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Characterization of plasmid pAW63, a second self-transmissible plasmid in Bacillus thuringiensis subsp. kurstaki HD73.

Bacillus thuringiensis subspecies kurstaki HD73, toxic for lepidopteran larvae, contains two large self-transmissible plasmids of approximately 75 kb, pHT73 and pAW63. The conjugative plasmid pHT73 has been studied extensively and has been shown to harbour the toxin gene cry1Ac, the transposon Tn4430 and several insertion sequences. In this study it was demonstrated that the minor plasmid pAW63 is also self-transmissible and about 10-30 times more efficient in mobilizing plasmid pBC16. To facilitate direct selection for pAW63 transfer, the plasmid was tagged with the tetracycline resistance transposon Tn5401 and in intraspecies matings it was found that after 2 h, all recipients had acquired a copy of the plasmid. Mating experiments demonstrated that pAW63 could be transferred to Bacillus thuringiensis subsp. israelensis, Bacillus cereus, Bacillus licheniformis, Bacillus subtilis and Bacillus sphaericus, and that the conjugative functions were expressed in these hosts. Hybridization studies showed that the replicons of pAW63 and pHT73 were distinct from one another. Sequences homologous to transposon Tn4430 and several insertion sequences were, however, shown to reside on both plasmids.

Bacillus↗

Inhibition of Bacillus anthracis and potential surrogate bacilli growth from spore inocula by nisin and other antimicrobial peptides.

The ability of nisin, synthetic temporin analogs, magainins, defensins, and cecropins to inhibit Bacillus anthracis, Bacillus cereus, Bacillus thuringiensis, Bacillus mycoides, and Bacillus subtilis growth from spore inocula was determined using well diffusion assays. Nisin, magainin II amide, and defensins were inhibitory in screening against B. anthracis Sterne or B. cereus ATCC 7004, but only nisin inhibited virulent B. anthracis strains. The MICs of nisin against the 10 Bacillus strains examined were 0.70 to 13.51 microg/ml. Synthetic temporin analogs also inhibited B. anthracis but were not as potent as nisin. None of the strains examined were appropriate B. anthracis surrogates for testing sensitivity to antimicrobial peptides.

Anti-Bacterial Agents↗

[Cloning and expression in Escherichia coli of oligo-1,6-glucosidase gene from Bacillus subtilis HB002].

The gene coding for oligo-1,6-glucosidase of Bacillus subtilis HB002 was cloned by the shotgun-cloning method and sequenced by the chain-termination method of Sanger et al. It consists of an open reading frame of 1683 bp. The amino acid sequence of oligo-1,6-glucosidase deduced from its nuecleotide sequence predicts a protein of 561 amino acid residues with a Mr of 65.985 kD, which is 81% and 67% identical to those of oligo-1,6-glucosidase from Bacillus sp. and Bacillus coagulans, respectively, 89% and 79% similar to those of oligo-1,6-glucosidase from Bacillus sp. and Bacillus coagulans, respectively. The oligo-1,6-glucosidase gene of Bacillus subtilis HB002 was cloned into Escherichia coli expression plasmid pBV220, the result of SDS-PAGE showed that the oligo-1,6-glucosidase gene had been expressed in Escherichia coli DH5 alpha, the expressed oligo-1, 6-glucosidase has enzymatic activity.

Amino Acid Sequence↗

Characterization of Bacillus spore species and their mixtures using postsource decay with a curved-field reflectron.

A strategy is proposed for the rapid identification of Bacillus spores, which relies on the selective release of a family of proteins, referred to as small, acid-soluble spore proteins (SASPs). In this work, SASPs were selectively solubilized from Bacillus spores on the MALDI sample plate by using 10% TFA. Proteolytic digests of SASPs generated in situ from spores of B. subtilis 168, B. globigii, B. thuringiensis subs. Kurstaki HD-1, B. cereus T, and the nonpathogenic strain B. anthracis Sterne were prepared in 5-25 min by using trypsin immobilized on Agarose beads and subsequently analyzed by MALDI-TOFMS using a curved-field reflectron. Protein identification was obtained by partial sequencing of distinctive tryptic peptides from Bacillus spores via post-source decay analysis combined with genome-based database searches by Mascot Sequence Query. Various unique SASPs were identified, allowing the characterization of Bacillus species by obtaining sequence-specific information on single peptides. The applicability of this approach for the rapid identification of Bacillus species was further established by analyzing spore mixtures.

Amino Acid Sequence↗

Atomic force microscopy of Bacillus spore surface morphology.

Bacillus spore surface morphology was imaged with atomic force microscopy (AFM) to determine if characteristic surface features could be used to distinguish between four closely related species; Bacillus anthracis Sterne strain, Bacillus thuringiensis var. kurstaki, Bacillus cereus strain 569, and Bacillus globigii var. niger. AFM surface height images showed an irregular topography across the curved upper surface of the spores. Phase images showed a superficial grain structure with different levels of phase contrast and significant differences in average surface morphologies among the four species. Although spores of the same species showed similarities, there was significant variability within each species. Overall, AFM revealed that spore surface morphology is rich with information, which can be used to distinguish a sample of about 20 spores from a similar number of spores of closely related species. Statistical analysis of spore morphology from a combination of amplitude and phase images for a small sample allows differentiation between, B. anthracis and its close relatives.

Bacillus↗

Serious infections caused by Bacillus species.

Thirty-eight patients with serious infections caused by organisms belonging to the genus Bacillus are described. Our experience, and that reported in the literature, indicates that, in most cases, isolated Bacillus bacteremia is not a particularly serious disease. Therefore, under most circumstances, empiric antibiotic therapy designed specifically for treatment of Bacillus is probably not necessary. Endocarditis can occur, but apparently follows bacteremia only infrequently. When these bacteria cause localized infection such as pneumonia, pan-ophthalmitis, visceral abscess, or musculoskeletal infections, tissue necrosis and profound morbidity are the rule. The frequency of these complications following bacteremia appears to be low but cannot be estimated from our experience or that reported in the literature reviewed. The role of intravascular devices and trauma as predisposing factors is emphasized. Immunocompromised hosts and intravenous drug abusers appear predisposed, but intravascular devices in the former group may play an important role in the pathogenesis of Bacillus infections. Antibiotics which appear especially useful in the treatment of Bacillus infections are clindamycin and vancomycin, to which the vast majority of strains are susceptible in vitro. Beta-lactam antibiotics, including the new cephalosporins and penicillins, are of little value in this setting.

Adult↗

Significant passive protective effect against anthrax by antibody to Bacillus anthracis inactivated spores that lack two virulence plasmids.

The protective-antigen (PA)-based cell-free vaccine is the only vaccine licensed for use against Bacillus anthracis infection in humans. Although the PA shows strong immunogenicity, the capsule or spore-associated somatic antigens may be important as additional vaccine targets for full protection against anthrax. In this study, the protective effect of spore-associated antigens against B. anthracis infection was determined. Rabbits were immunized with formalin-fixed spores of a non-toxigenic unencapsulated B. anthracis strain that lacked the two virulence plasmids pXO1 and pXO2, and the protective effects of the immune antibody were evaluated. Immunostaining and Western blot analysis revealed that the anti-B. anthracis (anti-BA)-spore IgG specifically bound to the surface of spores or endospores of B. anthracis, but not to vegetative cells, or closely related Bacillus species, such as Bacillus cereus, Bacillus subtilis and Bacillus thuringiensis. Passively transferred anti-BA-spore IgG protected mice from intraperitoneal challenge with a lethal dose of fully virulent B. anthracis spores, and increased the survival rate in a dose-dependent manner. Pre-incubation of spores with antibody also reduced their infectivity in a dose-dependent manner. The number of bacteria (c.f.u.) in spleens and livers of infected mice was significantly lower in antibody-treated mice than in untreated mice. Treatment with anti-BA-spore IgG also inhibited the germination of spores in J774.1 macrophages, suggesting that opsonization of spores promotes phagocytosis and subsequent killing by macrophages. These results indicate the usefulness of spore surface antigens as vaccine targets. In combination with major virulence factors such as the PA, spore-associated antigens may offer a safer and more effective multicomponent vaccine for B. anthracis infection.

Animals↗

Antimicrobial activity determined in strains of Bacillus circulans cluster.

Wild-type strains of the genus Bacillus were screened for antimicrobial activity. Two strains exhibited antimicrobial activity against Micrococcus luteus and were identified as Bacillus polymyxa MIR-23 and Bacillus circulans MIR-13. Bacillus polymyxa MIR-23 was active against Escherichia coli, Pseudomonas aeruginosa and Aspergillus niger, whereas Bacillus circulans MIR-13 did not show activity against these microorganisms. Bacillus subtilis ATCC 6633 and B. polymyxa ATCC 10401 were used as standard antibiotic-producer strain and showed different antimicrobial profiles and yields from B. polymyxa MIR-23. The different antimicrobial profile of the two selected strains could possibly be used as a taxonomic marker.

Anti-Bacterial Agents↗

Protection of oilseed rape (Brassica napus) toward fungal pathogens by strains of plant-associated Bacillus amyloliquefaciens.

In this report, four Bacillus strains were tested for effects on plant fitness and disease protection of oilseed rape (Brassica napus). The strains belonged to newly discovered plant-associated Bacillus amyloliquefaciens and a recently proposed species, Bacillus endophyticus. The fungal pathogens tested represented different infection strategies and included Alternaria brassicae, Botrytis cinerea, Leptosphaeria maculans, and Verticillium longisporum. The B. amyloliquefaciens strains showed no or a weak plant growth promoting activity, whereas the B. endophyticus strain had negative effects on the plant as revealed by phenological analysis. On the other hand, two of the B. amyloliquefaciens strains conferred protection of oilseed rape toward all pathogens tested. In vitro experiments studying the effects of Bacillus exudates on fungal growth showed clear growth inhibition in several but not all cases. The protective effects of Bacillus can therefore, at least in part, be explained by production of antibiotic substances, but other mechanisms must also be involved probably as a result of intricate plant-bacteria interaction. The protective effects observed for certain Bacillus strains make them highly interesting for further studies as biocontrol agents in Brassica cultivation.

Bacillus↗

Aerobic nitrification-denitrification by heterotrophic Bacillus strains.

Twenty-four Bacillus strains predominantly outgrown in a night soil treatment system were isolated and characterized. Under various culture conditions, cell interactions took place among them and cell population changed. Maximum removal of NH4+-N and cell production by the isolates occurred under the conditions of 30% DO and C/N ratio of 8. Five dominant isolates were identified to be species of Bacillus cereus, Bacillus subtilis and Bacillus licheniformis with similarities of 78-94%. Additions of 0.8% peptone and 0.3% yeast extract to a basal medium influenced the growth of isolates and the removal of NH4+-N in flask culture. Metal ions such as Ca2+, Fe2+ and Mg2+ had a similar effect. The specific growth rates of the five isolates were found to be in a range of 0.43-0.55 h(-1). During the flask experiment of nitrogen removal under aerobic growth conditions, active nitrification by the isolates occurred largely in 1h with a decrease of COD and alkalinity reduced to only 74.6% of theoretical value. From the nitrogen balance, the percentage of nitrogen lost in the flask culture was estimated to be 33.0%, which was presumed to convert to N2 gas. This conversion of ammonia to N2 without formation of nitrous oxide under aerobic growth conditions was confirmed by GC analysis. From all the results, it has been found that the Bacillus strains were able to occur simultaneously aerobic nitrification/denitrification and the B3 process using the Bacillus strains seemed to possess some economic advantages.

Aerobiosis↗

Decolourisation and detoxification of synthetic molasses melanoidins by individual and mixed cultures of Bacillus spp.

The decolourisation of synthetic melanoidins (i.e., GGA, GAA, SGA, and SAA) by three Bacillus isolates (Bacillus thuringiensis (MTCC 4714), Bacillus brevis (MTCC 4716) and Bacillus sp. (MTCC 6506)) was studied. Significant reduction in the values of physicochemical parameters was noticed alongwith the decolourisation of all four melanoidins (10% v/v). B. thuringiensis (MTCC 4714) caused maximum decolourisation followed by B. brevis (MTCC 4716) and Bacillus sp. (MTCC 6506). A mixed culture comprised of these three strains was capable of decolourising all four melanoidins. The medium that contained glucose as a sole carbon source showed 15% more decolourisation than that containing both carbon and nitrogen sources. Melanoidin SGA was maximally decolourised (50%) while melanoidin GAA was decolourised least ( approximately 06%) in the presence of glucose as a sole energy source. The addition of 1% glucose as a supplementary carbon source was essential for co-metabolism of melanoidin complex. The decolourisation of synthetic melanoidin by three Bacillus spp. significantly reduced the toxicity to the tubificid worm (Tubifex tubifex, Müller).

Analysis of Variance↗

Antimicrobial activities of human beta-defensins against Bacillus species.

Natural defences in the human body function to protect us from numerous environmental toxins and exposure to potential harmful biological agents. An important frontline defence is antimicrobial peptides. These peptides occur at environmental interfaces and serve to limit bacterial invasion. There has been little work comparing specific peptides as potential antimicrobial compounds. In this study, we evaluated the antimicrobial activity of peptides from the human beta-defensin (HBD) family against four species of Bacillus, chosen as models for Bacillus anthracis, a potential bioweapon. The impact of peptide concentration, sequence and protein binding was evaluated on their biological activity. The results indicated that HBD-3 was the most biologically active against Bacillus subtilis and Bacillus licheniformis, whilst HBD-2 was found to be most active against Bacillus cereus and Bacillus thuringiensis. Moreover, the antimicrobial activity of the peptides was directly related to peptide concentration and indirectly related to albumin concentration (i.e. protein binding).

Amino Acid Sequence↗

The comparative ability of four isolates of Bacillus subtilis to ferment soybeans into dawadawa.

In an attempt to develop starter cultures for fermenting soybeans into the traditional West African condiment dawadawa, four isolates of Bacillus subtilis: 24BP(2), 72RP(17), 72BP(30), and FpdBP(2), which had been selected from 42 Bacillus cultures in a previous study by the current authors, were used separately to produce soy-dawadawa. The accompanying microbiological and biochemical changes, including enzymatic activities, as well as the organoleptic quality of the products were evaluated including that of a control sample which was fermented spontaneously. Significant differences existed in the ability of the four isolates to hydrolyse the soybean proteins, starch, and fat to produce dawadawa. Bacillus subtilis 24BP(2) recorded the highest protease and amylolytic activities, 101 U/ml and 26.68 mg/ml, respectively, and liberated the most amino acids, 117.64 mg/g dry wt., during fermentation. Bacillus subtilis 24BP(2) also grew to the highest population of cells in the final product. Taste panelists found soybean dawadawa produced by each of the four isolates acceptable and rated soup flavoured with soy-dawadawa produced by Bacillus subtilis FpdBP(2) as the best sample. Panelists scored it higher than the control sample and soy-dawadawa produced by Bacillus subtilis 24BP(2) in that order.

Bacillus subtilis↗

Genetic relationship among Bacillus licheniformis rolling-circle-replicating plasmids and complete nucleotide sequence of pBL63.1, an atypical replicon.

The degree of biodiversity among Bacillus licheniformis plasmids and their relation to other Bacillus subtilis group plasmids has been evaluated. To attain this goal we surveyed the diversity and linkage of replication modules in a collection of 21 naturally occurring plasmids of B. licheniformis strains, isolated from different geographical areas. On the basis of rep gene sequence analysis it was possible to group the B. licheniformis plasmids rep genes in two main cluster. Comparison with known rep genes from Bacillus rolling-circle-replicating (RCR) plasmids revealed the presence in B. licheniformis plasmids of replication genes with a DNA sequence peculiar to B. licheniformis species together with rep genes with a very high sequence similarity to B. subtilis plasmids. Furthermore, the molecular organization of an atypical replicon, pBL63.1, was shown. This plasmid did not display any significant similarity with known Bacillus RCR plasmids. The complete nucleotide sequence evidenced a replication module with an unexpected similarity with Rep proteins from RCR plasmids of bacterial species phylogenetically distantly related to Bacillus. pBL63.1 represents an exception to the low-level diversity hypothesis among Bacillus RC replicons.

Bacillus↗

Small rolling circle plasmids in Bacillus subtilis and related species: organization, distribution, and their possible role in host physiology.

Bacillus subtilis and related species (Bacillus licheniformis, Bacillus pumilus, Bacillus amyloliquefaciens, and Bacillus mojavensis) represent a group of bacteria largely studied and widely employed by industry. Small rolling circle replicating plasmids of this group of bacteria have been intensively studied as they represent a convenient model for genetic research and for the construction of molecular tools for the genetic modification of their hosts. Through the computational analysis of the available plasmid sequences to date, the first part of this review focuses on the main stages that the present model for rolling circle replication involves, citing the research data which helped to elucidate the mechanism by which these molecules replicate. Analysis of the distribution and phylogeny of the small RC plasmids inside the Bacillus genus is then considered, emphasizing the low level of diversity observed among these plasmids through the in silico analysis of their organization and the sequence divergence of their replication module. Finally, the parasitic vs. mutualistic nature of small rolling circle plasmids is briefly discussed.

Bacillus subtilis↗

Removal of 2,4-dichlorophenol by suspended and immobilized Bacillus insolitus.

In this experiment, Bacillus insolitus was isolated and selected from a mixed culture that have been acclimated to chlorophenols. Decomposition of chlorophenolic compounds will be studied using this pure culture in both suspended and immobilized form. The results are: at lower initial concentrations of 2,4-dichlorophenol (10-50 mg/l), immobilized Bacillus insolitus shows a higher removal of 2,4-dichlorophenol than Bacillus insolitus in suspended growth. When the 2,4-dichlorophenol concentration becomes higher (50-200 mg/l), both immobilized and suspended Bacillus insolitus have approximately the same efficiency for removal of 2,4-dichlorophenol. Higher concentrations of 2,4-dichlorophenol are inhibitive to the growth of either suspended or immobilized Bacillus insolitus. At lower concentrations of 2,4-dichlorophenol, immobilized mixed culture may have the same removal efficiency of 2,4-dichlorophenol as immobilized pure culture of Bacillus insolitus. But with regard to the overall 2,4-dichlorophenol removal efficiency, immobilized pure culture is considered to be superior to immobilized mixed culture.

Bacillus↗

Clinical profile and outcome in Bacillus endophthalmitis.

OBJECTIVE: To study the clinical presentation, microscopic and organismal culture correlation of vitreous, and species-specific outcome in Bacillus endophthalmitis DESIGN: Retrospective noncomparative case series. INTERVENTION: Thirty-one culture proven Bacillus endophthalmitis patients between January 1991 and February 1998 underwent vitrectomy and intravitreal antibiotic injection. Lensectomy was combined when considered essential, and on a few occasions intravitreal dexamethasone was added. The patients also received topical and systemic antibiotics. The undiluted vitreous biopsy was the source for microbiologic evaluation (microscopy and culture sensitivity). MAIN OUTCOME MEASURES: The duration of symptoms, the presenting visual acuity, and influence of intravitreal dexamethasone with intravitreal antibiotics were examined for any statistical correlation with the final visual acuity. RESULTS: Trauma was the major cause of infection. Vitreous biopsy microscopy demonstrated gram-positive bacillus in 28 of 31 cases, and polymicrobial infection was seen in 12 instances. All Bacillus species were sensitive to gentamicin, followed by vancomycin and ciprofloxacin. Clinical treatment within 7 days of symptoms, use of intravitreal vancomycin, and absence of polymicrobial infection were associated with better visual outcome. CONCLUSIONS: With appropriate treatment that essentially consists of vitrectomy and intravitreal antibiotics, patients with Bacillus endophthalmitis are likely to benefit in many instances. Gram-positive bacilli detected on vitreous microscopy should be empirically treated as Bacillus species unless otherwise proved.

Adolescent↗

Evaluation of ribosomal RNA gene restriction patterns for the classification of Bacillus species and related genera.

AIMS: To identify Bacillus species and related genera by fingerprinting based on ribosomal RNA gene restriction patterns; to compare ribosomal RNA gene restriction patterns-based phylogenetic trees with trees based on 16S rRNA gene sequences; to evaluate the usefulness of ribosomal RNA gene restriction patterns as a taxonomic tool for the classification of Bacillus species and related genera. METHODS AND RESULTS: Seventy-eight bacterial species which include 42 Bacillus species, 31 species from five newly created Bacillus-related genera, and five species from five phenotypically related genera were tested. A total of 77 distinct 16S rRNA gene hybridization banding patterns were obtained. The dendrogram resulting from UPGMA analysis showed three distinct main genetic clusters at the 75% banding pattern similarity. A total of 77 distinct 23S and 5S rRNA genes hybridization banding patterns were obtained, and the dendrogram showed four distinct genetic clusters at the 75% banding pattern similarity. A third dendrogram was constructed using a combination of the data from the 16S rRNA gene fingerprinting and the 23S and 5S rRNA genes fingerprinting. It revealed three distinct main phylogenetic clusters at the 75% banding pattern similarity. CONCLUSIONS: The Bacillus species along with the species from related genera were identified successfully and differentiated by ribosomal RNA gene restriction patterns, and most were distributed with no apparent order in various clusters on each of the three dendrograms. SIGNIFICANCE AND IMPACT OF THE STUDY: Our data indicate that ribosomal RNA gene restriction patterns can be used to reconstruct the phylogeny of the Bacillus species and derived-genera that approximates, but does not duplicate, phylogenies based on 16S rRNA gene sequences.

Bacillus↗