A. niger transformations Protoplasts were prepared

from A. niger UU-A049.1 as described and transformed using polyethylene glycol [21]. Transformation of A. niger UU-A049.1 with ppoA and ppoD disruption constructs created transformants to ArginineB prototrophy with the catalytic domain of the corresponding gene product deleted. Three independent Aspergillus niger transformations did not result in the isolation of a ppoC selleck products disruptant and we were therefore not able to analyze this gene disruption. Transformants were purified by repeated streaking of conidia. Gene replacement and ectopic integration of the argB marker gene were checked by PCR and Southern analysis using internal fragments as probes. Probe construction and Inhibitor Library Southern analysis

Constructs of complete genes of ppoA and ppoD were digested with EcoRV and SphI, respectively, yielding internal probes for the encoding region of the catalytic domain. Fragments were separated on an 0.8% agarose gel, isolated and randomly labeled with [α-32P]dCTP. This resulted in 1082 and 1146 bp fragments for ppoA and a 1241 bp fragment for ppoD. Chromosomal DNA of A. niger transformants was digested with the appropriate restriction enzymes. Hybridization with radioactive probes was done as described, except that washing of the filters was done at 65°C [22]. Positive transformants, lacking the signals from the internal probes on the Southernblot, were selected and used for further characterization. Phenotypic characterization of A. niger

transformants Characterization of A. niger transformants was performed on solid minimal medium containing 1% glucose and supplemented with or without 1 M NaCl and/or selleck chemicals 0.01% H2O2 at 30°C and 42°C. Spots of 10000, 1000, 100 and 10 conidia were pipetted on each plate and incubated. Strains A. niger 49.1 and A. niger N402 were used as wild type. Spore production studies were carried out on plates containing 25 mL solid minimal medium and 1% glucose [3]. For each plate a 5 mL top layer of cool melted 0.6% agar minimal medium and 1% Temsirolimus purchase glucose containing 107 conidia of the appropriate strain was added. In some cases 1.5% methanol or 1.5% methanol and 10 μg/mL linoleic acid were added to both agar layers. Cultures were incubated at 30°C. Cores of 16 mm diameter were removed from each plates and homogenized for 1 min in 3 mL sterile water supplemented with 0.01% Tween-80 to facilitate release of the hydrophobic conidia. Spores were counted by using a haemacytometer. A. niger microarray analysis A. niger N402 was grown at 30°C as sandwiched cultures [23] in minimal medium [15] with 25 mM maltose or 25 mM D-xylose as carbon source. Zonal mycelial samples from 3 sandwich cultures were combined and used for RNA analysis. Mycelium was ground using a microdismembrator and RNA was extracted using TRIzol reagent (Invitrogen, Carlsbad, CA) according to the instructions of the manufacturer. RNA was purified using Nucleospin RNA clean up (Macherey-Nagel GmbH, Düren, Germany).