Characterization of a thermostable endoglucanase produced by Isoptericola variabilis sp. IDAH9

Characterization, structural, and evolutionary analysis of an extremophilic GH5 endoglucanase from Bacillus sp. G131: Insights from ancestral sequence reconstruction

Nature has developed extremozymes that catalyze complex reaction processes in extreme environmental conditions. Accordingly, a combined approach consisting of extremozyme screening, ancestral sequence resurrection (ASR), and molecular dynamic simulation was utilized to construct a developed endoglucanase. The primary experimental and in-silico data led to the prediction of a hypothetical sequence of endoglucanase (EG5-G131) using Bacillus sp. G131 confirmed by amplification and sequencing. EG5-G131 exhibited noticeable stability in a broad-pH range, several detergents, organic solvents, and temperatures up to 80 °C. The molecular weight, Vmax, and Km of the purified endoglucanase were estimated to be 36 kDa, 4.32 μmol/min, and 23.62 mg/ml, respectively. The calculated thermodynamic parameters for EG5-G131 confirmed its intrinsic thermostability. Computational analysis revealed Glu142 and Glu230 as active-site residues of the enzyme. Furthermore, the enzyme remained bound to cellotetraose at 298 K, 333 K, 343 K, and 353 K for 300 ns, consistent with our experimental data. ASR of EG5-G131 led to the introduction of ancestral ANC204 and ANC205, which show similar thermodynamic characteristics with the last Firmicute common ancestor. Finally, truncating loops from the N-terminal of two sequences created two variants with desirable thermal stability, suggesting the evolutionary deciphering of the functional domain of the GH5 family in Bacillus sp. G131.

Genome information of the cellulolytic soil actinobacterium Isoptericola dokdonensis DS-3 and comparative genomic analysis of the genus Isoptericola

The actinobacterial group is regarded as a reservoir of biologically active natural products and hydrolytic enzymes with the potential for biomedical and industrial applications. Here, we present the complete genome sequence of Isoptericola dokdonensis DS-3 isolated from soil in Dokdo, small islets in the East Sea of Korea. This actinomycete harbors a large number of genes encoding carbohydrate-degrading enzymes, and its activity to degrade carboxymethyl cellulose into glucose was experimentally evaluated. Since the genus Isoptericola was proposed after reclassification based on phylogenetic analysis, strains of Isoptericola have been continuously isolated from diverse environments and the importance of this genus in the ecosystem has been suggested by recent culturomic or metagenomic studies. The phylogenic relationships of the genus tended to be closer among strains that had been isolated from similar habitats. By analyzing the properties of published genome sequences of seven defined species in the genus, a large number of genes for carbohydrate hydrolysis and utilization, as well as several biosynthetic gene clusters for secondary metabolites, were identified. Genomic information of I. dokdonensis DS-3 together with comparative analysis of the genomes of Isoptericola provides insights into understanding this actinobacterial group with a potential for industrial applications.

A Thermostable Aspergillus fumigatus GH7 Endoglucanase Over-Expressed in Pichia pastoris Stimulates Lignocellulosic Biomass Hydrolysis

In the context of avoiding the use of non-renewable energy sources, employing lignocellulosic biomass for ethanol production remains a challenge. Cellulases play an important role in this scenario: they are some of the most important industrial enzymes that can hydrolyze lignocellulose. This study aims to improve on the characterization of a thermostable Aspergillus fumigatus endo-1,4-β-glucanase GH7 (Af-EGL7). To this end, Af-EGL7 was successfully expressed in Pichia pastoris X-33. The kinetic parameters K_m and V_max were estimated and suggested a robust enzyme. The recombinant protein was highly stable within an extreme pH range (3.0-8.0) and was highly thermostable at 55 °C for 72 h. Low Cu²⁺ concentrations (0.1-1.0 mM) stimulated Af-EGL7 activity up to 117%. Af-EGL7 was tolerant to inhibition by products, such as glucose and cellobiose. Glucose at 50 mM did not inhibit Af-EGL7 activity, whereas 50 mM cellobiose inhibited Af-EGL7 activity by just 35%. Additionally, the Celluclast^® 1.5L cocktail supplemented with Af-EGL7 provided improved hydrolysis of sugarcane bagasse "in natura", sugarcane exploded bagasse (SEB), corncob, rice straw, and bean straw. In conclusion, the novel characterization of Af-EGL7 conducted in this study highlights the extraordinary properties that make Af-EGL7 a promising candidate for industrial applications.