Isolation and characterization of two specific regulatory Aspergillus niger mutants shows antagonistic regulation of arabinan and xylan metabolism

Groot, M.J.; Vondervoort, Peter J. I. van de; Vries, Ronald P. de; vanKuyk, Patricia A.; Ruijter, George J. G.; Visser, Jaap

doi:10.1099/mic.0.25993-0

Cited by 47 publications

(54 citation statements)

References 26 publications

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“…Since xyl1 is dispensable for growth on L-arabinitol, this effect must therefore be a regulatory one. De Groot et al (8) reported that the induction of arabinan-degrading enzymes by L-arabinitol in A. niger depends on the function of the products of the araA and araB genes, which positively regulate their expression and also that of the genes encoding the L-arabinose catabolic pathway. Unfortunately, the respective genes have not yet been identified.…”

Section: Discussionmentioning

confidence: 99%

“…(for a review, see reference 43). However, XlnR has been reported not to regulate arabinan and L-arabinose metabolism in the Aspergilli (8). In analogy, Stricker et al (42) reported that a xyr1 knock out in H. jecorina did not affect growth of the fungus on L-arabinose and also L-arabinose reductase activities.…”

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confidence: 93%

“…de Groot et al (8) identified two loci (araA and araB) in A. niger, which seem to contain positive-acting genes involved in the expression of arabinanase-encoding genes and the genes encoding the enzymes of the L-arabinose catabolic pathway. However, the genes corresponding to these two loci have not been cloned yet.…”

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confidence: 99%

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Molecular Regulation of Arabinan and l -Arabinose Metabolism in Hypocrea jecorina ( Trichoderma reesei )

et al. 2009

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Hypocrea jecorina (anamorph: Trichoderma reesei) can grow on plant arabinans by the aid of secreted arabinan-degrading enzymes. This growth on arabinan and its degradation product L-arabinose requires the operation of the aldose reductase XYL1 and the L-arabinitol dehydrogenase LAD1. Growth on arabinan and L-arabinose is also severely affected in a strain deficient in the general cellulase and hemicellulase regulator XYR1, but this impairment can be overcome by constitutive expression of the xyl1 encoding the aldose reductase. An inspection of the genome of H. jecorina reveals four genes capable of degrading arabinan, i.e., the ␣-L-arabinofuranosidase encoding genes abf1, abf2, and abf3 and also bxl1, which encodes a ␤-xylosidase with a separate ␣-L-arabinofuranosidase domain and activity but no endo-arabinanase. Transcriptional analysis reveals that in the parent strain QM9414 the expression of all of these genes is induced by L-arabinose and to a lesser extent by L-arabinitol and absent on D-glucose. Induction by L-arabinitol, however, is strongly enhanced in a ⌬lad1 strain lacking L-arabinitol dehydrogenase activity and severely impaired in an aldose reductase (⌬xyl1) strain, suggesting a cross talk between L-arabinitol and the aldose reductase XYL1 in an ␣-L-arabinofuranosidase gene expression. Strains bearing a knockout in the cellulase regulator xyr1 do not show any induction of abf2 and bxl1, and this phenotype cannot be reverted by constitutive expression of xyl1. The loss of function of xyr1 has also a slight effect on the expression of abf1 and abf3. We conclude that the expression of the four ␣-Larabinofuranosidases of H. jecorina for growth on arabinan requires an early pathway intermediate (L-arabinitol or L-arabinose), the first enzyme of the pathway XYL1, and in the case of abf2 and bxl1 also the function of the cellulase regulator XYR1.The recently reinitiated interest in second-generation biofuel production (i.e., from renewable plant material whose use does not compete with use for food and feed production) also led to a renaissance in cellulase and hemicellulase production by the ascomycete Hypocrea jecorina (anamorph Trichoderma reesei), the current best producer of these enzymes (27). The efficient use of these enzymes for plant biomass hydrolysis, however, is still limited by several factors, including incomplete knowledge of regulation of production of these enzymes.The L-arabinose polymer arabinan is another polysaccharide found in plant cell wall heteropolysaccharides as a side chain of pectin (9), and L-arabinose is particularly abundant in the form of glucuronoarabinoxylans in monocotyledon primary cell walls of Commelinoid flowery plants and as arabinoxylans in cereal grains, where it can mount up to 25 to 30% (4, 11). H. jecorina is also able to degrade arabinan to L-arabinose by an arabinanolytic system. To date, two arabinofuranosidases have been characterized: an ␣-L-arabinofuranosidase (ABF1) (26) and a ␤-xylosidase which has a separate ␣ L-arabinofuranosidase domain and activity...

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Section: Discussionmentioning

confidence: 99%

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Molecular Regulation of Arabinan and l -Arabinose Metabolism in Hypocrea jecorina ( Trichoderma reesei )

et al. 2009

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“…During fermentation of molasses, glucose is consumed first, followed by fructose and sucrose (Rincon et al 2001). Catabolic repression by glucose and fructose (de Groot et al 2003) does not permit the formation of extracellular invertases, which converts sucrose into glucose and fructose, which are then sequentially consumed by the organism.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and thermodynamics of ethanol production by a thermotolerant mutant of Saccharomyces cerevisiae in a microprocessor-controlled bioreactor

Rajoka

Ferhan

Khalid

2005

Lett Appl Microbiol

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Aims: The present investigation deals with the development of thermotolerant mutant strain of yeast for studying enhanced productivity of ethanol from molasses in a fully controlled bioreactor. Methods and Results: The parental culture of Saccharomyces cerevisiae ATCC 26602 was mutated using UV treatment. A single thermotolerant mutant was isolated after extensive screening and optimization, and grown on molasses medium in liquid cultures. The mutant was 1AE45-fold improved than its wild parent with respect to ethanol productivity (7AE2 g l )1 h )1 ), product yield (0AE44 g ethanol g )1 substrate utilized) and specific ethanol yield (19AE0 g ethanol g )1 cells). The improved ethanol productivity was directly correlated with titres of intracellular and extracellular invertase activities. The mutant supported higher volumetric and product yield of ethanol, significantly (P £ 0AE05) higher than the parental and other strains. The mutated cultures produced 1AE8-and 2AE6-fold more extracellular and intracellular invertase productivity, respectively, than that produced by its wild parent at 40°C. Thermodynamic studies revealed that the cell system exerted protection against thermal inactivation during formation of products. Conclusions: A mutant derivative of Sacchromyces cerevisiae with improved productivity of ethanol and invertases has been obtained, which showed concomitant improvement in thermostability of endogenous metabolism for formation of both ethanol and invertases. Significance and Impact of the Study: The results of the present study are of commercial value as the mutant can be used for ethanol production in parts of Pakistan where the temperature may go up to 40°C in April. Ethanol product yield coefficient and volumetric productivity, revealed the hyper-productivity of ethanol from molasses at 40°C, which is not appropriate for wild organism.

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“…In this study, we investigated whether the mutant selection system used by de Groot et al (2003) could be applied to identify functions involved in xylitol metabolism. We show that this selection system was capable of selecting a new mutant affected in xylitol-mediated repression, and detailed investigation of a xylitol-derepressed mutant shows it to be severely hampered in xylitol transport.…”

Section: Introductionmentioning

confidence: 99%

Selection and characterisation of a xylitol-derepressed Aspergillus niger mutant that is apparently impaired in xylitol transport

Vondervoort

Groot

Ruijter

et al. 2006

Appl Microbiol Biotechnol

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Aspergillus niger is known for its biotechnological applications, such as the use of xylanase enzyme for the degradation of hemicellulose. Depending on culture conditions, several polyols may also be accumulated, such as xylitol during D-xylose oxidation. Also during industrial fermentation of xylose for the production of fuel ethanol by recombinant yeast, xylitol is a by-product. We studied xylitol metabolism by isolating mutants that have impaired xylitol-mediated repression. Genetic and biochemical characterisation revealed that one of these mutants was affected not only in xylitol-mediated carbon repression, but also had impaired xylitol transport.

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Isolation and characterization of two specific regulatory Aspergillus niger mutants shows antagonistic regulation of arabinan and xylan metabolism

Cited by 47 publications

References 26 publications

Molecular Regulation of Arabinan and l -Arabinose Metabolism in Hypocrea jecorina ( Trichoderma reesei )

Molecular Regulation of Arabinan and l -Arabinose Metabolism in Hypocrea jecorina ( Trichoderma reesei )

Kinetics and thermodynamics of ethanol production by a thermotolerant mutant of Saccharomyces cerevisiae in a microprocessor-controlled bioreactor

Selection and characterisation of a xylitol-derepressed Aspergillus niger mutant that is apparently impaired in xylitol transport

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