Effects of agitation intensity on mycelial morphology and protein production in chemostat cultures of recombinantAspergillus oryzae

Amanullah, Ashraf; Blair, R.; Nienow, Alvin W.; Thomas, C. R.

doi:10.1002/(sici)1097-0290(19990220)62:4<434::aid-bit6>3.0.co;2-d

Cited by 86 publications

(6 citation statements)

References 27 publications

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“…A similar off-line experiment with A. oryzae showed damage correlated by EDCF sv [64] and a similar effect was observed during bench-scale continuous [65] and fed-batch culture both with dO 2 control as before [66]. Interestingly, because the structure of the two fungi and the way that the enzymes are synthesized by A. oryzae as compared to penicillin by P. chrysogenum, with the former the production of the enzymes was found to be independent of agitation intensity or clump size in both fed-batch and continuous culture [65,66].…”

Section: Filamentous Organismssupporting

confidence: 62%

The Impact of Fluid Dynamic Stress in Stirred Bioreactors – The Scale of the Biological Entity: A Personal View

Nienow

2020

Chemie Ingenieur Technik

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From the start of industrial biotechnology, there has been a perception that biological entities are damaged by stirring, so‐called ‘shear damage'. Often, it was the soft option to explain a loss of performance when it was due to other factors, such as bubble ingestion with proteins or on scale‐up, where tip speed increased when it was due to decreased homogeneity, especially in pH. For many years, poor control and the range of analytical tools available made a more in‐depth explanation difficult; and the concepts of ‘high' and ‘low shear' impellers, now largely disproven, increased it. Here, the size of the biological entity is compared to the Kolmogorov microscale of turbulence leading to a reasonably clear picture emerging. The article starts with the author's introduction to the issue approximately 42 year ago with enzymes, conveniently also the smallest entity; and finishes with the largest, filamentous fungi.

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Section: Filamentous Organismssupporting

confidence: 62%

The Impact of Fluid Dynamic Stress in Stirred Bioreactors – The Scale of the Biological Entity: A Personal View

Nienow

2020

Chemie Ingenieur Technik

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“…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

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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.

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“…Process parameters, which affect the development of different macromorphologies range from inoculum concentration [ 33 ] and medium composition [ 31 , 34 ] over reactor shape, stirrer geometry and stirrer speed (generating different shear forces) [ 35 ], aeration rate [ 36 ] to pH and temperature [ 37 ]. It was shown that macroscopic morphologies affect protein secretion rates in aspergilli in many, but not all cases [ 36 , 38 – 47 ]. Unfortunately, the adequate macroscopic fungal morphology for given target products including organic acids, secreted proteins or secondary metabolites varies, cannot be generalized, and the advantages and disadvantages of mycelial or pellet cultivation have to be carefully adjusted for a given process and the final production scale [ 32 , 35 , 41 , 48 – 57 ].…”

Section: Introductionmentioning

confidence: 99%

Rocking Aspergillus: morphology-controlled cultivation of Aspergillus niger in a wave-mixed bioreactor for the production of secondary metabolites

et al. 2018

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BackgroundFilamentous fungi including Aspergillus niger are cell factories for the production of organic acids, proteins and bioactive compounds. Traditionally, stirred-tank reactors (STRs) are used to cultivate them under highly reproducible conditions ensuring optimum oxygen uptake and high growth rates. However, agitation via mechanical stirring causes high shear forces, thus affecting fungal physiology and macromorphologies. Two-dimensional rocking-motion wave-mixed bioreactor cultivations could offer a viable alternative to fungal cultivations in STRs, as comparable gas mass transfer is generally achievable while deploying lower friction and shear forces. The aim of this study was thus to investigate for the first time the consequences of wave-mixed cultivations on the growth, macromorphology and product formation of A. niger.ResultsWe investigated the impact of hydrodynamic conditions on A. niger cultivated at a 5 L scale in a disposable two-dimensional rocking motion bioreactor (CELL-tainer®) and a BioFlo STR (New Brunswick®), respectively. Two different A. niger strains were analysed, which produce heterologously the commercial drug enniatin B. Both strains expressed the esyn1 gene that encodes a non-ribosomal peptide synthetase ESYN under control of the inducible Tet-on system, but differed in their dependence on feeding with the precursors d-2-hydroxyvaleric acid and l-valine. Cultivations of A. niger in the CELL-tainer resulted in the formation of large pellets, which were heterogeneous in size (diameter 300–800 μm) and not observed during STR cultivations. When talcum microparticles were added, it was possible to obtain a reduced pellet size and to control pellet heterogeneity (diameter 50–150 μm). No foam formation was observed under wave-mixed cultivation conditions, which made the addition of antifoam agents needless. Overall, enniatin B titres of about 1.5–2.3 g L−1 were achieved in the CELL-tainer® system, which is about 30–50% of the titres achieved under STR conditions.ConclusionsThis is the first report studying the potential use of single-use wave-mixed reactor systems for the cultivation of A. niger. Although final enniatin yields are not competitive yet with titres achieved under STR conditions, wave-mixed cultivations open up new avenues for the cultivation of shear-sensitive mutant strains as well as high cell-density cultivations.

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Effects of agitation intensity on mycelial morphology and protein production in chemostat cultures of recombinantAspergillus oryzae

Cited by 86 publications

References 27 publications

The Impact of Fluid Dynamic Stress in Stirred Bioreactors – The Scale of the Biological Entity: A Personal View

The Impact of Fluid Dynamic Stress in Stirred Bioreactors – The Scale of the Biological Entity: A Personal View

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

Rocking Aspergillus: morphology-controlled cultivation of Aspergillus niger in a wave-mixed bioreactor for the production of secondary metabolites

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