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

Genomic analysis of Isoptericola halotolerans SM2308 reveals its potential involved in fucoidan degradation

Marine bacteria play important roles in the degradation and recycling of algal polysaccharides. However, the marine bacteria involved in fucoidan degradation and their degradation pathways remain poorly understood. Here, we report the complete genome sequence of Isoptericola halotolerans SM2308, isolated from a brown algal sample collected from an intertidal zone of the Yellow Sea in China. The genome of strain SM2308 consists of a single circular chromosome of 4,011,455 bp with a high GC content of 72.70 %. Strain SM2308 exhibited rapid growth on fucoidan as the sole carbon source, indicating its capacity to degrade fucoidan. Gene annotation and metabolic pathway analyses showed that strain SM2308 possesses a complete pathway for utilizing fucoidan, including the extracellular breakdown of polymeric fucoidan into smaller fucooligosaccharides/fucose by fucoidanases, the transmembrane transport of fucooligosaccharides/fucose into the cytoplasm by an ABC transporter, and the intracellular fucose catabolism via a non-phosphorylative pathway. This represents the first genome of an actinobacterium from the order Micrococcales with fucoidan-degrading ability. The genome of Isoptericola halotolerans SM2308 provides insights into the role of actinobacteria in the biogeochemical cycling of fucoidan in marine ecosystems.

Assessing hydrocarbon degradation capacity of Isoptericola peretonis sp. nov. and related species: a comparative study

Since the beginning of their production and use, fossil fuels have affected ecosystems, causing significant damage to their biodiversity. Bacterial bioremediation can provide solutions to this environmental problem. In this study, the new species Isoptericola peretonis sp. nov. 4D.3T has been characterized and compared to other closely related species in terms of hydrocarbon degradation and biosurfactant production by in vitro and in silico analyses. Biosurfactants play an important role in microbial hydrocarbon degradation by emulsifying hydrocarbons and making them accessible to the microbial degradation machinery. The tests performed showed positive results to a greater or lesser degree for all strains. In the synthesis of biosurfactants, all the strains tested showed biosurfactant activity in three complementary assays (CTAB, hemolysis and E24%) and rhamnolipid synthesis genes have been predicted in silico in the majority of Isoptericola strains. Regarding hydrocarbon degradation, all the Isoptericola strains analyzed presented putative genes responsible for the aerobic and anaerobic degradation of aromatic and alkane hydrocarbons. Overall, our results highlight the metabolic diversity and the biochemical robustness of the Isoptericola genus which is proposed to be of interest in the field of hydrocarbon bioremediation.

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.