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Bacillus mojavensis sp. nov., distinguishable from Bacillus subtilis by sexual isolation, divergence in DNA sequence, and differences in fatty acid composition.

A number of Bacillus strains isolated from desert soil samples were shown to belong to a previously unidentified species, for which we propose the name Bacillus mojavensis. The type strain is RO-H-1 (= NRRL B-14698). On the basis of restriction digest data, B. mojavensis is most closely related to Bacillus amyloliquefaciens, Bacillus atrophaeus, and Bacillus subtilis. So far, B. mojavensis can be distinguished from B. subtilis only by differences in whole-cell fatty acid composition, divergence in DNA sequence, and resistance to genetic transformation between taxa (in addition to reduced genome relatedness values). Sequence divergence and sexual isolation may prove to be more useful than metabolic characteristics for delimiting cryptic Bacillus species.

Bacillus↗

Growth-inhibiting effects of concentrations of fusaric acid on the growth of Bacillus mojavensis and other biocontrol Bacillus species.

AIMS: To determine the effects of concentrations of fusaric acid on the growth of several strains of the biocontrol bacterial endophyte Bacillus mojavensis and other species within the Bacillus subtilis group, as well as the genetic relationships within this small group of Gram-positive bacteria, and their antagonisms to Fusarium verticillioides, which produce fusaric acid. METHODS AND RESULTS: The growth of 50 Bacillus strains and species were tested at two concentrations of fusaric acid determined in maize infected by an isolate of F. verticillioides. Molecular characterizations of the strains and species of bacteria were determined with an automated ribotyper. The growth of bacteria measured under both concentrations with an automated turbidometer, Bioscreen, indicated that fusaric acid was toxic to most strains of the bacterial endophyte B. mojavensis. However, the effects of these two concentrations on other Bacillus species varied in that fusaric acid was either bacteriocidal or bacteriostatic to most species. CONCLUSIONS: These data indicate that the concentrations of fusaric acid are inhibitory to the growth of most Bacillus species, some of which are used as biocontrol agents. This suggests that the endophytic and saprophytic states of F. verticillioides and other Fusarium species cannot be controlled by fusaric-acid-sensitive Bacillus species. SIGNIFICANCE AND IMPACT OF STUDY: Mycotoxic Fusarium species, such as F. verticillioides, are competitive because all produce fusaric acid, which is inhibitory to biocontrol bacteria, and mutants tolerant to fusaric acid must be developed in order to be effective on biocontrol bacteria.

Bacillus↗

Bacillus weihenstephanensis sp. nov. is a new psychrotolerant species of the Bacillus cereus group.

The Bacillus cereus group comprises the four valid species Bacillus cereus, Bacillus mycoides, Bacillus thuringiensis and bacillus anthracis. Some isolates of B. cereus are known to be psychrotolerant (growth at 7 degrees C or below). Here, specific sequence differences are described between the 16S rDNA, the 23S rDNA, the 16S-23S rDNA spacer region and the genes of the major cold-shock protein homologue cspA in a variety of psychrotolerant and mesophilic B. cereus and B. mycoides strains. Randomly amplified polymorphic DNA analysis using three different primers clearly separated psychrotolerant strains of both species from the rest of the B. cereus group, as did inverse PCR patterns of the rDNA operons. These data strongly support a hitherto unrecognized fifth sub-group within the B. cereus species group comprising psychrotolerant, but not mesophilic, B. cereus strains. Despite the latter finding, the DNA sequences investigated exhibited a high degree of sequence similarity indicating a close relationship between the species of the B. cereus group. Considering the unusual importance of B. cereus in both food poisoning and food spoilage and to avoid merging all species of the group, a new species, Bacillus weihenstephanensis sp. nov., comprising psychrotolerant 'cereus' strains, is proposed. Isolates of the new species grow at 4-7 degrees C but not at 43 degrees C and can be identified rapidly using rDNA or cspA targeted PCR. The type strain is B. weihenstephanensis WSBC 10204T (= DSM 11821T).

Animals↗

Bacillus tequilensis sp. nov., isolated from a 2000-year-old Mexican shaft-tomb, is closely related to Bacillus subtilis.

A Gram-positive, spore-forming bacillus was isolated from a sample taken from an approximately 2000-year-old shaft-tomb located in the Mexican state of Jalisco, near the city of Tequila. Tentative identification using conventional biochemical analysis consistently identified the isolate as Bacillus subtilis. DNA isolated from the tomb isolate, strain 10b(T), and closely related species was used to amplify a Bacillus-specific portion of the highly conserved 16S rRNA gene and an internal region of the superoxide dismutase gene (sodA(int)). Trees derived from maximum-likelihood methods applied to the sodA(int) sequences yielded non-zero branch lengths between strain 10b(T) and its closest relative, whereas a comparison of a Bacillus-specific 546 bp amplicon of the 16S rRNA gene demonstrated 99 % similarity with B. subtilis. Although the 16S rRNA gene sequences of strain 10b(T) and B. subtilis were 99 % similar, PFGE of NotI-digested DNA of strain 10b(T) revealed a restriction profile that was considerably different from those of B. subtilis and other closely related species. Whereas qualitative differences in whole-cell fatty acids were not observed, significant quantitative differences were found to exist between strain 10b(T) and each of the other closely related Bacillus species examined. In addition, DNA-DNA hybridization studies demonstrated that strain 10b(T) had a relatedness value of less than 70 % with B. subtilis and other closely related species. Evidence from the sodA(int) sequences, whole-cell fatty acid profiles and PFGE analysis, together with results from DNA-DNA hybridization studies, justify the classification of strain 10b(T) as representing a distinct species, for which the name Bacillus tequilensis sp. nov. is proposed. The type strain is 10b(T) (=ATCC BAA-819(T)=NCTC 13306(T)).

Archaeology↗

Genotyping of starter cultures of Bacillus subtilis and Bacillus pumilus for fermentation of African locust bean (Parkia biglobosa) to produce Soumbala.

Bacillus spp. are the predominant microorganisms in fermented African locust bean called Soumbala in Burkina Faso. Ten strains selected as potential starter cultures were characterised by PCR amplification of the16S-23S rDNA intergenic transcribed spacer (ITS-PCR), restriction fragment length polymorphism of the ITS-PCR (ITS-PCR RFLP), pulsed field gel electrophoresis (PFGE) and sequencing of the 968-1401 region of the 16S rDNA. In previous studies, the isolates were identified by phenotyping as Bacillus subtilis and Bacillus pumilus. The phenotyping was repeated as a reference in the present study. The ITS-PCR and ITS-PCR RLFP allowed a typing at species level. The PFGE was more discriminative and allowed a typing at strain level. Full agreement with the phenotyping was observed in all cases. The sequencing of the 16S rDNA allowed the identification at species level with an identity from 97% to 100% comparing the sequences to those from the GenBank databases. The desired cultures of B. subtilis and B. pumilus from African locust bean fermentation were distinguished by ITS-PCR and ITS-PCR RLFP from Bacillus cereus and Bacillus sphaericus which sometimes occur in the beginning of the fermentation.

Bacillus↗

Genome organization is not conserved between Bacillus cereus and Bacillus subtilis.

The opportunistic pathogen Bacillus cereus is the genetically stable member of a group of closely related bacteria including the insect pathogen Bacillus thuringiensis and the mammalian pathogen Bacillus anthracis. Physical maps of B. cereus and B. thuringiensis strains show considerable variations in discrete parts of the chromosome, suggesting that certain genome regions are more prone to rearrangements. B. cereus belongs to the same subgroup of Bacillus species as Bacillus subtilis, by both phenotypic and rRNA sequence classification. The analysis of 80 kb of genome sequence sampled from different regions of the B. cereus ATCC 10987 chromosome is reported. Analysis of the sequence and comparison of the localization of the putative genes with that of B. subtilis orthologues show the following: (1) gene organization is not conserved between B. cereus and B. subtilis; (2) several putative genes are more closely related to genes from other bacteria and archaea than to B. subtilis, or may be absent in B. subtilis 168; (3) B. cereus contains a 155 bp repetitive sequence that is not present in B. subtilis. By hybridization, this repeat is present in all B. cereus and B. thuringiensis strains so far investigated.

Bacillus cereus↗

Anaerobic growth of Bacillus mojavensis and Bacillus subtilis requires deoxyribonucleosides or DNA.

Bacillus mojavensis strains JF-2 (ATCC 39307), ROB2, and ABO21191(T) and Bacillus subtilis strains 168 (ATCC 23857) and ATCC 12332 required four deoxyribonucleosides or DNA for growth under strict anaerobic conditions. Bacillus licheniformis strains L89-11 and L87-11, Bacillus sonorensis strain TG8-8, and Bacillus cereus (ATCC 14579) did not require DNA for anaerobic growth. The requirement for the deoxyribonucleosides or DNA did not occur under aerobic growth conditions. The addition of a mixture of five nucleic acid bases, four ribonucleotides, or four ribonucleosides to the basal medium did not replace the requirement of B. mojavensis JF-2 for the four deoxyribonucleosides. However, the addition of salmon sperm DNA, herring sperm DNA, Escherichia coli DNA, or synthetic DNA (single or double stranded) to the basal medium supported anaerobic growth. The addition of four deoxyribonucleosides to the basal medium allowed aerobic growth of B. mojavensis JF-2 in the presence of hydroxyurea. B. mojavensis did not grow in DNA-supplemented basal medium that lacked sucrose as the energy source. These data provide strong evidence that externally supplied deoxyribonucleosides can be used to maintain a balanced deoxyribonucleotide pool for DNA synthesis and suggest that ribonucleotide reductases may not be essential to the bacterial cell cycle nor are they necessarily part of a minimal bacterial genome.

Amino Acids↗

Bacillus anthracis virulent plasmid pX02 genes found in large plasmids of two other Bacillus species.

In order to cause the disease anthrax, Bacillus anthracis requires two plasmids, pX01 and pX02, which carry toxin and capsule genes, respectively, that are used as genetic targets in the laboratory detection of the bacterium. Clinical, forensic, and environmental samples that test positive by PCR protocols established by the Centers for Disease Control and Prevention for B. anthracis are considered to be potentially B. anthracis until confirmed by culture and a secondary battery of tests. We report the presence of 10 genes (acpA, capA, capB, capC, capR, capD, IS1627, ORF 48, ORF 61, and repA) and the sequence for the capsule promoter normally found on pX02 in Bacillus circulans and a Bacillus species closely related to Bacillus luciferensis. Tests revealed these sequences to be present on a large plasmid in each isolate. The 11 sequences consistently matched to B. anthracis plasmid pX02, GenBank accession numbers AF188935.1, AE011191.1, and AE017335.3. The percent nucleotide identities for capD and the capsule promoter were 99.9% and 99.7%, respectively, and for the remaining nine genes, the nucleotide identity was 100% for both isolates. The presence of these genes, which are usually associated with the pX02 plasmid, in two soil Bacillus species unrelated to B. anthracis alerts us to the necessity of identifying additional sequences that will signal the presence of B. anthracis in clinical, forensic, and environmental samples.

Bacillus↗

Biofilm-spore response in Bacillus cereus and Bacillus subtilis during nutrient limitation.

This study aimed to trace the dynamics of biofilm formation by vegetative cells and endospores of Bacillus cereus DL5 and Bacillus subtilis 168. Counts of B. cereus DL5 and B. subtilis 168 vegetative cells and spores either attached to glass wool or, correspondingly, planktonic cells were determined by standard plate-counting methods. Results from this study highlighted the biofilm-forming potential of both spores and vegetative cells of two different Bacillus species. It was shown that once Bacillus spores had attached to a surface, the spores germinated under favorable (B. cereus DL5) and even unfavorable (B. subtilis 168) nutrient conditions, resulting in biofilms containing both spores and vegetative populations. Furthermore, it was suggested that vegetative B. cereus DL5 cells exhibited a low propensity for spore formation in attached and planktonic growth forms in nutrient-limited growth medium. By contrast, vegetative B. subtilis 168 cells readily formed spores in planktonic and attached microcosms when exposed to nutrient-limited growth conditions. Sporulation in attached Bacillus populations is an important practical consideration for many food industries, such as dairy processing, where bacilli are routinely isolated from populations attached to processing-equipment surfaces.

Bacillus cereus↗

[Cloning and gene expression of Bacillus cereus neutral proteinase in Bacillus subtilis cells].

The neutral proteinase gene of Bacillus cereus was cloned. Its restriction map and the direction of transcription was determined. It was shown that the neutral proteinase gene could be expressed in Bacillus cells. The thermostability of the product coded by the neutral proteinase gene and its natural analogue was explored. The obtained data indicate that the neutral proteinase of Bacillus cereus is closely related to the enzyme of Bacillus amyloliquefaciens by these parameters. It was found that the neutral proteinase of Bacillus cereus has a high sensitivity to autolysis and that leads to the decrease in the enzymes concentration in the cultural medium at the late stages of cell growth. But the possibility of stabilization the neutral proteinase by Ca2+ ions has been demonstrated.

Bacillus cereus↗

[The nature of the interrelations of different Bacillus thuringiensis serotypes between themselves and other species of the genus Bacillus].

Intraspecies interrelations between representatives of 7 serotypes of Bacillus thuringiensis, as well as antagonistic interrelations between B. thuringiensis and 130 strains of 16 species of Bacillus bacteria were studied. Antagonistic activity was determined for 18 strains, representatives of genus Bacillus, with respect to B. thuringiensis var. tuviensis. Antagonism was the most pronounced between the strains of the alesti serotype and representatives of other serotypes as well as between the strains V. thuringiensis var. tuviensis and most of other bacillus species. Strain B. thuringiensis var. tuviensis is slightly sensitive to the action of toxic metabolites from strains of this and other species of genus Bacillus.

Antibiosis↗

Molecular cloning of a subtilisin J gene from Bacillus stearothermophilus and its expression in Bacillus subtilis.

The structural gene for a subtilisin J from Bacillus stearothermophilus NCIMB10278 was cloned in Bacillus subtilis using pZ124 as a vector, and its nucleotide sequence was determined. The nucleotide sequence revealed only one large open reading frame, composed of 1,143 base pairs and 381 amino acid residues. A Shine-Dalgarno sequence was found 8 bp upstream from the translation start site (GTG). The deduced amino acid sequence revealed an N-terminal signal peptide and pro-peptide of 106 residues followed by the mature protein comprised of 275 residues. The productivity of subtilisin in the culture broth of the Bacillus subtilis was about 46-fold higher than that of the Bacillus stearothermophilus. The amino acid sequence of the extracellular alkaline protease subtilisin J is highly homologous to that of subtilisin E and it shows 69% identity with subtilisin Carlsberg, 89% with subtilisin BPN' and 70% with subtilisin DY. Some properties of the subtilisin J that had been purified from the Bacillus subtilis were examined. The subtilisin J has alkaline pH characteristics and a molecular weight of 27,500. It retains about 50% of its activity even after treatment at 60 degrees C for 30 min in the presence of 2 mM calcium chloride.

Amino Acid Sequence↗

Seasonal occurrence of psychrotrophic Bacillus species in raw milk, and studies on the interactions with mesophilic Bacillus sp.

Mesophilic and psychrotrophic isolates of Bacillus species displayed seasonal incidences in raw and pasteurised milk. The incidence of mesophilic isolates was highest in the winter and lowest in the summer/autumn while pschrotroph incidence was conversely lowest in the winter and highest in the late summer/autumn. Spores of Bacillus sp. were isolated from raw milk taken from farm milk machines and bulk tanks, milk tankers, diary silos and pasteurised milk. A consistent seasonal fluctuation in incidence throughout these samples suggested that spores of Bacillus sp. derived from the farm environment survived as important contaminants right through the milk chain to the pasteurised product. Up to seven mesophilic Bacillus sp. were isolated from a single sample with three species commonly occurring in most samples. The predominant mesophilic species isolated were B. pumilus, B. licheniformis and B. subtilis. The dominant psychrotrophic isolate was B. cereus. Selected mesophilic isolates were examined for possible antagonistic effects on the growth of psychrotropic B. cereus and B. pumilus isolates. Bacillus subtilis and B. licheniformis were found to produce antagonistic factors. It was considered that these factors may influence the incidence and growth of psychrotrophic isolates in the farm environment or in milk but the factors are not yet fully characterised or identified.

Animals↗

Re-identification of the halotolerant, biosurfactant-producing Bacillus licheniformis strain JF-2 as Bacillus mojavensis strain JF-2.

Bacillus strain JF-2 (ATCC 39307) is a halotolerant, biosurfactant-producing bacterium that was initially described as a member of the species Bacillus licheniformis based on a limited set of phenotypic characteristics. Here, genetic and phenotypic analyses were employed to determine the relationship of Bacillus strain JF-2 to other Bacillus strains. The restriction patterns with AluI and analysis of gyrA and 16S rRNA gene sequences grouped Bacillus strain JF-2 with B. mojavensis(T) and not with B. licheniformis(T). DNA-DNA similarity showed JF-2 was 75% similar to B. mojavensis(T) and only 11% similar to B. licheniformis(T). Both strain JF-2 and B. mojavensis(T) required DNA for anaerobic growth, but B. licheniformis(T) did not. B. mojavensis(T) and strain JF-2 did not grow anaerobically in thioglycollate medium or aerobically with propionate while B. licheniformis(T) grew under these conditions. DNA-DNA similarity, gene sequence data and phenotypic characteristics all support the assignment of JF-2 as a member of the species B. mojavensis.

Anaerobiosis↗

Isolation and characterization of Bacillus sp. BP-6 LipA, a ubiquitous lipase among mesophilic Bacillus species.

AIMS: The aim of this study was to perform the isolation, cloning and characterization of a lipase from Bacillus sp. BP-6 bearing the features of a biotechnologically important group of enzymes. METHODS AND RESULTS: Strain Bacillus sp. BP-6, showing activity on tributyrin plates, was used for isolation of lipase-coding gene lipA by means of inverse and direct PCR. The complete 633 nucleotide ORF isolated was cloned in Escherichia coli for further characterization. The amino acid sequence of the cloned protein was 98% identical to B. subtilis and B. megaterium lipases, the enzyme also showing similar molecular and biochemical features. CONCLUSIONS: The gene coding for Bacillus sp. BP-6 LipA was found in all mesophilic Bacillus species assayed, indicating its ubiquity in the genus. The cloned enzyme displayed the same properties as those of homologous lipases. SIGNIFICANCE AND IMPACT OF THE STUDY: The overall profile of Bacillus sp. BP-6 LipA was found to be that of a ubiquitous and highly conserved subfamily I.4 bacterial lipase. Previously described lipases within this family have shown to be well suited for biotechnological applications, suggesting that the cloned enzyme could be used accordingly.

Bacillus↗

Gracilibacillus gen. nov., with description of Gracilibacillus halotolerans gen. nov., sp. nov.; transfer of Bacillus dipsosauri to Gracilibacillus dipsosauri comb. nov., and Bacillus salexigens to the genus Salibacillus gen. nov., as Salibacillus salexigens comb. nov.

A Gram-positive, extremely halotolerant bacterium was isolated from the Great Salt Lake, Utah, USA. The strain, designated NNT (= DSM 11805T), was strictly aerobic, rod-shaped, motile by peritrichous flagella and spore-forming. Strain NNT grew at salinities of 0-20% (w/v) NaCl. A distinctive feature of strain NNT was its optimal growth in salt-free medium. The polar lipid pattern of strain NNT consisted of phosphatidyl glycerol, diphosphatidyl glycerol and two phospholipids of unknown structure. The G + C content of its DNA was 38 mol%. The morphological, physiological and, particularly, the 16S rDNA sequence data, showed that strain NNT was associated with 'Bacillus group 1'. However, the organisms showing the greatest degree of sequence similarity to strain NNT were members of the genus Halobacillus and the species Marinococcus albus, Virgibacillus pantothenticus, Bacillus salexigens and Bacillus dipsosauri. On the basis of chemotaxonomic data, strain NNT was shown to be chemically most similar to B. salexigens and B. dipsosauri, with the greatest degree of similarity being shown to the latter organism. This was consistent with the 16S rDNA sequence data. Members of the genus Halobacillus comprise a chemically distinct group and can easily be distinguished from all other organisms of 'Bacillus group 1'. On the basis of the 16S rDNA data, chemotaxonomy and the physiology of strain NNT, it is proposed that this organism is a member of a new species, within a new genus, for which the name Gracilibacillus halotolerans is proposed. It is also proposed that B. dipsosauri be transferred to this genus as Gracilibacillus dipsosauri comb. nov. and that B. salexigens be transferred to the genus Salibacillus gen. nov., as Salibacillus salexigens comb. nov. Finally, additional data is provided to support the transfer of Bacillus pantothenticus to the genus Virgibacillus, as Virgibacillus pantothenticus Heyndrickx et al. (1998).

Bacillus↗