The effect of environmental conditions on extracellular protease activity in controlled fermentations of Aspergillus niger

Braaksma, Machtelt; Smilde, Age K.; Werf, M.J. van der; Punt, Peter J.

doi:10.1099/mic.0.031062-0

Cited by 41 publications

(36 citation statements)

References 42 publications

(42 reference statements)

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“…Similar result was reflected in other studies [22,31]. Concentration of carbon and nitrogen sources in the production media significantly affects protease [34][35][36][37]. Variability in the production of protease with different percent of carbon and nitrogen sources was also observed in the present investigation.…”

Section: Discussionsupporting

confidence: 79%

Effects of Cultural Conditions on the Production of Extracellular Protease by Streptomyces albolongus and Streptomyces aburaviensis

N¹

2013

Enz Eng

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Proteolytic activity of two isolates of actinomycetes, Streptomyces albolongus and Streptomyces aburaviences was investigated on the basis of their ability to hydrolyze skimmed milk casein, egg albumin and gelatin. Both isolates were found to have potential for extracellular proteases production. Effects of culture conditions for the production of extracellular protease from S. albolongus and S. aburaviensis were determined. Highest protease yield from S. albolongus was obtained after 5 days of incubation with an initial p H 7, at static state when inoculated in medium composed of 1% glucose, 2% beef extract, 0.2% yeast extract, 0.1% KH 2 PO 4 , 0.3% K 2 HPO 4 , and trace MgSO 4 .7H 2 O. Optimum incubation conditions for S. abureviences were 4 days, with an initial medium p H 8 at shaking condition (100 rpm). S. aburaviences preferred 1.5% lactose and 1.5% tryptone as a carbon and nitrogen source. Both the isolates showed maximum protease yield at 37°C. The result of the present study might be helpful for largescale production of extracellular protease from these Streptomyces spp.

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Section: Discussionsupporting

confidence: 79%

Effects of Cultural Conditions on the Production of Extracellular Protease by Streptomyces albolongus and Streptomyces aburaviensis

N¹

2013

Enz Eng

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“…Both metabolic engineering approaches and the search for optimal cultivation conditions have long been used to improve A. niger as a production host (e.g., 14,22,41). With the availability of the A. niger genome sequence (50), systems biology tools are being developed (4,5,33) which, together with new efficient methods for constructing gene knockout mutants (43), open new possibilities for further improvement of A. niger as a cell factory.…”

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confidence: 99%

Transcriptomic Insights into the Physiology of Aspergillus niger Approaching a Specific Growth Rate of Zero

Jørgensen

Nitsche

Lamers

et al. 2010

Appl Environ Microbiol

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The physiology of filamentous fungi at growth rates approaching zero has been subject to limited study and exploitation. With the aim of uncoupling product formation from growth, we have revisited and improved the retentostat cultivation method for Aspergillus niger. A new retention device was designed allowing reliable and nearly complete cell retention even at high flow rates. Transcriptomic analysis was used to explore the potential for product formation at very low specific growth rates. The carbon-and energy-limited retentostat cultures were highly reproducible. While the specific growth rate approached zero (<0.005 h ؊1 ), the growth yield stabilized at a minimum (0.20 g of dry weight per g of maltose). The severe limitation led to asexual differentiation, and the supplied substrate was used for spore formation and secondary metabolism. Three physiologically distinct phases of the retentostat cultures were subjected to genome-wide transcriptomic analysis. The severe substrate limitation and sporulation were clearly reflected in the transcriptome. The transition from vegetative to reproductive growth was characterized by downregulation of genes encoding secreted substrate hydrolases and cell cycle genes and upregulation of many genes encoding secreted small cysteine-rich proteins and secondary metabolism genes. Transcription of known secretory pathway genes suggests that A. niger becomes adapted to secretion of small cysteine-rich proteins. The perspective is that A. niger cultures as they approach a zero growth rate can be used as a cell factory for production of secondary metabolites and cysteine-rich proteins. We propose that the improved retentostat method can be used in fundamental studies of differentiation and is applicable to filamentous fungi in general.The filamentous fungus Aspergillus niger is one of the most important microorganisms in industrial biotechnology because of its ability to produce high levels of enzymes and organic acids (6,50,57). Apart from their biotechnological importance, filamentous fungi in the Aspergillus section Nigri (the black aspergilli) represent some of the most widespread storage molds which contaminate food and feedstocks with mycotoxins (26,37,48).Both metabolic engineering approaches and the search for optimal cultivation conditions have long been used to improve A. niger as a production host (e.g., 14, 22, 41). With the availability of the A. niger genome sequence (50), systems biology tools are being developed (4, 5, 33) which, together with new efficient methods for constructing gene knockout mutants (43), open new possibilities for further improvement of A. niger as a cell factory.A major ongoing challenge for microbial production processes is to minimize the amount of biomass formed while maintaining high productivity. Solutions to uncouple product formation from biomass accumulation or growth are therefore highly desirable. However, production at zero growth is difficult to achieve when nutrients are supplied to allow formation of a desired product. Carbon-a...

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“…To prevent foaming, 1 % (v/v) antifoam (Struktol J 673) was added to the medium and, when necessary, additional antifoam was added during the cultivation. The cultivation conditions and operating procedure of the bioreactor have been described in detail previously (Braaksma et al, 2009). Cultivations were performed according to a full factorial design (total 16 conditions, and nine biological duplicates), varying the carbon source (277.5 mM glucose or 333.0 mM xylose), the nitrogen source (ammonium chloride or sodium nitrate), the nitrogen concentration [low (282.4 mM) or high (564.8 mM)] and the pH (4 or 5) (Braaksma et al, 2009).…”

Section: Methodsmentioning

confidence: 99%

“…Extracellular proteolytic activities were measured at an assay pH of 4, as described previously (Braaksma et al, 2009).…”

Section: Enzyme Assaysmentioning

confidence: 99%

Metabolomics as a tool for target identification in strain improvement: the influence of phenotype definition

et al. 2011

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For the optimization of microbial production processes, the choice of the quantitative phenotype to be optimized is crucial. For instance, for the optimization of product formation, either product concentration or productivity can be pursued, potentially resulting in different targets for strain improvement. The choice of a quantitative phenotype is highly relevant for classical improvement approaches, and even more so for modern systems biology approaches. In this study, the information content of a metabolomics dataset was determined with respect to different quantitative phenotypes related to the formation of specific products. To this end, the production of two industrially relevant products by Aspergillus niger was evaluated: (i) the enzyme glucoamylase, and (ii) the more complex product group of secreted proteases, consisting of multiple enzymes. For both products, six quantitative phenotypes associated with activity and productivity were defined, also taking into account different time points of sampling during the fermentation. Both linear and nonlinear relationships between the metabolome data and the different quantitative phenotypes were considered. The multivariate data analysis tool partial least-squares (PLS) was used to evaluate the information content of the datasets for all the different quantitative phenotypes defined. Depending on the product studied, different quantitative phenotypes were found to have the highest information content in specific metabolomics datasets. A detailed analysis of the metabolites that showed strong correlation with these quantitative phenotypes revealed that various sugar derivatives correlated with glucoamylase activity. For the reduction of protease activity, mainly as-yet-unidentified compounds correlated.

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The effect of environmental conditions on extracellular protease activity in controlled fermentations of Aspergillus niger

Cited by 41 publications

References 42 publications

Effects of Cultural Conditions on the Production of Extracellular Protease by Streptomyces albolongus and Streptomyces aburaviensis

Effects of Cultural Conditions on the Production of Extracellular Protease by Streptomyces albolongus and Streptomyces aburaviensis

Transcriptomic Insights into the Physiology of Aspergillus niger Approaching a Specific Growth Rate of Zero

Metabolomics as a tool for target identification in strain improvement: the influence of phenotype definition

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