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Construction and one-step purification of Bacillus kaustophilus leucine aminopeptidase fused to the starch-binding domain of Bacillus sp. strain TS-23 alpha-amylase.

The starch-binding domain of Bacillus sp. strain TS-23 alpha-amylase was introduced into the C-terminal end of Bacillus kaustophilus leucine aminopeptidase (BkLAP) to generate a chimeric enzyme (BkLAPsbd) with raw-starch-binding activity. BkLAPsbd, with an apparent molecular mass of approximately 65 kDa, was overexpressed in Escherichia coli M15 cells and purified to homogeneity by nickel-chelate chromatography. Native PAGE and chromatographic analyses revealed that the purified fusion protein has a hexameric structure. The half-life for BkLAPsbd was 12 min at 70 degrees C, while less than 20% of wild-type enzyme activity retained at the same heating condition. Compared with the wild-type enzyme, the 60% decrease in the catalytic efficiency of BkLAPsbd was due to a 91% increase in K (m) value. Starch-binding assays showed that the K (d) and B (max) values for the fusion enzyme were 2.3 microM and 0.35 micromol/g, respectively. The adsorption of the crude BkLAPsbd onto raw starch was affected by starch concentration, pH, and temperature. The adsorbed enzyme could be eluted from the adsorbent by 2% soluble starch in 20 mM Tris-HCl buffer (pH 8.0). About 49% of BkLAPsbd in the crude extract was recovered through one adsorption-elution cycle with a purification of 11.4-fold.

Bacillus↗

Screening of Bacillus strains as potential probiotics and subsequent confirmation of the in vivo effectiveness of Bacillus subtilis MA139 in pigs.

A total of 124 samples were collected from the intestine of broiler chickens, piglet faeces, fermented foods, soils and Chinese herbs. More than 750 strains of aerobic, spore-forming bacteria were isolated from these samples. The inhibitory activity of these spore-forming strains against Escherichia coli K88, E. coli K99, Salmonella typhimurium and Staphylococcus aureus was assessed using a disc plate diffusion assay. The six bacilli with the largest inhibition zones against the four indicator bacteria were chosen and assessed for their resistance to unfavorable conditions within simulated gut environments. The strain Bacillus subtilis MA139 showed full resistance to pH 2, 0.3% bile salts and exhibited the highest antimicrobial activity. Based on these results, B. subtilis MA139 was selected as a potential probiotic and fed to piglets at concentrations of 2.2 x 10(5), 2.2 x 10(6) or 2.2 x 10(7) CFU/g of feed during a 28-day feeding trial. A negative control consisting of the basal diet with no additives and a positive control consisting of the basal diet supplemented with 16 g/ton flavomycin were also included. Ninety piglets between 35 and 40 days old were used in the in vivo animal trials. B. subtilis MA139 enhanced daily gain (P = 0.10) and feed conversion (P = 0.03) compared with the negative control. The performance of pigs fed B. subtilis MA139 supplemented diets did not differ from that of pigs fed the antibiotic diet. There was a significant increase in Lactobacilli cell counts (P = 0.02) and a numerical decrease in E. coli counts (P = 0.05) in the faecal samples of pigs fed B. subtilis MA139 with 2.2 x 10(5) CFU/g of feed. The overall results of this study show that the use of initial co-culture with indicator pathogens, a disc plate diffusion assay and simulated gut environment tolerance tests is one of effective methods of screening Bacillus for probiotic use and that B. subtilis MA139 is a promising alternative to antibiotics for use as a feed additive in piglet diets.

Acids↗

DNA polymerase from mesophilic and thermophilic bacteria. III. Lack of fidelity in the replication of synthetic polydeoxyribonucleotides by DNA polymerase from Bacillus licheniformis and Bacillus stearothermophilus.

1. DNA polymerase from the mesophile Bacillus licheniformis and the thermophile Bacillus stearothermophilus has been used to study the replication of poly(dA-dT)-poly(dA-dT) and poly(dC)-poly(dG) templates at 37, 45, and 55 degrees C. 2. Incorporation of non-complementary deoxyribonucleoside triphosphates (misincorporation) occurred with both enzymes and both templates. Non-specific incorporation (de novo polynucleotide synthesis, random attachment to existing strands, and tritium exchange of nucleotides) accounted for, at most, a small fraction of the total observed misincorporation. The error rates at 37 degrees C for the complete system were as follows:: B. licheniformis: dATP, 1/61; dCTP, 1/830; dGTP, 1/360; dTTP, 1/65; B. stearothermophilus: dATP, 1/68; dCTP, 1/1430; dGTP, 1/440; dTTP, 1/67. For both organisms, the error rate for dCTP and dGTP was independent of incubation temperature; the error rate for dATP and dTTP was 5-50-fold greater than that for dCTP or dGTP and increased significantly from 37 to 55 degrees C. 3. The ratio of dATP to dTTP incorporation with the poly(dA-dT)-poly-(dA-dT) template was independent of temperature and close to unity. The ratio of dCTP to dGTP incorporation with the poly(dC)-poly(dG) template decreased from approx. 0.2 to 0.05 for the mesophile and from approx. 0.06 to 0.03 for the thermophile as the temperature increased from 37 to 55 degrees C.

Bacillus↗

Scanning force microscopy studies of the S-layers from Bacillus coagulans E38-66, Bacillus sphaericus CCM2177 and of an antibody binding process.

In many prokaryotic cells (eubacteria and archaebacteria) the outermost cell envelope component is composed of a regularly structured protein surface layer (S-layer). The two-dimensional S-layer from Bacillus coagulans E38-66 and Bacillus sphaericus CCM2177 has been investigated by SFM at molecular resolution under physiological conditions (i.e., in buffer solution). We find the E38-66 S-layer lattice to be oblique with lattice parameters of a = 9-10 nm, b = 7-8 nm and gamma = 80 degrees -90 degrees (E38-66). The CCM2177 lattice is square with a = 12-14 nm, in good agreement with TEM data. We have used the unique possibility of the SFM to study the kinematics of biological processes and have performed experiments on the adhesion of polyclonal antibodies to the recrystallized E38-66 protein layer on a time scale of about two to ten seconds per image frame. This represents a first step in directly visualizing molecular recognition reactions.

Antibodies, Bacterial↗

Cloning and sequencing of the genes encoding glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase and triosephosphate isomerase (gap operon) from mesophilic Bacillus megaterium: comparison with corresponding sequences from thermophilic Bacillus stearothermophilus.

The structural genes encoding glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 3-phosphoglycerate kinase (PGK) and the N-terminal part of triosephosphate isomerase (TIM) from mesophilic Bacillus megaterium DSM319 have been cloned as a gene cluster (gap operon) by complementation of an Escherichia coli gap amber mutant. Subsequently, the entire tpi gene, encoding TIM, was isolated by colony hybridization using a homologous probe. Nucleotide (nt) sequence analysis revealed an unidentified open reading frame (urf1) of 1029 bp located 50 nt upstream from the start codon of the gap gene. Gene expression from subclones containing different coding regions was studied by enzyme assay and SDS-PAGE. Both GAPDH and TIM are synthesized in transformed E. coli cells, whereas PGK is not. There is no unequivocal evidence for urf1 expression. Two putative promoter sites are present: one 100 nt upstream from urf1 and one 200 nt upstream from the pgk gene. An inverted repeat following the second promoter site is postulated to be involved in the transcriptional regulation of the operon. Each coding region shows a G+C content of 40% attained by the adaptation of the G+C content of the third base in the codon to compensate the G+C content of the first and second bases. The deduced amino acid (aa) sequences of B. megaterium GAPDH, PGK and TIM were compared with those from the thermophilic Bacillus stearothermophilus by antisymmetrical matrices. The detected characteristic thermophilic-mesophilic exchange pattern concerning aa substitutions between hydrophobic-polar and charged-charged residues corresponds to data obtained for thermophilic and mesophilic lactate dehydrogenases (LDH). The determination of the thermostability of these enzymes revealed two regions of stability for B. megaterium TIM at high enzyme concentrations. Heat treatment seems to be responsible for the conversion of two differently active conformations or the induction of a new quaternary structure.

Amino Acid Sequence↗

The clamp-loader-helicase interaction in Bacillus. Atomic force microscopy reveals the structural organisation of the DnaB-tau complex in Bacillus.

The clamp-loader-helicase interaction is an important feature of the replisome. Although significant biochemical and structural work has been carried out on the clamp-loader-clamp-DNA polymerase alpha interactions in Escherichia coli, the clamp-loader-helicase interaction is poorly understood by comparison. The tau subunit of the clamp-loader mediates the interaction with DnaB. We have recently characterised this interaction in the Bacillus system and established a tau(5)-DnaB(6) stoichiometry. Here, we have obtained atomic force microscopy images of the tau-DnaB complex that reveal the first structural insight into its architecture. We show that despite the reported absence of the shorter gamma version in Bacillus, tau has a domain organisation similar to its E.coli counterpart and possesses an equivalent C-terminal domain that interacts with DnaB. The interaction interface of DnaB is also localised in its C-terminal domain. The combined data contribute towards our understanding of the bacterial replisome.

Adenosine Triphosphatases↗

Isolation, purification and properties of new restriction endonucleases from Bacillus badius and Bacillus lentus.

We tentatively named two enzymes as BbaI and BleI, which were isolated and purified from Gram-positive mesophilic bacteria Bacillus badius 1458 and Bacillus lentus 1689 respectively, by ammonium sulphate precipitation, phosphocellulose and heparin-sepharose column chromatography. SDS-PAGE protein profiles for BbaI and BleI showed denatured molecular weights of 52 and 48 kDa, respectively. BbaI hydrolyzed pUC18 DNA into 1900 and 700 bp, pBR322 DNA into two fragments of 2800 and 1500 bp and Phix174 DNA into 3800 and 1600 bp. BleI hydrolyzed pUC18 DNA into 1800 and 800 bp, pBR322 DNA into two fragments of 2700 and 1600 bp and Phix174 DNA into 3700 and 1700 bp. The effects of temperature, ionic strength, pH and Mg2+ ion concentrations were studied to demonstrate some biochemical properties of BbaI and BleI. Maximum activities of these enzymes were observed at 37 degrees C (pH 8.0) with 100 mM NaCl and 10 mM Mg2+ concentrations.

Bacillus↗

Cloning and expression of a fibrinolytic enzyme (subtilisin DFE) gene from Bacillus amyloliquefaciens DC-4 in Bacillus subtilis.

A strong fibrinolytic enzyme produced by Bacillus amyloliquefaciens DC-4, subtilisin DFE, was isolated from douchi, a traditional Chinese soybean-fermented food. Based on the high homology between the N-terminal sequence of subtilisin DFE and that of subtilisin BPN, PCR primers were designed that allowed for the amplification and cloning of the intact subtilisin DFE gene. Sequence analysis indicated the presence of a 1149-bp open reading frame encoding 382 amino acid residues. The enzyme was actively expressed by the Escherichia coli-Bacillus subtilis shuttle expression vector pSUGV4 in the protease-deficient strain B. subtilis WB600, and its biochemical characteristics were the same as those of the original subtilisin DFE isolated from the donor strain, i.e., its molecular weight is approximately 28 kDa and it is a serine protease.

Amino Acid Sequence↗

Growth characteristics of Bacillus anthracis compared to other Bacillus spp. on the selective nutrient media Anthrax Blood Agar and Cereus Ident Agar.

Anthrax Blood Agar (ABA) and Cereus Ident Agar (CEI) were evaluated as selective growth media for the isolation of Bacillus anthracis using 92 B. anthracis and 132 other Bacillus strains from 30 species. The positive predictive values for the identification of B. anthracis on ABA, CEI, and the combination of both were 72%, 71%, and 90%, respectively. Thus, less than 10% of all species were misidentified using both nutrient media. Species which might be misidentified as B. anthracis were B. cereus, B. mycoides, and B. thuringiensis. Particularly, 30% of B. weihenstephanensis strains were misidentified as B. anthracis.

Agar↗

Stable integration and expression of mosquito-larvicidal genes from Bacillus thuringiensis subsp. israelensis and Bacillus sphaericus into the chromosome of Enterobacter amnigenus: a potential breakthrough in mosquito biocontrol.

Previously, we have successfully integrated a spectinomycin/streptomycin resistance gene into Enterobacter amnigenus strain An11, a potential host for mosquito control, using in vivo recombination via homologous recombination (An11S4::Omega). We now report the successful transfer of two mosquito-larvicidal genes, cry4B from Bacillus thuringiensis subsp. israelensis and binary toxin genes from Bacillus sphaericus, into the host genome. To facilitate the screening procedure, the E. amnigenus derivative, An11S4::Omega, was used as a host. The integration of both toxin genes by two successive crossover events interrupted the Omega region yielding two integrants designated An11S4::cry4B and An11S4::Omega::bin, respectively. Differences in the integration efficiency of these toxin genes were observed. The presence of both genes in the target sites of the host genome was verified by PCR. Cry4B was expressed weakly from An11S4::cry4B, but no expression of the binary toxin gene could be detected from An11S4::Omega::bin. Nevertheless, these two integrants exhibited mosquito-larvicidal activity against Aedes and Culex, suggesting that both proteins were expressed, but at very low levels.

Animals↗

Trimeric subunit stoichiometry of the glutamate transporters from Bacillus caldotenax and Bacillus stearothermophilus.

Catalysis of glutamate transport across cell membranes and coupling of the concentrative transport to sodium, proton, and potassium gradients are processes fundamental to organisms in all kingdoms of life. In bacteria, glutamate transporters participate in nutrient uptake, while in eukaryotic organisms, the transporters clear glutamate from the synaptic cleft. Even though glutamate transporters are crucial to the viability of many life forms, little is known about their structure and quaternary organization. In particular, the subunit stoichiometry of these polytopic integral membrane proteins has not been unequivocally defined. Determination of the native molecular mass of membrane proteins is complicated by their lability in detergent micelles and by their association with detergent and/or lipid molecules. Here we report the purification of glutamate transporters from Bacillus caldotenax and Bacillus stearothermophilus in a monodisperse, detergent-solubilized state. Characterization of both transporters either by chemical cross-linking and mass spectrometry or by size-exclusion chromatography and in-line laser light scattering, refractive index, and ultraviolet absorption measurements shows that the transporters have a trimeric quaternary structure. Limited proteolysis further defines regions of primary structure that are exposed to aqueous solution. Together, our results define the subunit stoichiometry of high-affinity glutamate transporters from B. caldotenax and B. stearothermophilus and localize exposed and accessible elements of primary structure. Because of the close amino acid sequence relationship between bacterial and eukaryotic transporters, our results are germane to prokaryotic and eukaryotic glutamate and neutral amino acid transporters.

Amino Acid Sequence↗

Clamp-loader-helicase interaction in Bacillus. Leucine 381 is critical for pentamerization and helicase binding of the Bacillus tau protein.

Recently, we revealed the architecture of the clamp-loader-helicase (tau-DnaB) complex in Bacillus by atomic force microscopy imaging and constructed a structural model, whereby a pentameric clamp-loader interacts with the hexameric helicase. Crucial to this model is the assumption that the clamp-loader forms a pentamer in the absence of other components of the clamp-loader complex such as deltadelta'. Here, we show that the Bacillus subtilis tau protein, even in the absence of deltadelta', interacts as a pentamer with the hexameric DnaB and that the L381 of tau is critical for the integrity of the tau oligomer and interaction with DnaB. The effects of the L381A mutation were confirmed by gel filtration, ultracentrifugation, circular dichroism, cross-linking studies, and genetic replacement of the dnaX gene with a mutant L381A dnaX gene in vivo. The L381A protein is able to support growth in vivo only when expressed in high quantities. Finally, despite the fact that a mutation at P465 has been reported to result in a thermosensitive gene in vivo, a P465L mutant protein interacts with DnaB in vitro suggesting that this defect is not a result of a defective tau-DnaB interaction.

Amino Acid Sequence↗

BpaI and BpnI: novel type II restriction endonucleases from Bacillus pasteurii and Bacillus pantothenticus.

Two novel type II restriction endonucleases, designated as BpaI and BpnI, were isolated from Bacillus pasteurii strain1761 and Bacillus pantothenticus strain1639, respectively. They were partially purified and SDS-PAGE indicated Mr values of 28 and 67 kDa for BpaI, 28 and 48 kDa for BpnI. The partially purified endonucleases hydrolyzed DNA into discrete fragments: pUC18 (2.6 kb for BpaI; 1.8 and 0.8 kb for BpnI), pBR322 (2.5 and 1.8 kb for BpaI; 2.6 and 1.7 kb for BpnI) and phix174 DNA (3.2 and 2.1 kb for BpaI; 4 and 1.3 kb for BpnI).

Bacillus↗

Improved translational efficiency of subtilisin YaB gene with different initiation codons in Bacillus subtilis and alkalophilic Bacillus YaB.

The ale gene specifying the subtilisin YaB produced by alkalophilic Bacillus YaB, has an unusual start codon UUG. Changing this codon to AUG and GUG increased expression of the ale gene in B. subtilis DB104 and in an ale deficient mutant strain YaB-DEC4. The relative translational efficiency order of the three initiation codons is AUG > GUG > UUG in B. subtilis DB104 and in YaB-DEC4. These data suggest that the preferred initiation codon is AUG for ale gene expression in Bacillus.

Bacillus subtilis↗

Nucleotide sequence of the Bacillus subtilis xylose isomerase gene: extensive homology between the Bacillus and Escherichia coli enzyme.

The xylose isomerase gene from Bacillus subtilis was cloned from a genomic BamH1 library by complementation of an isomerase defective Escherichia coli strain as previously described. The ATG initiation codon is preceded by a Shine-Dalgarno sequence and two hexamers being characteristic for the promoter region of Bacillus genes. The structural gene consists of 1320 base pairs, thus coding for a polypeptide chain of 440 amino acids with a molecular weight of 49 680. The polypeptide primary structure shows over 50% homology to that of the E. coli xylose isomerase.

Aldose-Ketose Isomerases↗

Bacillus curdlanolyticus sp. nov. and Bacillus kobensis sp. nov., which hydrolyze resistant curdlan.

Taxonomic characteristics of seven bacterial strains which were isolated from soil and hydrolyze resistant curdlan were studied. These bacteria were aerobic, spore-forming rods, contained menaquinone 7 as a major quinone, contained anteiso-C15:0 and iso-C16:0 as major cellular fatty acids, had guanine-plus-cytosine contents of 50 to 52 mol%, and could be divided into two groups on the basis of physiological and chemotaxonomic characteristics and DNA-DNA hybridization data. We propose the following two new species: Bacillus curdlanolyticus for strains YK9, YK121, YK161, YK201, and YK203, with type strain YK9 (= IFO 15724); and Bacillus kobensis for strains YK205 and YK207, with type strain YK205 (= IFO 15729).

Aerobiosis↗

Bacillus salexigens sp. nov., a new moderately halophilic Bacillus species.

Bacillus salexigens sp. nov. is proposed based on the characteristics of six moderately halophilic, grampositive, rod-shaped strains isolated from salterns and hypersaline soils located in different geographical areas of Spain. These strains were motile, formed endospores, were strictly aerobic, were catalase and oxidase positive, and contained peptidoglycan of the meso-diamlnopimelic acid type in their vegetative cell walls. The DNA base compositions of these strains ranged from 36.3 to 39.5 mol%, and these organisms constitute a homology group with levels of DNA-DNA homology ranging from 73 to 100%. The 16S rRNA sequence of strain C-20MoT, which was used as the representative strain of these isolates, groups with the 16S rRNA sequences of members of the genus Bacillus, and the highest level of similarity is 95.4%. The type strain is strain C-20Mo (= ATCC 700290 = DSM 11483 = CCM 4646).

Bacillus↗

PCR fingerprinting of whole genomes: the spacers between the 16S and 23S rRNA genes and of intergenic tRNA gene regions reveal a different intraspecific genomic variability of Bacillus cereus and Bacillus licheniformis [corrected].

Genomic diversity in 21 strains of Bacillus cereus and 10 strains of Bacillus licheniformis was investigated by random amplified polymorphic DNA (RAPD) analysis, which samples the whole genome, and by two PCR fingerprinting techniques sampling the hypervariable spacers between the conserved 16S and 23S rRNA genes of the rRNA gene operon (ITS-PCR) and regions between tRNA genes (tDNA-PCR). RAPD analysis showed a remarkable diversity among strains of B. cereus that was not observed with the rRNA and tRNA intergenic-spacer-targeted PCR, where all the strains showed practically identical fingerprints. A wide variability among the B. cereus strains was also observed in the plasmid profiles, suggesting that the genetic diversity within B. cereus species can arise from plasmid transfer. One contribution to the diversity detected by RAPD analysis was determined by the presence of large extrachromosomal elements that were amplified during RAPD analysis as shown by Southern hybridization experiments. In contrast to the strains of B. cereus, the 10 strains of B. licheniformis were grouped into two clusters which were the same with all the methods employed. The 16S rRNA genes were identical in all 10 strains when examined using single strand conformation polymorphism analysis after digestion with Alul and Rsal. From these data we hypothesize two different evolutionary schemes for the two species.

Bacillus cereus↗