Effect of branch frequency inAspergillus oryzae on protein secretion and culture viscosity

Bocking, Sharon P.; Wiebe, Marilyn G.; Robson, Geoffrey D.; Hansen, Kim Toft; Christiansen, Lars; Trinci, Anthony P. J.

doi:10.1002/(sici)1097-0290(19991220)65:6<638::aid-bit4>3.0.co;2-k

Cited by 73 publications

(55 citation statements)

References 45 publications

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“…The morphology of Aspergillus, filamentous growth forms and/or the shape and size of pelleted growth forms as well as the branching frequency, is influenced by many factors including specific strain properties [22] but also environmental factors such as spore numbers in the inoculum or type of inoculum [23][24][25], medium composition [23,[26][27][28], dissolved oxygen concentration [29][30][31], pH [23,32], temperature [23,27], reactor type and scale [27,33], and power input [23,25,26,28,29,[33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Agitation effects on morphology and protein productive fractions of filamentous and pelleted growth forms of recombinant Aspergillus niger

El‐Enshasy

Kleine

Rinas

2006

Process Biochemistry

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Recombinant Aspergillus niger genetically engineered to produce glucose oxidase using the constitutive gpdA promoter and the glucoamylase signal sequence for secretion was grown in batch cultures at agitation speeds of 200 -800 rpm covering the industrial relevant power input range of 0.1 -5 W kg -1 . The growth morphology ranged from large pellets with an average diameter of 1500 µm at low power input up to micropellets embedded in a filamentous network at high power input. A correlation of agitation intensity with growth morphology and glucose oxidase production revealed an increase of the protein production capability with the change of the growth morphology from pelleted to filamentous growth forms. However, the exposure to higher shear stress with increasing power input also resulted in lower biomass yields as well as increased transient formation of polyol (xylitol) and higher final concentrations of oxalic acid. The highest specific production rates were found in young filamentous growth forms at high power input. Although intermediate agitation intensity leading to small pellets became more favorable during prolonged cultivation. An acridine orange staining procedure discriminating between RNA rich (red) and RNA poor regions (green) of the fungal biomass proved that active protein production is restricted to filamentous growth forms and the outer layer of fungal pellets. A correlation between the RNA rich fraction of the biomass determined by image analysis and the productivity is shown.

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Section: Introductionmentioning

confidence: 99%

Agitation effects on morphology and protein productive fractions of filamentous and pelleted growth forms of recombinant Aspergillus niger

El‐Enshasy

Kleine

Rinas

2006

Process Biochemistry

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“…The relationship between the mycelial morphology and the rheological properties of the cultivation medium has been the subject of a number of studies (2,15,19,25). The hyphal length per branch (length of the hyphal growth unit [l HGU ]) affects the overall morphology (34); a low l HGU has been associated with the formation of clumps smaller than those formed at a high l HGU (2).…”

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confidence: 99%

“…The hyphal length per branch (length of the hyphal growth unit [l HGU ]) affects the overall morphology (34); a low l HGU has been associated with the formation of clumps smaller than those formed at a high l HGU (2). Studies of the fungal cell wall suggest that chitin synthesis is an important factor in determining the hyphal morphology.…”

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confidence: 99%

Metabolic Engineering of the Morphology of Aspergillus oryzae by Altering Chitin Synthesis

Müller

McIntyre

Hansen

et al. 2002

Appl Environ Microbiol

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Morphology and ␣-amylase production during submerged cultivation were examined in a wild-type strain (A1560) and in strains of Aspergillus oryzae in which chitin synthase B (chsB) and chitin synthesis myosin A (csmA) have been disrupted (ChsB/G and CM101). In a flowthrough cell, the growth of submerged hyphal elements was studied online, making it possible to examine the growth kinetics of the three strains. The average tip extension rates of the CM101 and ChsB/G strains were 25 and 88% lower, respectively, than that of the wild type. The branching intensity in the CM101 strain was 25% lower than that in the wild type, whereas that in the ChsB/G strain was 188% higher. During batch cultivation, inseparable clumps were formed in the wild-type strain, while no or fewer large inseparable clumps existed in the cultivations of the ChsB/G and CM101 strains. The ␣-amylase productivity was not significantly different in the three strains. A strain in which the transcription of chsB could be controlled by the nitrogen source-regulated promoter niiA (NiiA1) was examined during chemostat cultivation, and it was found that the branching intensity could be regulated by regulating the promoter, signifying an important role for chsB in branching. However, the pattern of branching responded very slowly to the change in transcription, and increased branching did not affect ␣-amylase productivity. ␣-Amylase residing in the cell wall was stained by immunofluorescence, and the relationship between tip number and enzyme secretion is discussed.Filamentous fungi, such as Aspergillus oryzae, are widely used for industrial enzyme production, since they are able to secrete large amounts of proteins (e.g., amylases, proteases, phytases, and lipases) into the medium. Filamentous fungi grow by hyphal extension and branching through processes that are regulated in a way that is still not completely understood. During submerged cultivation, the growing hyphal elements tend to entangle, and this affects the rheology of the cultivation medium and the mixing characteristics in an undesirable fashion. This results in poor mixing and poor mass transfer of the substrate, and it makes the morphologies of filamentous fungi an obvious, yet unanswered, challenge in process optimization. Recently, however, there have been major advances in the tools available for metabolic engineering of aspergilli (reviewed by McIntyre et al. [17]), such as developments in genomics, the increased number of suitable transformation vectors, and powerful image analysis tools that enable rapid quantification of the fungal morphology. This has made metabolic engineering of the morphology for process optimization possible.Metabolic engineering of morphology requires detailed knowledge of the relationships among productivity, growth, and morphology. The morphologies of filamentous organisms can be classified into macroscopic and microscopic morphologies (21), and techniques for analyzing morphology on both of these levels have advanced rapidly during the last decade (reviewed...

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“…Chitosan has been reported to induce higher synthesis of cell wall-associated enzymes, phenolic compounds, amino acids and some secondary metabolites in fungi [31,32]. Laccase secretion in filamentous fungi can be enhanced by lots of factors, which range from availability of saprophytic nutrients to morphological changes [17,33]. Chitosan could have facilitated increased synthesis of intracellular laccase and its efflux, thereby increasing the laccase activity in the medium.…”

Section: Resultsmentioning

confidence: 99%

Chitosan multiple addition enhances laccase production from Trametes versicolor

Adekunle

Wang

et al. 2015

Bioprocess Biosyst Eng

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Chitosan multiple addition strategy was developed to improve laccase production from Trametes versicolor cultures. The optimized multiple addition strategy was carried out by two-time addition of 0.1 g L -1 chitosan to a 2-day-old culture media, with 24-h interval between the treatments. Under these conditions, laccase activity of 644.9 U l -1 was achieved on the seventh day and laccase production was improved by 93.5 % higher than the control. Chitosan treatment increased reactive oxygen species generation and extracellular protein concentration in the treated mycelia. In contrast, the inducer inhibited the mycelia growth. The result of the quantitative reverse transcription polymerase chain reaction showed that the copy number of the laccase gene transcript increased by 16.7-fold in the treated mycelia relative to the control. This study provides insight into some of the intrinsic metabolic processes involved in the upregulation of laccase production in the presence of chitosan inducer in fungal culture.

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Effect of branch frequency inAspergillus oryzae on protein secretion and culture viscosity

Cited by 73 publications

References 45 publications

Agitation effects on morphology and protein productive fractions of filamentous and pelleted growth forms of recombinant Aspergillus niger

Agitation effects on morphology and protein productive fractions of filamentous and pelleted growth forms of recombinant Aspergillus niger

Metabolic Engineering of the Morphology of Aspergillus oryzae by Altering Chitin Synthesis

Chitosan multiple addition enhances laccase production from Trametes versicolor

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