A thermophilic and phospholipid-degrading bacterium, designated strain B157 T , was isolated from acidulocompost, a garbage compost processed under acidic conditions at moderately high temperature. The organism was Gram-stain-positive, aerobic, spore-forming and rod-shaped. Growth was observed to occur at 40-65 C and pH 4.8-8.1 (optimum growth: 50-60 C, pH 6.2). The strain was catalase-and oxidase-positive. The cell wall contained meso-diaminopimelic acid, alanine, glutamic acid and galactose. The predominant respiratory quinone was menaquinone-7 (MK-7) and the major fatty acids were anteiso-C 17 : 0 and iso-C 17 : 0 . Comparative 16S rRNA gene sequence analysis showed that strain B157 T was related most closely to Tuberibacillus calidus 607 T (94.8 % identity), and the phylogenetic analysis revealed that it belonged to the family Sporolactobacillaceae. The DNA G+C content was determined as 51.8 mol%. In spite of many similarities with the type strains of members of the family Sporolactobacillaceae, genotypic analyses suggest that strain B157 T represents a novel species of a new genus, Caenibacillus caldisaponilyticus gen. nov., sp. nov. The type strain of Caenibacillus caldisaponilyticus is B157 T (=NBRC 111400 T =DSM 101100 T ).