Expression, purification, crystallization and preliminary X-ray diffraction analysis of Aspergillus terreus endo-β-1,4-glucanase from glycoside hydrolase family 12

Matrix Discriminant Analysis Evidenced Surface-Lithium as an Important Factor to Increase the Hydrolytic Saccharification of Sugarcane Bagasse

Statistical evidence pointing to the very soft change in the ionic composition on the surface of the sugar cane bagasse is crucial to improve yields of sugars by hydrolytic saccharification. Removal of Li⁺ by pretreatments exposing -OH sites was the most important factor related to the increase of saccharification yields using enzyme cocktails. Steam Explosion and Microwave:H₂SO₄ pretreatments produced unrelated structural changes, but similar ionic distribution patterns. Both increased the saccharification yield 1.74-fold. NaOH produced structural changes related to Steam Explosion, but released surface-bounded Li⁺ obtaining 2.04-fold more reducing sugars than the control. In turn, the higher amounts in relative concentration and periodic structures of Li⁺ on the surface observed in the control or after the pretreatment with Ethanol:DMSO:Ammonium Oxalate, blocked -OH and O^- available for ionic sputtering. These changes correlated to 1.90-fold decrease in saccharification yields. Li⁺ was an activator in solution, but its presence and distribution pattern on the substrate was prejudicial to the saccharification. Apparently, it acts as a phase-dependent modulator of enzyme activity. Therefore, no correlations were found between structural changes and the efficiency of the enzymatic cocktail used. However, there were correlations between the Li⁺ distribution patterns and the enzymatic activities that should to be shown.

Marine Fungi: Biotechnological Perspectives from Deep-Hypersaline Anoxic Basins

Deep-sea hypersaline anoxic basins (DHABs) are one of the most hostile environments on Earth. Even though DHABs have hypersaline conditions, anoxia and high hydrostatic pressure, they host incredible microbial biodiversity. Among eukaryotes inhabiting these systems, recent studies demonstrated that fungi are a quantitatively relevant component. Here, fungi can benefit from the accumulation of large amounts of organic material. Marine fungi are also known to produce bioactive molecules. In particular, halophilic and halotolerant fungi are a reservoir of enzymes and secondary metabolites with valuable applications in industrial, pharmaceutical, and environmental biotechnology. Here we report that among the fungal taxa identified from the Mediterranean and Red Sea DHABs, halotolerant halophilic species belonging to the genera Aspergillus and Penicillium can be used or screened for enzymes and bioactive molecules. Fungi living in DHABs can extend our knowledge about the limits of life, and the discovery of new species and molecules from these environments can have high biotechnological potential.

Cloning, heterologous expression and biochemical characterization of a non-specific endoglucanase family 12 from Aspergillus terreus NIH2624

The cellulases from Glycoside Hydrolyses family 12 (GH12) play an important role in cellulose degradation and plant cell wall deconstruction being widely used in a number of bioindustrial processes. Aiming to contribute toward better comprehension of these class of the enzymes, here we describe a high-yield secretion of a endoglucanase GH12 from Aspegillus terreus (AtGH12), which was cloned and expressed in Aspergillus nidulans strain A773. The purified protein was used for complete biochemical and functional characterization. The optimal temperature and pH of the enzyme were 55°C and 5.0 respectively, which has high activity against β-glucan and xyloglucan and also is active toward glucomannan and CMC. The enzyme retained activity up to 60°C. AtGH12 is strongly inhibited by Cu²⁺, Fe²⁺, Cd²⁺, Mn²⁺, Ca²⁺, Zn²⁺ and EDTA, whereas K⁺, Tween, Cs⁺, DMSO, Triton X-100 and Mg²⁺ enhanced the enzyme activity. Furthermore, SAXS data reveal that the enzyme has a globular shape and CD analysis demonstrated a prevalence of a β-strand structure corroborating with typical β-sheets fold commonly found for other endoglucanases from GH12 family.