Homology modeling and heterologous expression of highly alkaline subtilisin-like serine protease from Bacillus halodurans C-125

Here we report heterologous expression, enzymatic characterization and structure homology modeling of a subtilisin-like alkaline serine protease (ASP) from Bacillus halodurans C-125. Encoding gene was successfully obtained by PCR and cloned into pMA0911 shuttle vector under the control of strong HpaII promoter and expressed extracellularly. ASP enzyme was successfully expressed in B. subtilis WB800 cell line lacking eight extracellular proteases and produced extracellularly in the culture medium. Km, Vmax and specific activity parameters of the recombinantly produced ASP were identified as 0.2899 mg/ml, 76.12 U/ml and 9500 U/mg, respectively. The purified enzyme revealed remarkable proteolytic activity at highly alkaline conditions with a pH optimum 12.0 and notable thermostability with temperature optimum at 60 °C. Furthermore, substrate-free enzyme revealed remarkable pH stability at pH 12.0 and maintained 93% of its initial activity when incubated at 37 °C for 24 h and 60% of its initial activity upon incubation at 60 °C for 1 h. Theoretically calculated molecular mass of ASP protein was confirmed through SDS-PAGE and western blot analysis (Mw: 28.3 kDa). The secondary and tertiary structures of ASP protein were also identified through homology modeling and further examined in detail. ASP harbors a typical S8/S53 peptidase domain comprising 17 β-sheets and 9 α-helixes within its secondary structure. The structure dynamics analysis of modeled 3D structure further revealed that transient inactivating propeptide chain is the most dynamic region of ASP enzyme with 8.52 Ų β-Factor value. Additional residue-dependent fluctuation plot analysis also confirmed the elevated structure dynamics patterning of ASP N-terminus which could be the potential prerequisite for the autonomous propeptide removal of alkaline serine peptidases. Yet the functional domain of ASP becomes quite stable after autonomous exclusion of its propeptide. Although the sequence homology between ASP and commercial detergent additive B. lentus protease (PDB ID:1GCI) was moderate (65.4% sequence similarity), their overlaid 3D structures revealed much higher similarity (98.14%) within 0.80 Å RMSD. In conclusions, with remarkable pH stability, notable thermostability and particularly high specific activity at extreme alkaline conditions, the unveiled ASP protein stands out as a novel protease candidate for various industrial sectors such as textile, detergent, leather, feed, waste, pharmaceutical and others.

Bioremediation of cadmium polluted soil using a novel cadmium immobilizing plant growth promotion strain Bacillus sp. TZ5 loaded on biochar

Bioremediation of cadmium polluted soil using biochar (BC) and plant growth promotion bacteria (PGPB) have been widely concerned. In our study, a novel Cd immobilizing PGPB strain TZ5 was isolated based on the Cd immobilizing potential and plant growth promotion (PGP) traits. Further, changes of surface morphology and functional groups of TZ5 cells were observed after exposed to Cd²⁺ by SEM-EDS and FTIR analyses. Then, the strain TZ5 was successfully loaded on BC as biochemical composites material (BCM). Pot experiment indicated that the percentage of acetic acid-extractable Cd in BCM treatments significantly decreased by 11.34 % than control. Meanwhile, BCM significantly increased the dry weight of ryegrass by 77.78 %, and decreased the Cd concentration of ryegrass by 48.49 %, compared to control. Microbial counts and soil enzyme activities in rhizosphere were both significantly improved by BCM. Furthermore, the proportion of relative abundance of Bacillus genus was enhanced after treated by BCM, which indicated that the strain TZ5 was successfully colonized in the rhizosphere. This study provided a practical strategy for bioremediation of Cd contaminated soil.

Response surface method for polyhydroxybutyrate (PHB) bioplastic accumulation in Bacillus drentensis BP17 using pineapple peel

Polyhydroxybutyrate (PHB) is a biodegradable biopolymer which is useful for various applications including packing, medical and coating materials. An endospore-forming bacterium (strain BP17) was isolated from composted soil and evaluated for PHB production. Strain BP17, taxonomically identified as Bacillus drentensis, showed enhanced PHB accumulation and was selected for further studies. To achieve maximum PHB production, the culture conditions for B. drentensis BP17 were optimized through response surface methodology (RSM) employing central composite rotatable design (CCRD). The final optimum fermentation conditions included: pineapple peel solution, 11.5% (v/v); tryptic soy broth (TSB), 60 g/L; pH, 6.0; inoculum size, 10% (v/v) and temperature, 28°C for 36 h. This optimization yielded 5.55 g/L of PHB compared to the non-optimized condition (0.17 g/L). PHB accumulated by B. drentensis BP17 had a polydispersity value of 1.59 and an average molecular weight of 1.15x105 Da. Thermal analyses revealed that PHB existed as a thermally stable semi-crystalline polymer, exhibiting a thermal degradation temperature of 228°C, a melting temperature of 172°C and an apparent melting enthalpy of fusion of 83.69 J/g. It is evident that B. drentensis strain BP17 is a promising bacterium candidate for PHB production using agricultural waste, such as pineapple peel as a low-cost alternative carbon source for PHB production.

Structural analysis of the manganese transport regulator MntR from Bacillus halodurans in apo and manganese bound forms

The manganese transport regulator MntR is a metal-ion activated transcriptional repressor of manganese transporter genes to maintain manganese ion homeostasis. MntR, a member of the diphtheria toxin repressor (DtxR) family of metalloregulators, selectively responds to Mn²⁺ and Cd²⁺ over Fe²⁺, Co²⁺ and Zn²⁺. The DtxR/MntR family members are well conserved transcriptional repressors that regulate the expression of metal ion uptake genes by sensing the metal ion concentration. MntR functions as a homo-dimer with one metal ion binding site per subunit. Each MntR subunit contains two domains: an N-terminal DNA binding domain, and a C-terminal dimerization domain. However, it lacks the C-terminal SH3-like domain of DtxR/IdeR. The metal ion binding site of MntR is located at the interface of the two domains, whereas the DtxR/IdeR subunit contains two metal ion binding sites, the primary and ancillary sites, separated by 9 Å. In this paper, we reported the crystal structures of the apo and Mn²⁺-bound forms of MntR from Bacillus halodurans, and analyze the structural basis of the metal ion binding site. The crystal structure of the Mn²⁺-bound form is almost identical to the apo form of MntR. In the Mn²⁺-bound structure, one subunit contains a binuclear cluster of manganese ions, the A and C sites, but the other subunit forms a mononuclear complex. Structural data about MntR from B. halodurans supports the previous hypothesizes about manganese-specific activation mechanism of MntR homologues.

Bioleaching of electronic waste using bacteria isolated from the marine sponge Hymeniacidon heliophila (Porifera)

The bacteria isolated from Hymeniacidon heliophila sponge cells showed bioleaching activity. The most active strain, Hyhel-1, identified as Bacillus sp., was selected for bioleaching tests under two different temperatures, 30°C and 40°C, showing rod-shaped cells and filamentous growth, respectively. At 30°C, the bacteria secreted substances which linked to the leached copper, and at 40°C metallic nanoparticles were produced inside the cells. In addition, infrared analysis detected COOH groups and linear peptides in the tested bacteria at both temperatures. The Hyhel-1 strain in presence of electronic waste (e-waste) induced the formation of crust, which could be observed due to bacteria growing on the e-waste fragment. SEM-EDS measurements showed that the bacterial net surface was composed mostly of iron (16.1% w/w), while a higher concentration of copper was observed in the supernatant (1.7% w/w) and in the precipitated (49.8% w/w). The substances linked to copper in the supernatant were sequenced by MALDI-TOF-ms/ms and identified as macrocyclic surfactin-like peptides, similar to the basic sequence of Iturin, a lipopeptide from Bacillus subtilis. Finally, the results showed that Hyhel-1 is a bioleaching bacteria and cooper nanoparticles producer and that this bacteria could be used as a copper recovery tool from electronic waste.

Biosorption of Pb(II) by Bacillus badius AK strain originating from rotary drum compost of water hyacinth

The presence of heavy metals in the environment due to industrial activities is of serious concern because of their toxic behaviour towards humans and other forms of life. Biosorption of Pb(II) using dry bacterial biomass of Bacillus badius AK, previously isolated from water hyacinth compost, has been undertaken in batch system. The optimum conditions of biosorption were determined by investigating the initial pH, contact time, initial biomass dosage at constant temperature of 40 °C, initial metal concentration of 100 mg/L and rotational speed of 150 rpm. The optimum pH was found to be 5 and equilibrium contact time was 2.5 h. The maximum biosorption capacity of Pb(II) on Bacillus badius AK was 138.8 mg/g at an initial concentration of 100 mg/L. A kinetics study revealed that the adsorption process followed pseudo second order rate kinetics. The experimental data were fitted to the Langmuir isotherm. Characterization of the biomass indicated the presence of several functional groups. The results indicated that the bacterium Bacillus badius AK is efficient for the removal of Pb(II).

Arsenic mediated modifications in Bacillus aryabhattai and their biotechnological applications for arsenic bioremediation

The present study reports the arsenic (As) tolerance mechanism of bacteria Bacillus aryabhattai (NBRI014). The data explores the intracellular accumulation and volatilization of As from the culture medium after 48 h of exposure to 25,000 mg l^-1 arsenate As(V). The study also provides the evidence of presence of ars operon in bacteria, which may have played an important role in reducing As toxicity. Additionally, we found 7 differentially expressed proteins to be up-regulated in bacterial cells upon As exposure which may have role in reducing As toxicity inside bacterial cells. Furthermore, Fourier transform infrared (FTIR) spectroscopic techniques were useful to describe the structural and compositional alterations in bacterial cells after As treatment. It showed the changes in peak positions of the spectrum pattern when NBRI014 was grown in medium containing As, indicating that these functional groups viz. (amino, alkyl halides and hydroxyl) present on bacterial surface, which may be involved in As binding. The above results signify that biotechnological application of the isolate NBRI014 could be helpful in removal of As from polluted sites.

Antibacterial metabolites and bacteriolytic enzymes produced by Bacillus pumilus during bacteriolysis of Arthrobacter citreus

The marine isolate Bacillus pumilus SBUG 1800 is able to lyse living cells of Arthrobacter citreus on solid media as well as pasteurized A. citreus cells in liquid mineral salt medium. The cultivation of B. pumilus in the presence of pasteurized A. citreus is accompanied by an enhanced production of 2,5-diketopiperazines (DKPs). DKPs inhibit bacterial growth, but do not seem to cause bacteriolysis. This study shows that B. pumilus also lyses living cells of A. citreus in co-culture experiments as an intraguild predator, even if the inoculum of B. pumilus is low. In order to characterize the bacteriolytic process, more precisely changes in the extracellular metabolome and proteome have been analyzed under different culture conditions. Besides the known DKPs, a number of different pumilacidins and bacteriolytic enzymes are produced. Two lipopeptides with [M + H](+) = 1008 and [M + H](+) = 1022 were detected and are proposed to be pumilacidin H and I. While the lipopeptides lyse living bacterial cells in lysis test assays, a set of extracellular enzymes degrades the dead cell material. Two of the cell wall hydrolases involved have been identified as N-acetylmuramoyl-L-alanine amidase and beta-N-acetylglucosaminidase. These findings together with electron microscopic and cell growth monitoring during co-culture experiments give a detailed view on the bacteriolytic process.

Assessing the Sporicidal Activity of Oligo-p-phenylene Ethynylenes and Their Role as Bacillus Germinants

A wide range of oligo-p-phenylene ethynylenes has been shown to exhibit good biocidal activity against both Gram-negative and Gram-positive bacteria. While cell death may occur in the dark, these biocidal compounds are far more effective in the light as a result of their ability to sensitize the production of cell-damaging reactive oxygen species. In these studies, the interactions of a specific cationic oligo-p-phenylene ethynylene with spore-forming Bacillus atrophaeus and Bacillus anthracis Sterne have been investigated. Flow cytometry assays are used to rapidly monitor cell death as well as spore germination. This compound effectively killed Bacillus anthracis Sterne vegetative cells (over 4 log reduction), presumably by severe perturbations of the bacterial cell wall and cytoplasmic membrane, while also acting as an effective spore germinant in the dark. While 2 log reduction of B. anthracis Sterne spores was observed, it is hypothesized that further killing could be achieved through enhanced germination.

A bacterial spore model of pulsed electric fields on spore morphology change revealed by simulation and SEM

A two-layered spore model was proposed to analyze morphological change of bacterial spores subjected under pulsed electric fields. The outer layer, i.e. spore coat, was defined by Mooney-Rivlin hyper-elastic material model. The inner layer, i.e. peptidoglycan and spore core, was modeled by applying additional adhesion forces. The effect of pulsed electric fields on surface displacement was simulated in COMSOL Multiphysics and verified by SEM. The electro-mechanical theory, considering spore coat as a capacitor, was used to explain concavity; and the thin viscoelastic film theory, considering membrane bilayer as fluctuating surfaces, was used to explain leakage forming. Mutual interaction of external electric fields, charged spores, adhesion forces and ions movement were all predicted to contribute to concavity and leakage.

Inactivation and ultrastructure analysis of Bacillus spp. and Clostridium perfringens spores

Bacterial endospores are resistant to many environmental factors from temperature extremes to ultraviolet irradiation and are generally more difficult to inactivate or kill than vegetative bacterial cells. It is often considered necessary to treat spores or samples containing spores with chemical fixative solutions for prolonged periods of time (e.g., 1-21 days) to achieve fixation/inactivation to enable electron microscopy (EM) examination outside of containment laboratories. Prolonged exposure to chemical fixatives, however, can alter the ultrastructure of spores for EM analyses. This study was undertaken to determine the minimum amount of time required to inactivate/sterilize and fix spore preparations from several bacterial species using a universal fixative solution for EM that maintains the ultrastructural integrity of the spores. We show that a solution of 4% paraformaldehyde with 1% glutaraldehyde inactivated spore preparations of Bacillus anthracis, Bacillus cereus, Bacillus megaterium, Bacillus thuringiensis, and Clostridium perfringens in 30 min, and Bacillus subtilis in 240 min. These results suggest that this fixative solution can be used to inactivate and fix spores from several major groups of bacterial spore formers after 240 min, enabling the fixed preparations to be removed from biocontainment and safely analyzed by EM outside of biocontainment.

[Electron microscopy of the surfaces of bacillary spores]

The surface structures of the spores of Bacillus. cereus, B. thuringiensis, and Brevibacillus laterosporus were studied by transmission and scanning electron microscopy. Platinum deposition and negative staining with uranyl acetate revealed appendages and exosporium in B. thuringiensis and B. cereus. The exosporium structure was visualized by negative staining and ultrathin sectioning. For staining the exosporium polysaccharide, Alcian blue was used during fixation. The results obtained show the differences in structural organization of appendages and exosporium in different strains. Canoe-shaped inclusions were revealed in all Br. laterosporus strains, while strain IGM16-92 had a fibrillar capsule as well. Electron microscopy using a dual beam scanning electron microscope Quanta 200 3D provided the information of the spore surface relief without sample treatment (fixation and dehydration). The spores of Br. laterosporus strains had folded surface, unlike the smooth surface of B. cereus and B. thuringiensis spores. Diversity of external spore structures was shown within a species, which may be used for detection of bacteria at the strain level. Optimized procedures for visualization of spore surface by different electron microscopic techniques were discussed.

Polymeric macroporous formulations for the control release of mosquitocidal Bacillus sphaericus ISPC-8

Bio-polymeric mosquitocidal formulations were developed for the control release of Bacillus sphaericus ISPC-8 by the immobilization of its spore-crystal complex onto the macroporous polymeric matrices. The biodegradable formulations were synthesized at sub-zero temperature using natural polymeric substrates like agarose, alginate, cellulose, non-adsorbent cotton, wooden cork powder and also magnetite nanoparticles. The obtained polymeric matrices were morphologically characterized, which showed 85-90% porosity, uniform pores distribution, high permeability and controlled degradation (19-30%) in 4 weeks depending upon the composition of formulations. Further, the polymeric macroporous formulations were tested for persistence of mosquitocidal activity against Culex quinquefasciatus larvae. Unformulated B. sphaericus ISPC-8 spores retained 54% of larvicidal activity after 7 days, which completely reduced after 35 days of treatment. However, the immobilized B. sphaericus spores in agarose-alginate formulations showed high larvicidal activity on day 7 and retained about 45% activity even after 35 days of treatments. Studies on UV-B and pH dependent inactivation of toxins and spore viability showed that these formulations were significantly protecting the spores as compared to the unformulated spores, which suggest its potential application for the mosquito control program.

Polyester production by halophilic and halotolerant bacterial strains obtained from mangrove soil samples located in Northern Vietnam

This research article reports halophilic and halotolerant bacteria isolated from mangrove forests located in Northern Vietnam. Several of these bacteria were able to synthesize polyhydroxyalkanoates (PHAs). PHAs are polyesters stored by microorganisms under the presence of considerable amounts of a carbon source and deficiency of other essential nutrient such as nitrogen or phosphorous. Mangrove forests in Northern Vietnam are saline coastal habitats that have not been microbiologically studied. Mangrove ecosystems are, in general, rich in organic matter, but deficient in nutrients such as nitrogen and phosphorus. We have found about 100 microorganisms that have adapted to mangrove forests by accumulating PHAs. The production of polyesters might therefore be an integral part of the carbon cycle in mangrove forests. Three of the strains (ND153, ND97, and QN194) isolated from the Vietnamese forests were identified as Bacillus species, while other five strains (QN187, ND199, ND218, ND240, and QN271) were phylogenetically close related to the α-proteobacterium Yangia pacifica. These strains were found to accumulate PHAs in noticeable amounts. Polymer inclusions and chemical structure were studied by transmission electron microscopy and proton nuclear magnetic resonance (NMR) spectroscopy analyses, respectively. Strains ND153, ND97, QN194, QN187, ND240, and QN271 synthesized poly(3-hydroxybutyrate) (PHB) from glucose, whereas strains ND199 and ND218 synthesized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) from this carbohydrate. With the exception of strain QN194, the strains accumulated PHBV when a combination of glucose and propionate was included in the culture medium. The polymer yields and cell growth reached by one Bacillus isolate, strain ND153, and one Gram-negative bacterium, strain QN271, were high and worth to be researched further. For experiments performed in shake flasks, strain ND153 reached a maximum PHBV yield of 71 wt% and a cell dry weight (CDW) of 3.6 g/L while strain QN271 attained a maximum PHB yield of 48 wt% and a CDW of 5.1 g/L. Both strain ND153 and strain QN271 may only represent a case in point that exemplifies of the potential that mangrove forests possess for the discovery of novel halophilic and halotolerant microorganisms able to synthesize different types of biopolyesters.

Calcium carbonate mineralization: involvement of extracellular polymeric materials isolated from calcifying bacteria

This study highlights the role of specific outer bacterial structures, such as the glycocalix, in calcium carbonate crystallization in vitro. We describe the formation of calcite crystals by extracellular polymeric materials, such as exopolysaccharides (EPS) and capsular polysaccharides (CPS) isolated from Bacillus firmus and Nocardia calcarea. Organic matrices were isolated from calcifying bacteria grown on synthetic medium--in the presence or absence of calcium ions--and their effect on calcite precipitation was assessed. Scanning electron microscopy observations and energy dispersive X-ray spectrometry analysis showed that CPS and EPS fractions were involved in calcium carbonate precipitation, not only serving as nucleation sites but also through a direct role in crystal formation. The utilization of different synthetic media, with and without addition of calcium ions, influenced the biofilm production and protein profile of extracellular polymeric materials. Proteins of CPS fractions with a molecular mass between 25 and 70 kDa were overexpressed when calcium ions were present in the medium. This higher level of protein synthesis could be related to the active process of bioprecipitation.

[Thermotolerance of Bacillus licheniformis CGMCC 3963 from high-temperature Daqu]

OBJECTIVE

The use of high-temperature Daqu is an important characteristic in Chinese Maotai-flavor liquor making. Thermostable bacteria are predominant in high-temperature Daqu. They play important roles in Maotai-flavor liquor making. Learning the mechanism of thermotolerant performance of bacteria would provide insight into characteristics of this liquor making.

METHODS

We determined the thermotolerance of Bacillus licheniformis CGMCC 3963, and analyzed cell morphology, genomics and transcriptomics.

RESULTS

B. licheniformis CGMCC 3963 could survive at 55 degrees C and produce many capsules. Genes of class I heat-shock proteins and polyglutamate biosynthesis were both up-regulated.

CONCLUSION

Much heat-shock proteins and capsule polyglutamate maintained the survival of cell with heat stress.

Characterization of two metal resistant Bacillus strains isolated from slag disposal site at Burnpur, India

Two strains of Bacillus sp. resistant to arsenate and lead designated as AsSP9 and PbSP6, respectively were isolated from the slag disposal site. They were identified to be related to Bacillus cereus cluster on the basis of 16S rDNA based sequence analysis and phenotypic characteristics. Both were rod-shaped (AsSP9, 2-5 microm and PbSP6, 2-4 microm), aerobic, salt tolerant (2-8% NaCI), endospore forming bacteria with minor differences like the AsSP9 showed sporangial bulging and PbSP6 had positive lipase activity. The temperature range for their growth was 20-40 degrees C and pH range 6.0-9.0 with an optimum temperature of 37 degrees C and pH of 7 for both strains. The principal nitrogen sources forAsSP9 and PbSP6 were DL-Tryptophan and L-Phenylalanine, respectively. The suitable carbon source forAsSP9 was lactose and for PbSP6 sucrose. The heavy metal accumulation efficiency was found to be 0.0047 mg g(-1) of dry mass forAsSP9 and 0.686 mg g(-1) of dry mass for PbSP6.

Rhamnolipid mediated disruption of marine Bacillus pumilus biofilms

Removal of detrimental biofilms from surfaces exposed in the marine environment remains a challenge. A strain of Bacillus pumilus was isolated from the surface of titanium coupons immersed in seawater in the vicinity of Madras Atomic Power Station (MAPS) on the East coast of India. The bacterium formed extensive biofilms when compared to species such as Bacillus licheniformis, Pseudomonas aeruginosa PAO1 and Pseudomonas aureofaciens. A commercially available rhamnolipid was assessed for its ability to inhibit adhesion and disrupt pre-formed B. pumilus biofilms. The planktonic growth of B. pumilus cells was inhibited by concentrations >1.6mM. We studied the effect of various concentrations (0.05-100mM) of the rhamnolipid on adhesion of B. pumilus cells to polystyrene microtitre plates, wherein the effectiveness varied from 46 to 99%. Biofilms of B. pumilus were dislodged efficiently at sub-MIC concentrations, suggesting the role of surfactant activity in removing pre-formed biofilms. Scanning electron microscopy (SEM) confirmed the removal of biofilm-matrix components and disruption of biofilms by treatment with the rhamnolipid. The results suggest the possible use of rhamnolipids as efficient anti-adhesive and biofilm-disrupting agents with potential applications in controlling biofilms on surfaces.

Constructing fluorogenic Bacillus spores (F-spores) via hydrophobic decoration of coat proteins

Background

Bacterial spores are protected by a coat consisting of about 60 different proteins assembled as a biochemically complex structure with intriguing morphological and mechanical properties. Historically, the coat has been considered a static structure providing rigidity and mainly acting as a sieve to exclude exogenous large toxic molecules, such as lytic enzymes. Over recent years, however, new information about the coat's architecture and function have emerged from experiments using innovative tools such as automated scanning microscopy, and high resolution atomic force microscopy.

Principal Findings

Using thin-section electron microscopy, we found that the coat of Bacillus spores has topologically specific proteins forming a layer that is identifiable because it spontaneously becomes decorated with hydrophobic fluorogenic probes from the milieu. Moreover, spores with decorated coat proteins (termed F-spores) have the unexpected attribute of responding to external germination signals by generating intense fluorescence. Fluorescence data from diverse experimental designs, including F-spores constructed from five different Bacilli species, indicated that the fluorogenic ability of F-spores is under control of a putative germination-dependent mechanism.

Conclusions

This work uncovers a novel attribute of spore-coat proteins that we exploited to decorate a specific layer imparting germination-dependent fluorogenicity to F-spores. We expect that F-spores will provide a model system to gain new insights into structure/function dynamics of spore-coat proteins.

[Colonization of cucumber rhizosphere by phosphate-mobilizing bacteria of Bacillus genus]

An ability of phosphate-mobilizing bacteria, related to four species of Bacillus genus, to colonize the cucumber root zone has been investigated. It has been found that all the studied strains can adapt to the root zone of those plants colonizing its parts to different extent. Essential nonuniformity of the root surface populating with bacteria is noted. Microcolonies of these organisms are formed in some root zones. This peculiarity is probably caused both by the difference in the number and composition of exudates of some zones of the plant roots, and by peculiarities of trophic requirements of the strains of studied bacteria The paper is presented in Ukrainian.

Biological synthesis of gold nanocubes from Bacillus licheniformis

Microorganisms play an important role in the eco-friendly synthesis of metal nanoparticles. This study illustrates the synthesis of gold nanocubes using the bacterium Bacillus licheniformis after 48 h of incubation at room temperature. The morphology of the samples was analyzed using scanning electron microscopy (SEM) and the particles formed were characterized to be nanocubes. The size of gold nanocubes in aqueous solution has been calculated using UV-Vis spectroscopy, XRD and SEM measurements. The nanoparticles are found to be polydisperse nanocubes in the size range 10-100 nm.

Antagonism of Bacillus spp. isolated from marine biofilms against terrestrial phytopathogenic fungi

We aimed at determining the antagonistic behavior of bacteria derived from marine biofilms against terrestrial phytopathogenic fungi. Some bacteria closely related to Bacillus mojavensis (three isolates) and Bacillus firmus (one isolate) displayed antagonistic activity against Colletotrichum gloeosporioides ATCC 42374, selected as first screen organism. The four isolates were further quantitatively tested against C. gloeosporioides, Colletotrichum fragariae, and Fusarium oxysporum on two culture media, potato dextrose agar (PDA) and a marine medium-based agar [yeast extract agar (YEA)] at different times of growth of the antagonists (early, co-inoculation with the pathogen and late). Overall antagonistic assays showed differential susceptibility among the pathogens as a function of the type of culture media and time of colonization (P < 0.05). In general, higher suppressive activities were recorded for assays performed on YEA than on PDA; and also when the antagonists were allowed to grow 24 h earlier than the pathogen. F. oxysporum was the most resistant fungus while the most sensitive was C. gloeosporioides ATCC 42374. Significant differences in antagonistic activity (P < 0.05) were found between the different isolates. In general, Bacillus sp. MC3B-22 displayed a greater antagonistic effect than the commercial biocontrol strain Bacillus subtilis G03 (Kodiak). Further incubation studies and scanning electronic microscopy revealed that Bacillus sp. MC3B-22 was able to colonize, multiply, and inhibit C. gloeosporioides ATCC 42374 when tested in a mango leaf assay, showing its potential for fungal biocontrol. Additional studies are required to definitively identify the active isolates and to determine their mode of antifungal action, safety, and biocompatibility.

Bacteria-based controlled assembly of metal chalcogenide hollow nanostructures with enhanced light-harvesting and photocatalytic properties

Herein, a general bottom-up approach is proposed for the controlled assembly of metal chalcogenide nanoparticles into biomorphic porous hollow nanostructures by a sonochemical method using bacteria as morph-biotemplates. Biomorphic PbS and ZnS hollow nanostructures have been successfully synthesized with two species of bacteria cocci and bacillus as morph-templates. The biomorphic hollow assemblies possess shape-controllable, size-tunable and shell-thickness-adjustable characteristics. Thus, the structure and morphology of the hollow assemblies may be varied in a controllable way to tailor their properties over a broad range. A preliminary study on the light-harvesting properties of PbS and ZnS hollow spheres revealed that the hollow and porous structure is clearly far more favorable for the absorption of light than solid counterparts, which accounts for both multiple scattering effects at the large voids (hollow cavities) and Rayleigh scattering by nanovoids of the exterior shells. Furthermore, photocatalytic studies of ZnS nanostructures by degradation of acid fuchsine under solar irradiation have proved that the hollow structures possess superior photocatalytic activity to the corresponding solid counterparts. This versatile approach provides an effective route for the further extensive study of the distinct properties imparted by hollow nanostructures and extends their application potentials in photocatalysis and solar energy storage/conversion.

Bacillus pallidus sp. nov., isolated from forest soil

A Gram-positive bacterium, designated strain CW 7(T), was isolated from forest soil in Anhui Province, south-east China. Cells were strictly aerobic, motile with peritrichous flagella and rod-shaped. The strain grew optimally at 30-37 degrees C and pH 7.0-8.0. The major fatty acids of strain CW 7(T) were anteiso-C(15 : 0), iso-C(15 : 0) and anteiso-C(17 : 0). The predominant menaquinone was MK-7. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The G+C content of the genomic DNA was 42.3 mol%. Phylogenetic analysis indicated that strain CW 7(T) belonged to a monophyletic cluster within the genus Bacillus and showed 16S rRNA gene sequence similarities of less than 96.5 % to recognized species of the genus Bacillus. The results of the polyphasic taxonomic study, including phenotypic, chemotaxonomic and phylogenetic analyses, showed that strain CW 7(T) represents a novel species of the genus Bacillus, for which the name Bacillus pallidus sp. nov. is proposed. The type strain is CW 7(T) (=KCTC 13200(T)=CCTCC AB 207188(T)=LMG 24451(T)).

Isolation and identification of an alkaliphilic Bacillus flexus XJU-3 and analysis of its alkaline amylase

OBJECTIVE

To isolate and identify a new Bacillus strain capable of growing under highly alkaline conditions as alkaline amylase producers and to characterize its enzymatic properties.

METHODS

The isolates were sampled from alkaline sewage in Shihezi city, Xinjiang and screened by plating them on the amylase agar medium depending on the halo zone diameter. The alkaline amylase producer with best enzymatic activity was designated as XJU-3. XJU-3 was identified by its physiological and biochemical characteristics, 16S rDNA sequence homology, and the content of its major cellular fatty acids.

RESULTS

XJU-3 was a Gram-positive, spore-forming, aerobic, motile rod alkaliphilic bacterium. It can grow at a broad range of pH (4.0-12.5) in Luria broth medium and its optimum growth was at pH 10 and 37 degrees C. Its NaCl tolerance was up to 15%. Its major cellular fatty acids were anteiso-C15:0 and iso-C15:0. Comparative 16S rRNA gene sequence analyses showed that XJU-3 was most closely related to Bacillus flexus, with 99% similarity. The genomic DNA (G+C) content of our isolate was 39.13 mol %. XJU-3 produced extracellular alkaline amylase, and its maximal enzyme activity was observed at 40 degrees C and pH 10.0. More than 70% of the enzymatic activity was remained at pH 13.0. The enzyme activity was strongly enhanced with the presence of Co2+ and Mg2+.

CONCLUSION

The strain XJU-3 was confirmed as B. flexus. Owing to its excellent pH tolerance, the kinds of major cellular fatty acids, and several phenotypic characteristics that were different from the description of the reference strain, the strain was further classified as a new variant of the species B. flexus. The enzymatic properties of XJU-3 alkaline amylase indicated its potential in industrial applications.

Electron holography of biological samples

In this paper, we summarise the development of off-axis electron holography on biological samples starting in 1986 with the first results on ferritin from the group of Tonomura. In the middle of the 1990s strong interest was evoked, but then stagnation took place because the results obtained at that stage did not reach the contrast and the resolution achieved by conventional electron microscopy. To date, there exist only a few ( approximately 12) publications on electron holography of biological objects, thus this topic is quite small and concise. The reason for this could be that holography is mostly established in materials science by physicists. Therefore, applications for off-axis holography were powerfully pushed forward in the area of imaging, e.g. electric or magnetic micro- and nanofields. Unstained biological systems investigated by means of off-axis electron holography up to now are ferritin, tobacco mosaic virus, a bacterial flagellum, T5 bacteriophage virus, hexagonal packed intermediate layer of bacteria and the Semliki Forest virus. New results of the authors on collagen fibres and surface layer of bacteria, the so-called S-layer 2D crystal lattice are presented in this review. For the sake of completeness, we will shortly discuss in-line holography of biological samples and off-axis holography of materials related to biological systems, such as biomaterial composites or magnetotactic bacteria.

Exopolysaccharide production by Bacillus strains colonizing packaging foils

The influence of the chemical composition of medium, availability of glucose and pH on the production of exopolysaccharides (EPS) by different Bacillus strains were investigated. Bacillus strains were isolated from the surface of polyethylene foils modified with mineral compounds after their biodegradation in compost soil. Moreover, the effect ofEPS production on bacterial adhesion onto the surface of the materials was examined. The enhanced synthesis of exopolysaccharides in nutrient-starved conditions was revealed. The most effective synthesis of polymers was observed during the logarithmic phase of culture growth. The increased amount of EPS facilitated bacterial adhesion to material surfaces. It was determined that the biofilm on the material surface positively affects its biodegradation. Based on the results, we conclude that the biodegradation of polymers may be accelerated in low-nutrient environment.

Surface appendages of bacterial spores

Bacilli and Clostridia generate dormant, highly resistant cells, called spores, in response to stress. Spores of many species are decorated by morphologically diverse structures of unknown function called appendages that have yet to be studied at the molecular level. In this issue, Walker et al. employ reverse genetics to identify genes encoding protein components of the ornate ribbon-like appendages of the spores of Clostridium taeniosporum. Their results reveal striking commonalities between these genes and those encoding outer structures in phylogenetically and taxonomically distinct spore-forming species. The insights gained from this work demonstrate the value of analysis of non-model spore formers.

Production of tannase by the immobilized cells of Bacillus licheniformis KBR6 in Ca-alginate beads

AIMS

The present study was aimed at finding the optimal conditions for immobilization of Bacillus licheniformis KBR6 cells in calcium-alginate (Ca-alginate) beads and determining the operational stability during the production of tannin-acyl-hydrolase (tannase) under semicontinous cultivation.

METHODS AND RESULTS

The active cells of B. licheniformis KBR6 were immobilized in Ca-alginate and used for the production of tannase. The influence of alginate concentration (5, 10, 20 and 30 g l(-1)) and initial cell loading on enzyme production were studied. The production of tannase increased significantly with increasing alginate concentration and reached a maximum enzyme yield of 0.56 +/- 0.03 U ml(-1) at 20 g l(-1). This was about 1.70-fold higher than that obtained by free cells. The immobilized cells produced tannase consistently over 13 repeated cycles and reached a maximum level at the third cycle. Scanning electron microscope study indicated that the cells in Ca-alginate beads remain in normal shape.

CONCLUSIONS

The Ca-alginate entrapment is a promising immobilization method of B. licheniformis KBR6 for repeated tannase production. Tannase production by immobilized cells is superior to that of free cells because it leads to higher volumetric activities within the same period of fermentation.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report of tannase production from immobilized bacterial cells. The bacterium under study can produce higher amounts of tannase with respect to other fungal strains within a short cultivation period.

Rapid diagnostic thin section electron microscopy of bacterial endospores

Emerging infectious diseases such as SARS and the bioterror attacks with anthrax spores that occurred after September 11th, 2001 have highlighted the need to be better prepared for the detection and management of infectious pathogens that threaten public health. Negative staining electron microscopy is one method used to screen environmental and clinical samples for relevant infectious pathogens. Unfortunately, bacterial endospores, like those of Bacillus anthracis, are difficult to identify using this method because of their density that prevents imaging of structural details. Thin section electron microscopy would be an alternative method but this usually requires a few days for preparation and diagnosis. In the present paper we describe the development of a rapid thin section protocol, using mainly Bacillus subtilis spores as a model, which allows an unequivocal diagnosis of endospores within 2 h. The protocol involves chemical fixation assisted by heat or microwaves, rapid dehydration, embedding in the low-viscosity resin LR White and chemically enhanced polymerization. Structural preservation of spores is comparable to preservation after standard Epon embedding. Immunolabeling experiments using B. atrophaeus spores and a specific antibody suggest that the protocol preserves significant antigenicity for on-section immunocytochemistry and therefore offers the possibility for the strain typing of spores using specific antibodies. Further experiments with vegetative bacteria, viruses and cell cultures indicate that the rapid thin section protocol not only preserves spores but also other biological structures. Because of its universality and speed the described protocol complements negative staining electron microscopy as a front line method for the morphology-based diagnosis of pathogens in environmental and clinical samples.

Bacterially induced mineralization of calcium carbonate: the role of exopolysaccharides and capsular polysaccharides

Bacterially induced carbonate mineralization has been proposed as a new method for the restoration of limestones in historic buildings and monuments. We describe here the formation of calcite crystals by extracellular polymeric substances isolated from Bacillus firmus and Bacillus sphaericus. We isolated bacterial outer structures (glycocalix and parietal polymers), such as exopolysaccharides (EPS) and capsular polysaccharides (CPS) and checked for their influence on calcite precipitation. CPS and EPS extracted from both B. firmus and B. sphaericus were able to mediate CaCO3 precipitation in vitro. X-ray microanalysis showed that in all cases the formed crystals were calcite. Scanning electron microscopy showed that the shape of the crystals depended on the fractions utilized. These results suggest the possibility that biochemical composition of CPS or EPS influences the resulting morphology of CaCO3. There were no precipitates in the blank samples. CPS and EPS comprised of proteins and glycoproteins. Positive alcian blue staining also reveals acidic polysaccharides in CPS and EPS fractions. Proteins with molecular masses of 25-40 kDa and 70 kDa in the CPS fraction were highly expressed in the presence of calcium oxalate. This high level of synthesis could be related to the binding of calcium ions and carbonate deposition.

Feasibility of detection and identification of individual bioaerosols using laser-induced breakdown spectroscopy

The detection and identification of individual bioaerosols using laser-induced breakdown spectroscopy (LIBS) is investigated using aerosolized Bacillus spores. Spores of Bacillus atrophaeous, Bacillus pumilus, and Bacillus stearothemophilus were introduced into an aerosol flow stream in a prescribed manner such that single-particle LIBS detection was realized. Bacillus spores were successfully detected based on the presence of the 393.4- and 396.9-nm calcium atomic emission lines. Statistical analyses based on the aerosol number density, the LIBS-based spore sampling frequency, and the distribution of the resulting calcium mass loadings support the conclusion of individual spore detection within single-shot laser-induced plasmas. The average mass loadings were in the range of 2-3 fg of calcium/Bacillus spore, which corresponds to a calcium mass percentage of approximately 0.5%. While individual spores were detected based on calcium emission, the resulting Bacillus spectra were free from CN emission bands, which has implications for the detection of elemental carbon, and LIBS-based detection of single spores based on the presence of magnesium or sodium atomic emission was unsuccessful. Based on the current instrumental setup and analyses, real-time LIBS-based detection and identification of single Bacillus spores in ambient (i.e., real life) conditions appears unfeasible.

Extracellular polymeric bacterial coverages as minimal area surfaces

Surfaces formed by extracellular polymeric substances enclosing individual and some small communities of Acidithiobacillus ferrooxidans on plates of hydrophobic silicon and hydrophilic mica are analyzed by means of atomic force microscopy imaging. Accurate nanoscale descriptions of such coverage surfaces are obtained. The good agreement with the predictions of a rather simple but realistic theoretical model allows us to conclude that they correspond, indeed, to minimal area (constant mean curvature) surfaces enclosing a given volume associated with the encased bacteria. This is, to the best of our knowledge, the first shape characterization of the coverage formed by these biomolecules, with potential applications to the study of biofilms.

A novel highly boron tolerant bacterium, Bacillus boroniphilus sp. nov., isolated from soil, that requires boron for its growth

Three strains of gram-positive, motile, rod-shaped and boron (B)-tolerant bacterium were isolated from naturally B containing soil of Hisarcik area in the Kutahya Province, Turkey. The strains, designated as T-14A, T-15Z(T) and T-17s, produced spherical or ellipsoidal endospores in a terminal bulging sporangium. The strains required B for the growth and can tolerate more than 450 mM B. These also tolerated up to 7.0% (w/v) NaCl in the presence of 50 mM B in agar medium but grew optimally without NaCl. The temperature range for growth was 16-37 degrees C (optimal of 30 degrees C), whereas the pH range was 6.5-9.0 (optimal of 7.5-8.5). The DNA G + C content was 41.1-42.2 mol% and the predominant cellular fatty acid was iso-C(15:0). The major respiratory quinone system was detected as MK-7 and the diamino acid of the peptidoglycan was meso-diaminopimelic acid. Based on phenotypic and chemotaxonomic characteristics, phylogenetic analysis of 16S rRNA gene sequences data and DNA-DNA re-association values, we concluded that the three strains belong to a novel species of the genus Bacillus, the type strain of which is T-15Z(T) and for which we proposed the name, B. boroniphilus sp. nov. (DSM 17376(T) = IAM 15287(T) = ATCC BAA-1204(T)).

An alternative bactericidal mechanism of action for lantibiotic peptides that target lipid II

Lantibiotics are polycyclic peptides containing unusual amino acids, which have binding specificity for bacterial cells, targeting the bacterial cell wall component lipid II to form pores and thereby lyse the cells. Yet several members of these lipid II-targeted lantibiotics are too short to be able to span the lipid bilayer and cannot form pores, but somehow they maintain their antibacterial efficacy. We describe an alternative mechanism by which members of the lantibiotic family kill Gram-positive bacteria by removing lipid II from the cell division site (or septum) and thus block cell wall synthesis.

Bacillus sporothermodurans and other highly heat-resistant spore formers in milk

A recent example of a micro-organism causing undesired growth in consumer milk is Bacillus sporothermodurans producing highly heat-resistant spores (HRS) which may survive ultra-high temperature (UHT) treatment or industrial sterilization. Molecular typing showed a heterogeneous group of farm isolates (non-HRS strains), but a clonal group of UHT isolates from diverse European countries and other continents (HRS-clone) suggesting a common source. During a survey of Belgian dairy farms for the presence of potentially highly heat-resistant spore formers, high numbers of these spores were detected in filter cloth, green crop and fodder samples. The strain collection showed a high taxonomic diversity with 18 potentially new species and with Bacillus licheniformis and Geobacillus pallidus as predominating species overall. Seventeen B. sporothermodurans isolates were identified, mainly originating from feed concentrate. Heat resistance studies showed the UHT resistance of B. sporothermodurans spores present in industrially contaminated UHT milk, but a lower heat resistance of laboratory-grown strains (HRS and non-HRS). Hydrogen peroxide, used as sanitizer in the dairy industry, was found to induce higher heat resistance of laboratory-grown B. sporothermodurans strains to a certain level. This indicates that sublethal stress conditions may affect the heat resistance. By transmission electron microscopy, structural differences at the spore level were found between HRS and non-HRS strains. The data indicate that the attainment of extreme heat resistance is rather multifactorial.

Biodegradation of benzo[a]pyrene in soil by Mucor sp. SF06 and Bacillus sp. SB02 co-immobilized on vermiculite

Two indigenous microorganisms, Bacillus sp. SB02 and Mucor sp. SF06, capable of degrading polycyclic aromatic hydrocarbons (PAHs) were co-immobilized on vermiculite by physical adsorption and used to degrade benzo[a] pyrene (BaP). The characteristics of BaP degradation by both free and co-immobilized microorganism were then investigated and compared. The removal rate using the immobilized bacterial-fungal mixed consortium was higher than that of the freely mobile mixed consortium. 95.3% of BaP was degraded using the co-immobilized system within 42 d, which was remarkably higher than the removal rate of that by the free strains. The optimal amount of inoculated co-immobilized system for BaP degradation was 2%. The immobilized bacterial-fungal mixed consortium also showed better water stability than the free strains. Kinetics of BaP biodegradation by co-immobilized SF06 and SB02 were also studied. The results demonstrated that BaP degradation could be well described by a zero-order reaction rate equation when the initial BaP concentration was in the range of 10-200 mg/kg. The scanning electronic microscope (SEM) analysis showed that the co-immobilized microstructure was suitable for the growth of SF06 and SB02. The mass transmission process of co-immobilized system in soil is discussed. The results demonstrate the potential for employing the bacterial-fungal mixed consortium, co-immobilized on vermiculite, for in situ bioremediation of BaP.

[Study on identification, colonization and reorganization of rice endophytic bacteria]

Endophytic SR-15, SR-25 and SL-37 strains screened from rice hybrid D you 527 in Sichuan were analyzed. Through penetration and microscopic test, the strains were found be mainly located in the cell gap, vacuole and cytoplasm. PUC18 transferring and ERIC-PCR showed that the recombination strain SR-15 could grow in the plant stably. The strain was identified as Bacillus halmapalus based on its chemical components of cell wall, physiological and biochemical characters. It was also shown that the strain was not injurious to rice plant, instead, it promoted rice plant growth by penetration. The Cry1Ac gene was transferred into the stain and verified by Southern analysis. Cry1Ac-transferred SR-15 was toxic to the Chilo suppressalis, brought about death ratio as high as 84.2%.

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 atrophaeus outer spore coat assembly and ultrastructure

Our previous atomic force microscopy (AFM) studies successfully visualized native Bacillus atrophaeus spore coat ultrastructure and surface morphology. We have shown that the outer spore coat surface is formed by a crystalline array of approximately 11 nm thick rodlets, having a periodicity of approximately 8 nm. We present here further AFM ultrastructural investigations of air-dried and fully hydrated spore surface architecture. In the rodlet layer planar and point defects as well as domain boundaries similar to those described for inorganic and macromolecular crystals were identified. For several Bacillus species rodlet structure assembly and architectural variation appear to be a consequence of species-specific nucleation and crystallization mechanisms that regulate the formation of the outer spore coat. We propose a unifying mechanism for nucleation and self-assembly of this crystalline layer on the outer spore coat surface.

[Biodiversity and activity of the microbial community in the Kotelnikovsky Hot Springs (Lake Baikal)]

Complex microbiological and chemical analyses of water and bacterial mats were performed in the Kotelnikovsky Hot Springs (Lake Baikal). Transmission electron microscopy demonstrated that short rods about 1.2-2 microm in diameter predominated in the natural microbial community. Scanning electron microscopy coupled with chemical analysis revealed a characteristic P peak in the bacteria-like mineral particles, which suggests their biogenic origin. Most strains of the thermophilic microorganisms were gram-positive spore-forming rods and can be assigned to the genus Bacillus. Assays for potential enzyme activity demonstrated that most of the strains tested were active at high temperature. The data obtained suggest high activity of the bacterial community in situ and its particular role in the functioning of the hydrothermal ecosystem.

Morphological and phenotypical characterization of Bacillus sporothermodurans

AIMS

Enumeration of resistant bacteria in ultra-high temperature (UHT) treated milk; morphological characterization and phenotyping of resistant strains by traditional and nontraditional methods and their identification by molecular biology.

METHODS AND RESULTS

Modified standard plate count agar (PCA) and modified brain-heart infusion (BHI) agar were used for colony counts. Physiological culture traits were determined as suggested by Bergey's Manual of Systematic Bacteriology or in modified J-broth or in modified BHI agar. Scanning electron microscope (SEM) was used for microscopic examination. Strain identification was carried out by polymerase chain reaction (PCR). A total of 125 (62.81% of 199) samples were positive and the bacterial load was higher than 10(5) CFU ml(-1) in 46 samples (28.80% of 125). The 16S rRNA sequence of bacterial cultures obtained from UHT-treated milk was similar to that of Bacillus sporothermodurans M215 type strain((T)) and different biotypes were found by analysis of colony appearance, cell morphology and physiological traits.

CONCLUSIONS

Bacillus sporothermodurans was the predominant sporigenous micro-organisms in UHT milk.

SIGNIFICANCE AND IMPACT OF THE STUDY

BHI agar is more suitable than PCA for quality control of milk after UHT treatment. Modified J-broth medium is useful to determine selected physiological traits of B. sporothermodurans. The strains characterized and identified as B. sporothermodurans were significantly different compared with the type strain.

Bacillus globigii Bugbeads: A Model Simulant of a Bacterial Spore

Nonpathogenic microorganisms are often used as simulants of biological pathogens during the initial phase of detection method development. While these simulants approximate the size, shape, and cellular organization of the microorganism of interest, they do not resemble its surface protein content, a factor particularly important in methods based on immunorecognition. Here, we develop and detect an artificial bacterial spore--B. globigii (BG) Bugbead-a particle mimicking the antigenic surface of BG spores. Two methods of spore protein extraction were compared both quantitatively (by protein concentration assay) and qualitatively (by SDS-PAGE and Western blot): extraction by mechanical disruption and extraction by chemical decoating. The former method was more efficient in producing more protein and a greater number of antigens. BG Bugbeads were made by conjugating the extracted proteins to 0.8-microm carboxyl-coated polystyrene particles via carbodiimide coupling. BG Bugbeads were successfully detected by a bead-based enzyme-labeled immunoassay with fluorescence detection with a detection limit of 6.9 x 10(3) particles/mL. Formation of the Bugbead-capture bead complex was confirmed by ESEM. The concept of a harmless artificial spore can be applied to developing improved simulants for pathogenic spore-forming microorganisms such as B. anthracis, C. botulinum, and B. cereus, which can to be used for method validation, instrument calibration, and troubleshooting.

Complete sequences of small acid-soluble proteins from Bacillus globigii

Three abundant small acid-soluble proteins (SASPs) from spores of Bacillus globigii were sequenced using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with post-source decay and nanoelectrospray collision-induced dissociation tandem mass spectrometry. The proteins were extracted from spores with 1 M HCl. Scanning electron micrographs of spores before and after acid extraction show that the spores retain their overall structure but have a shriveled texture following the acid treatment. Extracted SASPs were purified by high-performance liquid chromatography and molecular masses of the SASPs were identified at 7068 (SASP-1), 7332 (SASP-2), and 8889 (gamma-SASP). De novo peptide sequencing was used to determine the protein sequences. The correct ordering of peptide sequences was aided by mapping overlapping enzymatic digests and by comparison with homologous SASPs from Bacillus stearothermophilus. B. globigii is used in many field tests as a surrogate for B. anthracis. Thus complete SASP sequences from B. globigii will facilitate the development of methods for rapid identification of bacteria based on mass spectrometry and the examination of taxonomic relationships between Bacillus species.

[Identification and catalytic properties of Mg2+-dependent ATP-hydrolase of cytoplasmic membrane of Bacillus sp. B4253 capable of gold accumulation]

Ca2+-independent, Mg2+-dependent ATP-hydrolase fermentative activity consisting of two components--azide-sensitive and azide-resistant ones has been identified in cytoplasmic membrane of Bacillus sp. B4253 capable to gold accumulation in ionic and colloid forms. The authors have characterized properties of the azide-resistant component of ATP-hydrolase reaction: dynamics of accumulation of one of the reaction products--inorganic phosphate P(i); dependence of ATP hydrolysis rate on the membrane protein content; pH-dependence; sensitivity of ATP-hydrolase activity to the change of reagents (ATP, Mg2+) concentration, as well as to the effect of some specific and nonspecific inhibitors of ion-transporting Mg2+-dependent ATP-hydrolase systems (ouabain, tapsigargin, eocine Y, La ions). It is supposed that the obtained experimental data can be used for the following study of molecular and membrane mechanisms of gold accumulation in Bacillus sp. B4253.