Genomic and functional insights into the thermophilic strain Geobacillus sp. Geo 8.1: a source of thermostable xylanase for sustainable bioprocesses

A thermophilic bacterium, designated Geobacillus sp. Geo 8.1, was isolated from a submarine hydrothermal spring of Ischia Island (Italy) and characterized through genomic and biochemical analyses to evaluate its biotechnological potential. The draft genome (3.41 Mbp; GC 52.5%) revealed 3,751 coding sequences, including complete pathways for carbohydrate, lipid, and protein metabolism, and enzymes involved in stress response and hydrocarbon degradation. Phylogenomic and digital DNA-DNA hybridization analyses placed Geo 8.1 within the Geobacillus thermoleovorans/Geobacillus kaustophilus cluster. Functional annotation highlighted diverse genes encoding thermostable hydrolases such as xylanases, beta-xylosidases, lipases, proteases, and alpha-amylases, together with catalases and dehalogenases relevant to environmental and industrial applications. Crude enzyme extracts exhibited strong xylanase activity (184 U/mL at 65 degrees C), and thin-layer chromatography confirmed the production of xylose as the major hydrolysis product, indicating the coordinated action of endo-xylanase and beta-xylosidase. Genome reconstruction further demonstrated a complete D-xylose utilization pathway linking hemicellulose degradation to central carbon metabolism. The combined genomic and enzyme data reveal Geobacillus sp. Geo 8.1 represents a promising thermophilic biocatalyst for producing thermostable enzymes applicable to lignocellulose valorization, bioremediation, and various industrial processes.