Influence of carbon source on α-amylase production by Aspergillus oryzae

Carlsen, Morten; Nielsen, Jens

doi:10.1007/s002530100772

Cited by 79 publications

(64 citation statements)

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“…Freeze-dried spores were used to inoculate rice cultures by the method of Carlsen (5). Six to 8 days after inoculation, the rice grains were covered with green or white spores.…”

Section: Methodsmentioning

confidence: 99%

“…Filtered cultivation liquid was diluted 10 times with 0.1 g of bovine serum albumin liter Ϫ1 and 0.1 g of CaCl 2 liter Ϫ1 and frozen after being sampled. Before analysis, the mixture was thawed and the extracellular ␣-amylase activity was determined by a modified Boehringer Mannheim method using a Cobas Mira analyzer (Roche Diagnostics) as previously described (7). The unit of ␣-amylase activity is fungal ␣-amylase units (FAU) per milliliter (1 FAU is the amount of ␣-amylase which at 37°C hydrolyzes 5.26 g of starch h Ϫ1 [12]).…”

Section: Methodsmentioning

confidence: 99%

“…Within the flowthrough cell, fungal spores were attached to the surface with poly-D-lysine, substrate flow was started, and images of the growing hyphal elements were acquired. Images of the developing hyphal elements were acquired every 15 (5). The design and preparation of the flowthrough cell was described previously (29).…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

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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“…Freeze-dried spores were used to inoculate rice cultures by the method of Carlsen (5). Six to 8 days after inoculation, the rice grains were covered with green or white spores.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

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

Müller

McIntyre

Hansen

et al. 2002

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…Aspergilli are a group of filamentous fungi that play an important role as cell factories for the production of organic acids, for example citric acid by Aspergillus niger (Kubicek & Röhr, 1986), of enzymes, for example a-amylase by Aspergillus oryzae (Carlsen & Nielsen, 2001), and of polyketides, for example statins by Aspergillus terreus (Manzoni & Rollini, 2002). Besides their industrial importance, aspergilli can act as pathogens for humans and animals, being responsible for diseases that range from allergy-type illness to life-threatening generalized infections, most commonly caused by Aspergillus fumigatus and Aspergillus flavus, but also Aspergillus nidulans and others (http:// www.Aspergillus.man.ac.uk).…”

Section: Introductionmentioning

confidence: 99%

CreA influences the metabolic fluxes of Aspergillus nidulans during growth on glucose and xylose

et al. 2005

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The physiological phenotype of Aspergillus nidulans was investigated for different genetic and environmental conditions of glucose repression through the quantification of in vivo fluxes in the central carbon metabolism using 13 C-metabolic-flux analysis. The particular focus was the role of the carbon repressor CreA, which is the major regulatory protein mediating carbon repression in many fungal species, in the primary metabolism of A. nidulans. Batch cultivations were performed with a reference strain and a deletion mutant strain (creAD4) using [1-13 C]glucose as carbon source. The mutant strain was also grown on a mixture of [1-13 C]glucose and unlabelled xylose. Fractional enrichment data were measured by gas chromatography-mass spectrometry. A model describing the central metabolism of A. nidulans was used in combination with fractional enrichment data, and measurements of extracellular rates and biomass composition for the estimation of the in vivo metabolic fluxes. The creA-mutant strain showed a lower maximum specific growth rate than the reference strain when grown on glucose (0?11 and 0?25 h "1 , respectively), whereas the specific growth rate of the mutant strain grown on the glucose/xylose mixture was identical to that on glucose (0?11 h "1 ). Different patterns and increased levels of extracellular polyols were observed both upon deletion of the creA gene and upon addition of xylose to the growth medium of the mutant strain. Concerning metabolic fluxes, the major change observed in the flux distribution of A. nidulans upon deletion of the creA gene was a 20 % decrease in the flux through the oxidative part of the pentose-phosphate pathway. Addition of xylose to the growth medium of the mutant resulted in an increase of about 40 % in the activity of the oxidative part of the pentose-phosphate pathway, as well as decreases in the fluxes through the Embden-Meyerhof-Parnas pathway and the tricarboxylic acid cycle (in the range of 20-30 %). The derepression of key pathways leads to alterations in the demands for cofactors, thereby imposing changes in the central metabolism due to the coupling of the many different reactions via the redox and energy metabolism of the cells.

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“…The amount of carbon dioxide produced in respiration can then be calculated as the total amount of carbon dioxide formed minus the amount of ethanol produced. For the calculation of the carbon recovery, fungal biomass composition of CH 1.72 O 0.55 N 0.17 with an ash content of 7.5% (w/w) was used (Carlsen and Nielsen 2001).…”

Section: Calculationsmentioning

confidence: 99%

Lactic acid production from xylose by the fungus Rhizopus oryzae

Maas

Bakker

Eggink

et al. 2006

Appl Microbiol Biotechnol

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Lignocellulosic biomass is considered nowadays to be an economically attractive carbohydrate feedstock for large-scale fermentation of bulk chemicals such as lactic acid. The filamentous fungus Rhizopus oryzae is able to grow in mineral medium with glucose as sole carbon source and to produce optically pure L(+)-lactic acid. Less is known about the conversion by R. oryzae of pentose sugars such as xylose, which is abundantly present in lignocellulosic hydrolysates. This paper describes the conversion of xylose in synthetic media into lactic acid by ten R. oryzae strains resulting in yields between 0.41 and 0.71 g g −1

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Influence of carbon source on α-amylase production by Aspergillus oryzae

Cited by 79 publications

References 0 publications

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

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

CreA influences the metabolic fluxes of Aspergillus nidulans during growth on glucose and xylose

Lactic acid production from xylose by the fungus Rhizopus oryzae

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