights into the Morphogenetic Network of Aspergillus niger

The Transcriptomic Signature of RacA Activation and Inactivation Provides New Insights into the Morphogenetic Network of Aspergillus niger

Morphology engineering - Osmolality and its effect on Aspergillus niger morphology and productivity

Inactivating alternative NADH dehydrogenases: enhancing fungal bioprocesses by improving growth and biomass yield?

Contact Info

Product

Resources

About