A systematic review of the genera Geobacillus and Parageobacillus: their evolution, current taxonomic status and major applications

Abstract

The genus Geobacillus , belonging to the phylum Firmicutes, is one of the most important genera and comprises thermophilic bacteria. The genus Geobacillus was erected with the taxonomic reclassification of various Bacillus species. Taxonomic studies of Geobacillus remain in progress. However, there is no comprehensive review of the characteristic features, taxonomic status and study of various applications of this interesting genus. The main aim of this review is to give a comprehensive account of the genus Geobacillus . At present the genus acomprises 25 taxa, 14 validly published (with correct name), nine validly published (with synonyms) and two not validly published species. We describe only validly published species of the genera Geobacillus and Parageobacillus . Vegetative cells of Geobacillus species are Gram-strain-positive or -variable, rod-shaped, motile, endospore-forming, aerobic or facultatively anaerobic, obligately thermophilic and chemo-organotrophic. Growth occurs in the pH range 6.08.5 and a temperature of 37–75 °C. The major cellular fatty acids are iso-C15:o, iso-C16:0 and iso-C17:o. The main menaquinone type is MK-7. The G­+C content of the DNA ranges between 48.2 and 58 mol%. The genus Geobacillus is widely distributed in nature, being mostly found in many extreme locations such as hot springs, hydrothermal vents, marine trenches, hay composts, etc. Geobacillus species have been widely exploited in various industrial and biotechnological applications, and thus are promising candidates for further studies in the future.

Antimicrobial Potential of the Genera Geobacillus and Parageobacillus, as Well as Endolysins Biosynthesized by Their Bacteriophages

“…Geobacillus and Parageobacillus genera belong to the Bacillaceae family, which is a large and heterogeneous group that includes many mesophilic, facultative thermophilic and thermophilic species, widely distributed in different habitats [ 1 ]. The current taxonomic classification of Geobacillus and Parageobacillus is presented in Figure 1 .…”

“…The current taxonomic classification of Geobacillus and Parageobacillus is presented in Figure 1 . Their closest evolutionary relatives are bacteria of the genus Bacillus , exemplified by Bacillus subtilis ( B. subtilis ) [ 1 ]. B. subtilis strains and other species from the genus Bacillus are well known for their probiotic properties and production of various antimicrobial compounds [ 2 , 3 , 4 ].…”

“…They have been detected on all continents and also in the seas, oceans and even in the atmosphere [ 5 , 6 ]. Representatives of these genera can be isolated from extreme places such as hot springs, hydrothermal vents, high-temperature oil fields, composts, and greenhouse soil [ 1 , 6 ]. Interestingly, they have also been found (in large numbers) in cold places, much below their minimal growth temperatures, such as ocean sediments or soil samples [ 6 ].…”

“…The structure of their cell walls is Gram-positive, but the result of the gram-stain reaction may be varied. Cells are motile or non-motile and can occur individually or in chains [ 1 , 5 , 7 ]. Cellular fatty acids are characterized by iso-15:0, iso-16:0 and iso-17:0.…”

Phylogenetic study of thermophilic genera Anoxybacillus, Geobacillus, Parageobacillus, and proposal of a new classification Quasigeobacillus gen. nov.

“…A partial phylogenetic analysis of G. galactosidasius by Ramaloko et al [48], came to conclusion that G. galactosidasius should properly belong to Parageobacillus . Najar and Thakur [49] proposed the formal reclassification of G. galactosidasius to P. galactosidasius and G. yumthangensis to P. yumthangensis . The data from the present study agrees with this conclusion and we are following this reclassification for the taxonomy used in this study.…”