Stachybotrys atra BP-A produces alkali-resistant and thermostable cellulases

Abstract

A cellulose-degrading fungal strain has been isolated from a rotten rag. Morphological characterization and ITS1, 5.8S and ITS2 rDNA sequencing showed that the strain is a new isolate of Stachybotrys atra. The strain secreted high cellulase activity in media supplemented with rice straw. However, cellulases were not produced in glucose-supplemented media. The crude cellulase showed the highest activity on amorphous celluloses such as carboxymethyl cellulose, while activity on crystalline celluloses such as Avicel was lower. The optimal temperature and pH for CMCase activity were 70 degrees C and pH 5 respectively, although a second peak of activity was found at pH 8. Activity was strongly inhibited by Cu(2+), Mn(2+) and Hg(2+). Analysis by SDS-PAGE, isoelectric focusing and zymography showed that the strain secretes a complex cellulase system comprising several enzymes. Most of these enzymes are alkali-resistant CMCases that remained stable at pH 9 and 65 degrees C for at least 1 h. Cellulose binding assays showed notable differences among the CMCases. While some CMCase bands did not bind Avicel, other bands bound to this polymer and were eluted either with NaCl or by boiling with SDS. Analysis by two-dimensional electrophoresis showed that the band eluted by SDS boiling contained at least 4 different polypeptides. The complex set of cellulases produced by the strain, and their activity and stability at alkaline pH and a high temperature indicate that both the isolated strain and the cellulases identified are good candidates for biotechnological applications involving cellulose modification.

Associations between Fungal Species and Water-Damaged Building Materials

“…1 and 2 and Table 3). Production of neutral cellulases has been found in these fungi (31,43) and may be a common ability of many indoor fungi that have found their niche on damp gypsum or plaster walls clad with wallpaper. A second strong association was seen between Arthrinium phaeospermum, Aureobasidium pullulans, Cladosporium herbarum, Trichoderma spp., and yeasts on different types of wood and plywood in all three analyses (PCA, CA, and PCO).…”

Expression of novel β-glucanase Cel12A from Stachybotrys atra in bacterial and fungal hosts

“…Stachybotrys atra BP-A was cultured as described (Picart et al 2008). Escherichia coli BL21(DE3) and pET28a were used as host strain and plasmid vector, respectively to express cel12A.…”

“…The production of toxins by several strains of this microorganism has probably determined the lack of in-depth studies of cellulose degradation by this fungus. We have previously identified the nontoxigenic strain S. atra BP-A, from a rotten cellulose rag, that exhibits a powerful enzyme system for the degradation of cellulosic materials (Picart et al 2008). We report here the cloning and expression of one of these enzymes, Cel12A, in the host Aspergillus niger.…”

Glycoside hydrolase inventory drives plant polysaccharide deconstruction by the extremely thermophilic bacterium Caldicellulosiruptor saccharolyticus

“…Enzyme assays were carried out after treatment with ethylenediaminetetraacetic acid (EDTA) by the addition of metal ions such as , which reduced CMCase activity to 40% and the xylanase activity to 76%, impacted enzyme function to any significant extent. This is not surprising, since this cation is known to adversely impact endoglucanases and xylanases (Bhiri et al, 2008;Gao et al, 2008;Picart et al, 2008;Zhang et al, 2007).…”