Endospore-forming strains were isolated from corn-compost treated with olive-mill wastewater ('alpechin'). The strains were taxonomically studied and proposed as a novel Paenibacillus species. These organisms (strains B.3T, B.7 and B.9) were particularly distinguishable from other aerobic spore-forming species by their ability to grow optimally in 100% (v/v) olive-mill wastewater at 30 degrees C and pH 7.0 and concomitant production of an interesting exopolysaccharide. Chemotaxonomic analysis revealed that MK-7 was the predominant menaquinone, the major fatty acid was anteiso C15:0 and the cell wall contained meso-diaminopimelic acid. The DNA G+C content was 40.7 mol%. Comparative sequence analysis of 16S rDNA with different reference species from the genera Bacillus, Paenibacillus, Brevibacillus, Aneurinibacillus, Alicyclobacillus, Halobacillus, Virgibacillus, Amphibacillus, Coprobacillus and Gracilibacillus indicated that the isolated strains were highly related to the genus Paenibacillus. Strain B.3T formed an evolutionary lineage distinct from other species within the evolutionary radiation encompassing the genus Paenibacillus. Strain B.3T was a close relative of Paenibacillus polymyxa, but DNA-DNA relatedness data with this species was very low (relative binding ratio < 16%). Based on the morphological and physiological characteristics, as well as on the phylogenetic position determined by 16S rDNA analysis and DNA-DNA relatedness data, it is concluded that these strains should be designated a novel species, for which the name Paenibacillus jamilae sp. nov. is proposed. The type strain is B.3T (= CECT 5266T = DSM 13815T).