We used rpoB partial sequencing and multilocus sequence typing (MLST) to characterize 7 Bacillus cereus strains obtained at the following points: ESL milk during shelf life, pasteurized milk, raw milk, and filler nozzles after cleaning in place. The objective of the study was to determine relatedness among B. cereus isolates from several sampling points along an ESL processing plant with the aim of source tracking. The study revealed that isolates from filler nozzles shared 100% similarity with isolates from ESL milk and raw milk using rpoB sequencing. It also revealed that isolates from pasteurized milk shared 100% similarities with isolates from filler nozzles and ESL milk using MLST. We suggest 3 routes of B. cereus contamination in ESL milk. We showed that B. cereus contamination of ESL milk might be through raw milk and biofilms from filler nozzles. In addition, rpoB partial sequencing and MLST can be used as tools for source tracking in ESL milk processing.

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Bacillus oleronius strain DSM 9356 isolated from the termite Reticulitermes santonensis was sequenced to gain insights in relation to its closest phylogenetic neighbor Bacillus sporothermodurans. The draft genome of strain DSM 9356 contains 5,083,966 bp with an estimated G + C content of 35%, 4899 protein-coding genes, 116 tRNAs and 18 rRNAs. The RAST annotation assigned these genes into 462 subsystems, with the maximum number of genes associated with amino acids and derivatives metabolism (14.84%), followed by carbohydrates (13.89%) and protein metabolism subsystems (9.10%). The draft genome sequence and annotation has been deposited at NCBI under the accession number MTLA00000000.

Here, we report the draft genome sequences of 3 Bacillus sporothermodurans strains isolated from ultra-high-temperature milk products in South Africa and Brazil and the type strain MB 581 (DSM 10599). The genomes will provide valuable information on the molecular dynamics of heat resistance in B.

Bacillus sporothermodurans 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 B. sporothermodurans provided an opportunity to perform the first comparative genome analysis between strains and with B. oleronius, B. cereus, and B. subtilis groups. In this study, five whole genome sequences of B. sporothermodurans strains, including those belonging to the HRS clone (SAD and BR12) normally isolated from UHT milk, were compared with the aforementioned Bacillus species for gene clusters responsible for heat resistance. In the phylogenomic analysis, B. sporothermodurans, with its closest phylogenetic neighbor, B. oleronius, clustered with B. thermoamylovorans and B. thermotolerans. Heat shock proteins GrpE, GroES, GroEL, and DnaK presented identical sequences for all B. sporothermodurans strains, indicating that differences in functional efficiency are not involved in the thermal resistance variations. However, comparing all species evaluated, B. sporothermodurans exhibited a different gene configuration in the chromosomal region of the heat shock protein GrpE. Furthermore, only B. sporothermodurans 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 B. sporothermodurans. Bacillussporothermodurans exhibits high homology with other Bacillus 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.