Comparative Genome Analysis of with Its Closest Phylogenetic Neighbor, , and and Groups.

currently possesses one of the most highly heat-resistant spores (HRS), which can withstand ultra-high temperature (UHT) processing. Determination of multiple whole genome sequences of . provided an opportunity to perform the first comparative genome analysis between strains and with . , . , and . groups. In this study, five whole genome sequences of strains, including those belonging to the HRS clone (SAD and BR12) normally isolated from UHT milk, were compared with the aforementioned species for gene clusters responsible for heat resistance. In the phylogenomic analysis, , with its closest phylogenetic neighbor, . , clustered with . and . Heat shock proteins GrpE, GroES, GroEL, and DnaK presented identical sequences for all . strains, indicating that differences in functional efficiency are not involved in the thermal resistance variations. However, comparing all species evaluated, . exhibited a different gene configuration in the chromosomal region of the heat shock protein GrpE. Furthermore, only . strains presented the stage II sporulation protein P gene located in this region. Multisequence alignment and phylogenetic analysis of the ClpB protein showed differences for HRS and non-HRS strains. The study identified ClpC, ClpE, and ClpX as the three ATPases putatively involved in protein disaggregation in . . exhibits high homology with other species in the DnaK, DnaJ, GroEL, and GroES cluster of genes involved in heat resistance. The data presented here pave the way to select and evaluate the phenotypic effects of genes putatively involved in heat resistance.