To clarify the evolutionary relationships and classification of Bacillus species, comprehensive phylogenomic and comparative analyses were performed on >300 Bacillus/Bacillaceae genomes. Multiple genomic-scale phylogenetic trees were initially reconstructed to identify different monophyletic clades of Bacillus species. In parallel, detailed analyses were performed on protein sequences of genomes to identify conserved signature indels (CSIs) that are specific for each of the identified clades. We show that in different reconstructed trees, most of the Bacillus species, in addition to the Subtilis and Cereus clades, consistently formed 17 novel distinct clades. Additionally, some Bacillus species reliably grouped with the genera Alkalicoccus, Caldalkalibacillus, Caldibacillus, Salibacterium and Salisediminibacterium. The distinctness of identified Bacillus species clades is independently strongly supported by 128 identified CSIs which are unique characteristics of these clades, providing reliable means for their demarcation. Based on the strong phylogenetic and molecular evidence, we are proposing that these 17 Bacillus species clades should be recognized as novel genera, with the names Alteribacter gen. nov., Ectobacillus gen. nov., Evansella gen. nov., Ferdinandcohnia gen. nov., Gottfriedia gen. nov., Heyndrickxia gen. nov., Lederbergia gen. nov., Litchfieldia gen. nov., Margalitia gen. nov., Niallia gen. nov., Priestia gen. nov., Robertmurraya gen. nov., Rossellomorea gen. nov., Schinkia gen. nov., Siminovitchia gen. nov., Sutcliffiella gen. nov. and Weizmannia gen. nov. We also propose to transfer 'Bacillus kyonggiensis' to Robertmurraya kyonggiensis sp. nov. (type strain: NB22=JCM 17569T=DSM 26768). Additionally, we report 31 CSIs that are unique characteristics of either the members of the Subtilis clade (containing the type species B. subtilis) or the Cereus clade (containing B. anthracis and B. cereus). As most Bacillus species which are not part of these two clades can now be assigned to other genera, we are proposing an emended description of the genus Bacillus to restrict it to only the members of the Subtilis and Cereus clades.

Erratum: Robust demarcation of seventeen distinct Bacillus species clades, proposed as novel Bacillaceae genera, by phylogenomics and comparative genomic analyses: description of Robertmurraya kyonggiensis sp. nov. and proposal for emended genus Bacillus limiting it only to the members of the subtilis and cereus clades of species.

Aims: To identify the diversity of pigmented aerobic spore formers found in the environment and to characterize the chemical nature of this pigmentation.



Materials and Results:  Sampling of heat-resistant bacterial counts from soil, sea water and the human gastrointestinal tract. Phylogenetic profiling using analysis of 16S rRNA sequences to define species. Pigment profiling using high-performance liquid chromatography-photo diode array analysis.



Conclusions:  The most commonly found pigments were yellow, orange and pink. Isolates were nearly always members of the Bacillus genus and in most cases were related with known species such as Bacillus marisflavi, Bacillus indicus, Bacillus firmus, Bacillus altitudinis and Bacillus safensis. Three types of carotenoids were found with absorption maxima at 455, 467 and 492 nm, corresponding to the visible colours yellow, orange and pink, respectively. Although the presence of other carotenoids cannot be ruled out, these three predominant carotenoids appear to account for the pigments obtained in most pigmented bacilli, and our analysis reveals the existence of a C30 biosynthetic pathway. Interestingly, we report the presence of a water-soluble pigment that may also be a carotenoid. The function of carotenoids is photoprotection, and carotenoid-containing spores exhibited significantly higher levels of resistance to UV radiation than non–carotenoid-containing Bacillus species.



Significance and Impact of the Study:  This study demonstrates that pigmented bacilli are ubiquitous and contain new carotenoid biosynthetic pathways that may have industrial importance.

Carotenoids found in Bacillus.

The mobile genetic element ICEBs1 is an integrative and conjugative element (a conjugative transposon) found in the Bacillus subtilis chromosome. The SOS response and the RapI-PhrI sensory system activate ICEBs1 gene expression, excision and transfer by inactivating the ICEBs1 repressor protein ImmR. Although ImmR is similar to many characterized phage repressors, we found that, unlike these repressors, inactivation of ImmR requires an ICEBs1-encoded anti-repressor ImmA (YdcM). ImmA was needed for the degradation of ImmR in B. subtilis. Coexpression of ImmA and ImmR in Escherichia coli or co-incubation of purified ImmA and ImmR resulted in site-specific cleavage of ImmR. Homologues of immR and immA are found in many mobile genetic elements. We found that the ImmA homologue encoded by B. subtilis phage phi105 is required for inactivation of the phi105 repressor (an ImmR homologue). ImmA-dependent proteolysis of ImmR repressors may be a conserved mechanism for regulating horizontal gene transfer.

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A conserved anti-repressor controls horizontal gene transfer by proteolysis

Twenty alkaliphilic bacterial strains from industrial applications or enzyme studies were subjected to a polyphasic taxonomic investigation, including 16S rRNA gene sequencing, determination of genomic DNA G+C content, DNA–DNA hybridization, fatty acid analysis and standard bacteriological characterization. By comparing the groupings obtained based on the genomic DNA G+C content and the construction of a phylogenetic tree based on the 16S rRNA gene sequence, 12 clusters of similar strains were recognized. DNA–DNA hybridization revealed that these clusters represented five novel genospecies. Further analysis supported the proposal of five novel species in the genus Bacillus: Bacillus wakoensis sp. nov. (type strain N-1T=JCM 9140T=DSM 2521T), Bacillus hemicellulosilyticus sp. nov. (type strain C-11T=JCM 9152T=DSM 16731T), Bacillus cellulosilyticus sp. nov. (type strain N-4T=JCM 9156T=DSM 2522T), Bacillus akibai sp. nov. (type strain 1139T=JCM 9157T=ATCC 43226T) and Bacillus mannanilyticus sp. nov. (type strain AM-001T=JCM 10596T=DSM 16130T).

Characterization of alkaliphilic Bacillus strains used in industry: proposal of five novel species.

https://espace.library.uq.edu.au/view/UQ:355001/UQ35501_OA.pdf

Microbially-driven strategies for bioremediation of bauxite residue

Isolation and Characterization of Novel Alkaliphiles from Bauxite-Processing Waste and Description of Bacillus vedderi sp. nov., a New Obligate Alkaliphile

The sequence of the genome of the first alkaliphilic bacteriophage has been determined. Temperate phage BCJA1 possesses a terminally redundant genome of approximately 41 kb, with a mol% G + C content of 41.7 and 59 genes arranged predominantly into two divergent transcriptons. The integrase gene of this phage is unique in that it contains a ribosomal slippage site. While this type of translational regulation occurs in the synthesis of transposase, this is the first time that it has been observed in a bacteriophage integrase. The DNA replication, recombination, packaging, and morphogenesis proteins show their greatest sequence similarity to phages and prophages from the genus Streptococcus. Host specificity, lysin, and lysogeny maintenance functions are most closely related to genes from Bacillus species.

The genome of BCJA1c: a bacteriophage active against the alkaliphilic bacterium, Bacillus clarkii.

The isolation and characterization of a novel bacteriophage active against the obligately alkaliphilic bacterium Bacillus clarkii is described. The bacteriophage, designated BCJA1, is a member of the Siphoviridae family with a B1 morphology. It possesses an isometric head, which measures 65 nm between opposite apices, and a noncontractile tail of 195 nm length. It had a buoyant density of 1.518 g/ml and an estimated particle mass of 37 × 107 daltons. BCJA1 was stable over the pH range of 6–11. A one-step growth experiment conducted at pH 10 demonstrated a latent period of about 40 min and a burst size of approximately 40. The purified bacteriophage appeared to consist of 10 proteins with the major head and tail proteins likely to be of molecular weight 36 500 and 28 000, respectively. The genome size was estimated to be between 32.1 and 34.8 kb. The percent G + C content of purified bacteriophage DNA was 45.6. The wildtype bacteriophage is temperate but a clear plaque mutant was isolated.

M. Dorothy Agnew

Papers

Isolation and Characterization of Novel Alkaliphiles from Bauxite-Processing Waste and Description of Bacillus vedderi sp. nov., a New Obligate Alkaliphile

The genome of BCJA1c: a bacteriophage active against the alkaliphilic bacterium, Bacillus clarkii.

Isolation and characterization of bacteriophage BCJA1, a novel temperate bacteriophage active against the alkaliphilic bacterium, Bacillus clarkii.