## 1 Introduction  
The genus _Geobacillus_ comprises thermophilic, Gram-positive, spore-forming, rod-shaped bacteria that are either aerobic or facultatively anaerobic, constituting a phylogenetically coherent clade within the family Bacillaceae [1]. These microorganisms inhabit a wide range of environments, including hot springs, cold regions, and ocean sediments [2]. The genus _Geobacillus_ was proposed by [PERSON] et al. (2001) [3] to differentiate it from the genus _Bacillus_ based on distinct physiological traits, variations in growth temperatures, and phenotypic characteristics among strains. _Geobacillus_ species exhibit broad catabolic versatility, facilitating their widespread occurrence across diverse environments. These bacteria are recognized for secreting commercially important enzymes, including lipases, xylanas, and amylases, widely utilized in various industrial and biotechnological processes. According to the List of Prokaryotic Names with Standing in Nomenclature (LPSN, 2025), the genus _Geobacillus_ currently includes 30 valid species, including _Geobacillus thermodynamic_, _Geobacillus uzenensis_, _Geobacillus_ _thermactenulatus_, _Geobacillus_ _kantophilus_, _Geobacillus_ _thermoglucosidasus_, _Geobacillus_ _thermactorans_, _Geobacillus_ _subterraneus_, _Geobacillus_ _lux_ _stearothermophilus_, _Geobacillus_ _toebi_, _Geobacillus_ _jurassicus_, _Geobacillus_ _thermoglucosidas_, _Geobacillus_ _stearothermophilus_, and _Geobacillus_ _thermodenitrificants_. _Geobacillus_ _stearothermophilus_ serves as the type species, with DSM 22 designated as its type strain [1,4]. Analysis based on the 16S rRNA gene revealed a cohesive grouping of 56 _Geobacillus_ strains, exhibiting intra-species similarities between 99.3% and 100%, and inter-species similarities ranging from 96.0% to 99.4%, facilitating reliable distinctions [5]. However, limitations in taxonomic resolution using the 16S rRNA gene led researchers to adopt additional genetic markers, such as recN, infB, rpoB, and spo0A, providing enhanced phylogenetic clarity [6,7]. Distinctions between _Geobacillus_ species in previous studies have been based on small chemotaxonomic differences and phenotypic characteristics [5]. Growth temperatures range from 35 \({}^{\circ}\)C to 80 \({}^{\circ}\)C, with most isolated strains growing between 45 \({}^{\circ}\)C and 70 \({}^{\circ}\)C [3]. The core genome of _Geobacillus_ comprises approximately 1665 genes, 85% of which are shared with the genome of _Bacillus subtilis_ 168, suggesting a common survival strategy centered around rapid growth and sporulation under nutrient-limited conditions [8]. Traditionally, bacterial classification has relied on methods such as 16S rRNA sequencing, DNA-DNA hybridization (DDH), and phenotypic characterization. Nonetheless, high sequence similarity within the 16S rRNA gene among _Geobacillus_ species complicates precise identification and has resulted in misidentifications [9]. The growing number of studies classifying new species using only single-pathway markers has led to the rise of unreliable and confusing classifications within the genus [3,10,11,12]. To overcome these challenges, integrated approaches combining genomic and phenotypic analyses, including whole-genome sequencing, have been proposed to achieve higher phylogenetic resolution. The Calientes geothermal field in Tacna, Peru, represents an underexplored source of microbial biodiversity with significant biotechnological potential [13,14]. Characterized by elevated temperatures and unique mineral compositions, these geothermal springs provide optimal conditions for thermophilic bacteria like _Geobacillus_[15,16]. These microorganisms have attracted considerable interest due to their ability to produce thermostable enzymes applicable in biotechnology, particularly in industrial processes involving the bioconversion and biodegradation of complex organic polymers such as lignocellulosic biomass (e.g., cellulose, hemicellulose, and lignin) [17].