Analysis of single-cell microbial mass spectra profiles from single-particle aerosol mass spectrometry

RATIONALE

Single-particle aerosol mass spectrometry is a practical method for studying microbial aerosols. However, the related mass spectral characteristics of single-cell microorganisms have not yet been studied systematically; hence, further investigations are necessary.

METHODS

Different microbial cells were grown and directly aerosolized in the laboratory. These aerosols were then drawn into a single-particle mass spectrometer platform, and single-cell mass spectra profiles were obtained in real-time. The biological characteristics, ion variation trends, and microbial types were analyzed with either laser pulse energy or laser fluence.

RESULTS

The single-particle mass spectra contained prominent peaks that could be attributed to the presence of biological matter, such as organic phosphate and nitrogen, amino acids, and spore-associated calcium complexes. Limited types of average mass spectral patterns were present, and a significant correlation was found between the ion intensity trend (presence and absence of peaks) and laser ionization energy (expressed by the total positive ion intensity). Although a single spectral data point does not contain all the peaks of the average spectrum, it covers most of the characteristic peaks and could be identified using a machine learning algorithm. After the analysis of single-particle mass spectra, we found that using multi-group features (e.g., peak intensity ratio of m/z +47 and +41, peak intensity ratio of ⁵⁹ N(CH₃ )₃ ⁺ and ⁷⁴ N(CH₃ )₄ ⁺ , and 12 peak variables) led to an identification accuracy of approximately 92.4% with the random forest algorithm.

CONCLUSIONS

The results indicate that single-cell mass spectral profiles can be used to distinguish microbial aerosols and further illustrate their origin in a laboratory setting.

Analysis of disulphide bond linkage between CoA and protein cysteine thiols during sporulation and in spores of Bacillus species

Spores of Bacillus species have novel properties, which allow them to lie dormant for years and then germinate under favourable conditions. In the current work, the role of a key metabolic integrator, coenzyme A (CoA), in redox regulation of growing cells and during spore formation in Bacillus megaterium and Bacillus subtilis is studied. Exposing these growing cells to oxidising agents or carbon deprivation resulted in extensive covalent protein modification by CoA (termed protein CoAlation), through disulphide bond formation between the CoA thiol group and a protein cysteine. Significant protein CoAlation was observed during sporulation of B. megaterium, and increased largely in parallel with loss of metabolism in spores. Mass spectrometric analysis identified four CoAlated proteins in B. subtilis spores as well as one CoAlated protein in growing B. megaterium cells. All five of these proteins have been identified as moderately abundant in spores. Based on these findings and published studies, protein CoAlation might be involved in facilitating establishment of spores' metabolic dormancy, and/or protecting sensitive sulfhydryl groups of spore enzymes.

Light-Driven ATP Regeneration in Diblock/Grafted Hybrid Vesicles

Light-driven ATP regeneration systems combining ATP synthase and bacteriorhodopsin have been proposed as an energy supply in the field of synthetic biology. Energy is required to power biochemical reactions within artificially created reaction compartments like protocells, which are typically based on either lipid or polymer membranes. The insertion of membrane proteins into different hybrid membranes is delicate, and studies comparing these systems with liposomes are needed. Here we present a detailed study of membrane protein functionality in different hybrid compartments made of graft polymer PDMS-g-PEO and diblock copolymer PBd-PEO. Activity of more than 90 % in lipid/polymer-based hybrid vesicles could prove an excellent biocompatibility. A significant enhancement of long-term stability (80 % remaining activity after 42 days) could be demonstrated in polymer/polymer-based hybrids.

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.

A genetically encoded single-wavelength sensor for imaging cytosolic and cell surface ATP

Adenosine 5' triphosphate (ATP) is a universal intracellular energy source and an evolutionarily ancient, ubiquitous extracellular signal in diverse species. Here, we report the generation and characterization of single-wavelength genetically encoded fluorescent sensors (iATPSnFRs) for imaging extracellular and cytosolic ATP from insertion of circularly permuted superfolder GFP into the epsilon subunit of F0F1-ATPase from Bacillus PS3. On the cell surface and within the cytosol, iATPSnFR1.0 responds to relevant ATP concentrations (30 μM to 3 mM) with fast increases in fluorescence. iATPSnFRs can be genetically targeted to specific cell types and sub-cellular compartments, imaged with standard light microscopes, do not respond to other nucleotides and nucleosides, and when fused with a red fluorescent protein function as ratiometric indicators. After careful consideration of their modest pH sensitivity, iATPSnFRs represent promising reagents for imaging ATP in the extracellular space and within cells during a variety of settings, and for further application-specific refinements.

Single bacteria movement tracking by online microscopy--a proof of concept study

In this technical report we demonstrate a low-cost online unit allowing movement tracking of flagellated bacteria on a single-cell level during fermentation processes. The system's ability to distinguish different metabolic states (viability) of bacteria by movement velocity was investigated. A flow-through cuvette with automatically adjustable layer thickness was developed. The cuvette can be used with most commercially available laboratory microscopes equipped with 40× amplification and a digital camera. In addition, an automated sample preparation unit and a software module was developed measuring size, moved distance, and speed of bacteria. In a proof of principle study the movement velocities of Bacillus amyloliquefaciens FZB42 during three batch fermentation processes were investigated. In this process the bacteria went through different metabolic states, vegetative growth, diauxic shift, vegetative growth after diauxic shift, and sporulation. It was shown that the movement velocities during the different metabolic states significantly differ from each other. Therefore, the described setup has the potential to be used as a bacteria viability monitoring tool. In contrast to some other techniques, such as electro-optical techniques, this method can even be used in turbid production media.

Biotransformation of various saccharides and production of exopolymeric substances by cloud-borne Bacillus sp. 3B6

The ability of Bacillus sp. 3B6, a bacterial strain isolated from cloudwaters, to biotransform saccharides present in the atmosphere was evaluated using in situ 1D and 2D NMR spectroscopy. Bacillus is one of the genera most frequently described in the air and in atmospheric waters. Sugars present in these environments have a biogenic origin; they include alditols, monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Bacillus sp. 3B6 was able to efficiently metabolize sugars, which could thus provide sources of energy for this bacterium and allow it to live and to be metabolically active in warm clouds. In addition, a number of these saccharides (L-arabitol, D-fructose, sucrose, D-glucose, cellotetraose, cellulose, and starch) were transformed to EPSs (exopolymeric substances). We have clearly identified the structure of two EPSs as 1,6-α-galactan and partially acetylated polyethylene glycol. 1,6-α-Galactan is a newly described polymer. The production of EPSs might protect this bacterium under hostile cloud environment conditions, including low nutrient availability, cold temperature and freeze-thaw processes, UV and radical exposure, and evaporation-condensation processes and thus desiccation and osmolarity changes. EPSs could also have a potential role in atmospheric processes because they can be considered as secondary organic aerosols and efficient cloud condensation nuclei.

Bacillus spores as building blocks for stimuli-responsive materials and nanogenerators

Materials that respond mechanically to external chemical stimuli have applications in biomedical devices, adaptive architectural systems, robotics and energy harvesting. Inspired by biological systems, stimuli-responsive materials have been created that can oscillate, transport fluid, provide homeostasis and undergo complex changes in shape. However, the effectiveness of synthetic stimuli-responsive materials in generating work is limited when compared with mechanical actuators. Here, we show that the mechanical response of Bacillus spores to water gradients exhibits an energy density of more than 10 MJ m(-3), which is two orders of magnitude higher than synthetic water-responsive materials. We also identified mutations that can approximately double the energy density of the spores and found that they can self-assemble into dense, submicrometre-thick monolayers on substrates such as silicon microcantilevers and elastomer sheets, creating bio-hybrid hygromorph actuators. To illustrate the potential applications of the spores, we used them to build an energy-harvesting device that can remotely generate electrical power from an evaporating body of water.

A sputum smear microscopy image database for automatic bacilli detection in conventional microscopy

In this work, we present an image database for automatic bacilli detection in sputum smear microscopy. The database comprises two parts. The first one, called the autofocus database, contains 1200 images with resolution of 2816 × 2112 pixels. This database was obtained from 12 slides, with 10 fields per slide. Each stack is composed of 10 images, with the fifth image in focus. The second one, called the segmentation and classification database, contains 120 images with resolution of 2816×2112 pixels. This database was obtained from 12 slices, with 10 fields per slice. In both databases, the images were acquired from fields of slides stained with the standard Kinyoun method. In both databases, accordingly to the background content, the images were classified as belonging to high background content or low background content. In all 120 images of segmentation and classification database, the identified objects were enclosed within a geometric shape by a trained technician. A true bacillus was enclosed in a circle. An agglomerated bacillus was enclosed by a rectangle and a doubtful bacillus (the image focus or geometry does not allow a clear identification of the object) was enclosed by a polygon. These marked objects could be used as a gold standard to calculate the accuracy, sensitivity and specificity of bacilli recognition.

Ultrasound stimulated production of a fibrinolytic enzyme

The present study is aimed at enhanced production of a fibrinolytic enzyme from Bacillus sphaericus MTCC 3672 under ultrasonic stimulation. Various process parameters viz; irradiation at different growth phases, ultrasonication power, irradiation duration, duty cycle and multiple irradiation were studied for enhancement of fibrinolytic enzyme productivity. The optimum conditions were found as follows, irradiation of ultrasonic waves to fermentation broth at 12 h of growth phase with 25 kHz frequency, 160 W ultrasound power, 20% duty cycle for 5 min. The productivity of fibrinolytic enzyme was increased 1.82-fold from 110 to 201 U/mL compared with the non sonicated control fermentation. Drop in glucose concentration from 0.41% to 0.12% w/v in ultrasonicated batch implies that, ultrasonication increases the cell permeability, improves substrate intake and progresses metabolism of microbial cell. Microscopic images before and after ultrasonic stimulation clearly signifies the impact of duty cycle on decreasing biomass concentration. However, environmental scanning electron micrograph does not show any cell lysis at optimum ultrasonic irradiation. Offshoots of our results will contribute to fulfill the demand of enhancement of microbial therapeutic enzyme productivity, through ultrasonication stimulation.

Open fermentative production of L-lactic acid with high optical purity by thermophilic Bacillus coagulans using excess sludge as nutrient

The development of a low-cost polymer-grade L-lactic acid production process was achieved in this study. Excess sludge hydrolyzate (ESH) was chosen as nutrient source for the objective of reducing nutrient cost in lactic acid production. 1% of ESH had high performance in lactic acid production relative to 2g/l yeast extract (YE) while the production cost of ESH was much lower than that of YE, indicating ESH was a promising substitute of YE. By employing a thermophilic strain of Bacillus coagulans (NBRC 12583), non-sterilized batch and repeated batch L-lactic acid fermentation was successfully performed, and the optical purity of L-lactic acid accumulated was more than 99%. Moreover, the factors associated with cell growth and lactic acid fermentation was investigated through a two-stage lactic acid production strategy. Oxygen played an important role in cell growth, and the optimal condition for cell growth and fermentation was pH 7.0 and 50°C.

The ComP-ComA quorum system is essential for "Trojan horse" like pathogenesis in Bacillus nematocida

Bacillus nematocida B16 has been shown to use “Trojan horse” mechanism in pathogenesis that has characteristics of “social” behavior. The ComP-ComA system, a conserved quorum sensing system in the genus Bacillus, functions in many physiological processes including competence development, lipopeptide antibiotic surfactin production, degradative enzyme production and even some unknown functions. Here we investigated the requirement of ComP-ComA system in B. nematocida B16 for its pathogenicity against nematodes. The ΔcomP mutant displayed deficiencies in attracting and killing nematodes, due to the absence of attractive signal molecules and the decreased expressions of virulence factors, respectively. Contrarily, a complemented comP mutant at least partially resumed its pathogenicity. Our data from transcriptional analysis further confirmed that this signaling system directly or indirectly regulated the expressions of two major virulence proteases in the infection of B. nematocida B16. Bioinformatics analyses from comparative genomics also suggested that the potential target genes of transcription factor ComA were involved in the processes such as the synthesis of attractants, production of extracellular degradative enzymes and sortase, secondary metabolites biosynthesis, regulation of transcription factors, mobility, as well as transporters, most of which were different from a saprophytic relative B. subtilis 168. Therefore, our investigation firstly revealed that the participation and necessity of ComP-ComA signaling system in bacterial pathogenesis.

Curing the plasmid pMC1 from the poly (γ-glutamic acid) producing Bacillus amyloliquefaciens LL3 strain using plasmid incompatibility

Bacillus amyloliquefaciens LL3 is a glutamate-independent poly-γ-glutamic acid (γ-PGA) producing strain which consists of a circular chromosome (3,995,227 bp) and an endogenous plasmid pMC1 (6,758 bp). The study of the function of native plasmid and the genome-size reduction of the B. amyloliquefaciens LL3 strain requires elimination of the endogenous plasmid. Traditional plasmid-curing procedures using sodium dodecyl sulfate (SDS) or acridine orange combined with heat treatment have been shown to be ineffective in this strain. Plasmid incompatibility is an effective method for curing which has been studied before. In our research, the hypothetical Rep protein gene and the origin of replication of the endogenous plasmid were cloned into the temperature-sensitive vector yielding the incompatible plasmid pKSV7-rep-ori. This plasmid was transformed into LL3 by electroporation. The analysis of the strain bearing incompatible plasmids after incubation at 30 °C for 30 generations showed the production of plasmid cured strains. High frequency of elimination was achieved with more than 93 % of detected strains showing to be plasmid-cured. This is the first report describing plasmid cured in a γ-PGA producing strain using this method. The plasmid-cured strains showed an increase of γ-PGA production by 6 % and led to a yield of 4.159 g/l, compared to 3.918 g/l in control and cell growth increased during the early stages of the exponential phase. Gel permeation chromatography (GPC) characterization revealed that the γ-PGA produced by plasmid-cured strains and the wild strains were identical in terms of molecular weight. What is more, the further study of plasmid function showed that curing of the endogenous plasmid did not affect its sporulation efficiency.

Use of microcapsules with electrostatically immobilized bacterial cells or enzyme extract to remove nonylphenol in wastewater sludge

We investigated the use of a high-voltage electrostatic system to immobilize bacterial cells or enzyme extract in alginate microcapsules for removing nonylphenol (NP) from wastewater sludge. With applied potential increased from 0 to 12kV, the gel bead diameter decreased from 950 to 250 μm. The amount of bacterial cells or enzyme extract immobilized in alginate microcapsules was greater than that in suspension, for improved tolerance to environmental loadings. Removal of NP at 2.0-20.0 mg L(-1) was greater with extract- than cell-containing microcapsules. The percentage of toxic chemicals (2.0 mg L(-1)) removed with alginate microcapsules, in descending order of magnitude, was bisphenol-F>bisphenol-A>NP>oxytetracycline>chlortetracycline>tetracycline>dibromodiphenyl ethers>tetrabromobisphenol-A>decabromodiphenyl ether.

Pigmentation and sporulation are alternative cell fates in Bacillus pumilus SF214

Bacillus pumilus SF214 is a spore forming bacterium, isolated from a marine sample, able to produce a matrix and a orange-red, water soluble pigment. Pigmentation is strictly regulated and high pigment production was observed during the late stationary growth phase in a minimal medium and at growth temperatures lower than the optimum. Only a subpopulation of stationary phase cells produced the pigment, indicating that the stationary culture contains a heterogeneous cell population and that pigment synthesis is a bimodal phenomenon. The fraction of cells producing the pigment varied in the different growth conditions and occured only in cells not devoted to sporulation. Only some of the pigmented cells were also able to produce a matrix. Pigment and matrix production in SF214 appear then as two developmental fates both alternative to sporulation. Since the pigment had an essential role in the cell resistance to oxidative stress conditions, we propose that within the heterogeneous population different survival strategies can be followed by the different cells.

CotA, a multicopper oxidase from Bacillus pumilus WH4, exhibits manganese-oxidase activity

Multicopper oxidases (MCOs) are a family of enzymes that use copper ions as cofactors to oxidize various substrates. Previous research has demonstrated that several MCOs such as MnxG, MofA and MoxA can act as putative Mn(II) oxidases. Meanwhile, the endospore coat protein CotA from Bacillus species has been confirmed as a typical MCO. To study the relationship between CotA and the Mn(II) oxidation, the cotA gene from a highly active Mn(II)-oxidizing strain Bacillus pumilus WH4 was cloned and overexpressed in Escherichia coli strain M15. The purified CotA contained approximately four copper atoms per molecule and showed spectroscopic properties typical of blue copper oxidases. Importantly, apart from the laccase activities, the CotA also displayed substantial Mn(II)-oxidase activities both in liquid culture system and native polyacrylamide gel electrophoresis. The optimum Mn(II) oxidase activity was obtained at 53°C in HEPES buffer (pH 8.0) supplemented with 0.8 mM CuCl2. Besides, the addition of o-phenanthroline and EDTA both led to a complete suppression of Mn(II)-oxidizing activity. The specific activity of purified CotA towards Mn(II) was 0.27 U/mg. The Km, Vmax and kcat values towards Mn(II) were 14.85±1.17 mM, 3.01×10(-6)±0.21 M·min(-1) and 0.32±0.02 s(-1), respectively. Moreover, the Mn(II)-oxidizing activity of the recombinant E. coli strain M15-pQE-cotA was significantly increased when cultured both in Mn-containing K liquid medium and on agar plates. After 7-day liquid cultivation, M15-pQE-cotA resulted in 18.2% removal of Mn(II) from the medium. Furthermore, the biogenic Mn oxides were clearly observed on the cell surfaces of M15-pQE-cotA by scanning electron microscopy. To our knowledge, this is the first report that provides the direct observation of Mn(II) oxidation with the heterologously expressed protein CotA, Therefore, this novel finding not only establishes the foundation for in-depth study of Mn(II) oxidation mechanisms, but also offers a potential biocatalyst for Mn(II) removal.

Heavy metal toxicity to bacteria - are the existing growth media accurate enough to determine heavy metal toxicity?

A new minimal medium was formulated considering the limitations of the existing media for testing heavy metal sensitivity to bacteria. Toxicity of cadmium and copper to three bacteria was investigated in the new medium and compared with three other media commonly used to study the effect of the toxic metals. Based on speciation data arrived at using ion-selective electrodes, the available free-metal concentration in solution was highest in the MES-buffered medium. This finding was strongly supported by the estimated EC(50) values for the metals tested based on the toxicity bioassays. The free-ionic cadmium and copper concentrations in the medium provide more accurate determination of metal concentrations that affects the bacteria, than with most of other existing media. This will avoid doubts on other media and misleading conclusions relevant to the toxicity of heavy metals to bacteria and provides a better option for the study of metal-bacteria interactions.

Preservation of Bacillus firmus strain 37 and optimization of cyclodextrin biosynthesis by cells immobilized on loofa sponge

The preservation of Bacillus firmus strain 37 cells by lyophilization was evaluated and response surface methodology (RSM) was used to optimize the β-cyclodextrin (β-CD) production by cells immobilized on loofa sponge. Interactions were studied with the variables temperature, pH and dextrin concentration using a central composite design (CCD). Immobilization time influence on β-CD production was also investigated. B. firmus strain 37 cells remained viable after one year of storage, showing that the lyophilization is a suitable method for preservation of the microorganism. From the three-dimensional diagrams and contour plots, the best conditions for β-CD production were determined: temperature 60 °C, pH 8, and 18% dextrin. Considering that the amount of dextrin was high, a new assay was carried out, in which dextrin concentrations of 10, 15, and 18% were tested and the temperature of 60 °C and pH 8 were maintained. The results achieved showed very small differences and therefore, for economic reasons, the use of 10% dextrin is suggested. Increasing the immobilization time of cells immobilized on synthetic sponge the β-CD production decreased and did not change for cells immobilized on loofa sponge. The results of this research are important for microorganism preservation and essential in the optimization of the biosynthesis of CD.

A catalase-peroxidase for oxidation of β-lactams to their (R)-sulfoxides

In this communication we report for the first time a biocatalytic method for stereoselective oxidation of β-lactams, represented by penicillin-G, penicillin-V and cephalosporin-G to their (R)-sulfoxides. The method involves use of a bacterium, identified as Bacillus pumilis as biocatalyst. The enzyme responsible for oxidase activity has been purified and characterized as catalase-peroxidase (KatG). KatG of B. pumilis is a heme containing protein showing characteristic heme spectra with soret peak at 406 nm and visible peaks at 503 and 635 nm. The major properties that distinguish B. pumilis KatG from other bacterial KatGs are (i) it is a monomer and contains one heme per monomer, whereas KatGs of other bacteria are dimers or tetramers and have low heme content of about one per dimer or two per tetramer and (ii) its 12-residue, N-terminal sequence obtained by Edman degradation did not show significant similarity with any of known KatGs.

Rapid detection of viable Bacillus pumilus SAFR-032 encapsulated spores using novel propidium monoazide-linked fluorescence in situ hybridization

The survival of Bacillus pumilus SAFR-032 spores to standard industrial clean room sterilization practices necessitates the development of rapid molecular diagnostic tool(s) for detection and enumeration of viable bacterial spores in industrial clean room environments. This is of importance to maintaining the sterility of clean room processing products. This paper describes the effect of propidium monoazide (PMA) on fluorescence in situ hybridization (FISH) for detecting and enumerating B. pumilus SAFR-032 viable spores having been artificially encapsulated within poly(methylmethacrylate) (Lucite, Plexiglas) and released via an organic solvent (PolyGone-500). The results of the PMA-FISH experiments discussed herein indicate that PMA was able to permeate only the compromised coat layers of non-viable spores, identifying PMA treatment of bacterial spores prior to FISH analysis as a novel method for selecting out the fraction of the spore population that is non-viable from fluorescence detection. The ability of novel PMA-FISH to selectively distinguish and enumerate only the living spores present in a sample is of potential significance for development of improved strategies to minimize spore-specific microbial burden in a given environment.

Biodegradation of lipids from olive oil mill wastewaters in a stationary basket bioreactor with immobilized Bacillus spp. cells - influence of internal diffusion

The study is focused on the external and internal mass transfers of lipids during their biodegradation process in a bioreactor with stationary basket bed of immobilized Bacillus spp. cells. By means of the lipid mass balance for a single particle of biocatalyst, considering the kinetic model adapted for the immobilized bacterial cells, specific mathematical models have been developed to estimate their mass flows in the liquid boundary layer surrounding the particle and inside the particle. The values of mass flows are significantly influenced by the internal diffusion velocity of lipids and the rate of their consumption, but also by the position inside the basket bed. These influences accumulated led to the appearance of a biological inactive region near the particle centre, its magnitude varying from 1.3 to 49.4% of the overall volume of particles.

An improved bioprocess for synthesis of acetohydroxamic acid using DTT (dithiothreitol) treated resting cells of Bacillus sp. APB-6

Acyltransferase activity of amidase from Bacillus sp. APB-6 was enhanced (24 U) by multiple feedings of N-methylacetamide (70 mM) into the production medium. Hyperinduced whole resting cells of Bacillus sp. APB-6 corresponding to 4 g/L (dry cell weight), when treated with 10mM DTT (dithiothreitol) resulted in 93% molar conversion of acetamide (300 mM) to acetohydroxamic acid in presence of hydroxylamine-HCl (800 mM) after 30 min at 45°C in a 1L reaction mixture. After lyophilization, a 62 g powder containing 34% (wtwt(-1)) acetohydroxamic acid was recovered. This is the first report where DTT has been used to enhance acyltransfer reaction and such high molar conversion (%) of amide to hydroxamates was recorded at 1L scale.

Isolation and characterization of a metal ion-dependent alkaline protease from a halotolerant Bacillus aquimaris VITP4

A halotolerant bacterium Bacillus acquimaris VITP4 was used for the production of extracellular protease. Fractional precipitation using ammonium chloride was used to obtain the enzyme. The protease exhibited optimum activity at pH 8.0 and 40 degrees C and retained 50% of its optimal proteolytic activity even in the presence of 4 M NaCl, suggesting that it is halotolerant. The molecular mass of protease, as revealed by SDS-PAGE was found to be 34 kDa and the homogeneity of the enzyme was confirmed by gelatin zymography and reverse-phase HPLC. Upon purification, the specific activity of th enzyme increased from 533 U/mg to 1719 U/mg. Protease inhibitors like phenyl methane sulphonyl fluoride and 2-mercaptoethanol did not affect the activity of the enzyme, but EDTA inhibited the activity, indicating the requirement of metal ions for activity. Cu2, Ni2+ and Mn2+ enhanced the enzyme activity, but Zn2+, Hg2+ and Fe2+ decreased the activity, while Mg2+, Ca2+ and K+ had no effect on the enzyme activity. The protease was quite stable in the presence of cationic (CTAB), anionic (SDS) and neutral detergents (Triton X-100 and Tween-20) and exhibited antimicrobial activity against selected bacterial and fungal strains. The stability characteristics and broad spectrum antimicrobial activity indicated the potential use of this protease in industrial applications.

Genomic signatures of strain selection and enhancement in Bacillus atrophaeus var. globigii, a historical biowarfare simulant

BACKGROUND

Despite the decades-long use of Bacillus atrophaeus var. globigii (BG) as a simulant for biological warfare (BW) agents, knowledge of its genome composition is limited. Furthermore, the ability to differentiate signatures of deliberate adaptation and selection from natural variation is lacking for most bacterial agents. We characterized a lineage of BGwith a long history of use as a simulant for BW operations, focusing on classical bacteriological markers, metabolic profiling and whole-genome shotgun sequencing (WGS).

RESULTS

Archival strains and two "present day" type strains were compared to simulant strains on different laboratory media. Several of the samples produced multiple colony morphotypes that differed from that of an archival isolate. To trace the microevolutionary history of these isolates, we obtained WGS data for several archival and present-day strains and morphotypes. Bacillus-wide phylogenetic analysis identified B. subtilis as the nearest neighbor to B. atrophaeus. The genome of B. atrophaeus is, on average, 86% identical to B. subtilis on the nucleotide level. WGS of variants revealed that several strains were mixed but highly related populations and uncovered a progressive accumulation of mutations among the "military" isolates. Metabolic profiling and microscopic examination of bacterial cultures revealed enhanced growth of "military" isolates on lactate-containing media, and showed that the "military" strains exhibited a hypersporulating phenotype.

CONCLUSIONS

Our analysis revealed the genomic and phenotypic signatures of strain adaptation and deliberate selection for traits that were desirable in a simulant organism. Together, these results demonstrate the power of whole-genome and modern systems-level approaches to characterize microbial lineages to develop and validate forensic markers for strain discrimination and reveal signatures of deliberate adaptation.

Reversible removal of SO2 at low temperature by Bacillus licheniformis immobilized on γ-Al2O3

Bacillus licheniformis R08 biomass was immobilized on γ-Al2O3 and the effects of R08 biomass loading, SO2 concentration, water vapor, oxygen and temperature on removal of SO2 were investigated. The experimental results indicated that SO2 saturation capacity increased with increasing R08 biomass loading and SO2 concentration, but decreased with increasing adsorption temperature. Water vapor activated the adsorbent and promoted SO2 removal. An increase in oxygen concentration from 5 to 10% had little effect on SO2 removal. FTIR analysis revealed that the R08 biomass bound to γ-Al2O3 mainly by forming R-CO-O-Al bonds. X-ray photoelectron spectroscopy analysis indicated that γ-Al2O3 reacted with SO2 and formed aluminum sulfate in the presence of oxygen when R08 biomass loading was 13.8%, but that amido groups of the R08 biomass reacted with SO2 and formed sulfite when biomass loading was 32.4%. Ten continuous adsorption-desorption cycles showed that the adsorbent had an excellent regeneration performance.

An artificial intelligence approach to Bacillus amyloliquefaciens CCMI 1051 cultures: application to the production of anti-fungal compounds

The combined effect of incubation time (IT) and aspartic acid concentration (AA) on the predicted biomass concentration (BC), Bacillus sporulation (BS) and anti-fungal activity of compounds (AFA) produced by Bacillus amyloliquefaciens CCMI 1051, was studied using Artificial Neural Networks (ANNs). The values predicted by ANN were in good agreement with experimental results, and were better than those obtained when using Response Surface Methodology. The database used to train and validate ANNs contains experimental data of B. amyloliquefaciens cultures (AFA, BS and BC) with different incubation times (1-9 days) using aspartic acid (3-42 mM) as nitrogen source. After the training and validation stages, the 2-7-6-3 neural network results showed that maximum AFA can be achieved with 19.5 mM AA on day 9; however, maximum AFA can also be obtained with an incubation time as short as 6 days with 36.6 mM AA. Furthermore, the model results showed two distinct behaviors for AFA, depending on IT.

Production of L-lactic acid by a thermophilic Bacillus mutant using sodium hydroxide as neutralizing agent

A sodium lactate tolerant mutant strain named Bacillus sp. Na-2 was obtained and applied to sodium hydroxide-based L-lactic acid (LA) production process. The influences of aeration and pH were investigated to further improve the resistance of strain Na-2 against sodium lactate stress and to obtain the most efficient L-LA production process. Although mild aeration was favorable for cell growth and L-LA production, vigorous aeration resulted in a metabolic shift from homolactic to mixed-acid/acetoin fermentation. Therefore, a two-stage aeration control strategy was employed. Optimum pH was found to be 6.0. A total of 106.0 g/l L-LA was produced in 30 h by Bacillus sp. Na-2 using sodium hydroxide as neutralizing agent. Productivity, conversion rate and optical purity were 3.53 g/l/h, 94% and 99.5%, respectively. The remarkable fermentation traits of Bacillus sp. Na-2 and the environment-friendly characteristics of NaOH-based process represent new insight for industrial scale production of L-LA.

Cloning, sequence analysis, and expression of a gene encoding an endoxylanase from Bacillus halodurans S7

The gene encoding an alkaline active xylanase of Bacillus halodurans S7, containing an open reading frame of 1188 nucleotides encoding 396 amino acids, was cloned and expressed in Escherchia coli. On the basis of sequence similarity, possible -10 and -35, ribosome binding, and transcription terminator regions were identified. Analysis of the deduced amino acid sequence revealed that the protein was a single domain enzyme belonging to family 10 and designated as xyn10A. The calculated molecular mass and isoelectric point (pI) of the mature peptide were 42.6 and 4.5 kDa, respectively. Xylanase activity expressed by the recombinant organism was detected in the cytoplasm, periplasm and the extracellular medium. In an 18-h old culture, about 39% of the xylanase was detected in the medium. The stability and activity profile of the recombinant xylanase was similar to the properties of the enzyme produced by the wild-type organism.

First solid state alkaline-earth complexes of monensic acid A (MonH): crystal structure of [M(Mon)2(H (2)O)2] (M = Mg, Ca), spectral properties and cytotoxicity against aerobic Gram-positive bacteria

Alkaline-earth metal complexes of the monoanionic form of the polyether ionophore monensin A were isolated for the first time in solid state and were structurally characterized using various spectroscopic methods (IR, NMR, FAB-MS). The stoichiometric reaction of monensic acid (MonH) with M(2+) (M = Mg, Ca) in the presence of an organic base leads to the formation of mononuclear complexes of composition [M(Mon)(2)(H(2)O)(2)]. The structures of magnesium (1) and calcium (2) monensin complexes in the solid state were established by single crystal X-ray crystallography. The complexes crystallize as [Mg(Mon)(2)(H(2)O)(2)]x5MeCN (1) and [Ca(Mon)(2)(H(2)O)(2)]xH(2)Ox5MeCN (2) in the monoclinic P21 space group. The alkaline-earth metal ion is placed in a distorted octahedral environment, defined by two monensin anions acting as bidentate ligands in the equatorial plane of the complex as well as by two water molecules occupying the axial positions of the inner coordination sphere. The bactericidal activity of 1 and 2 was evaluated against aerobic Gram-positive microorganisms applying the double layer agar hole diffusion method.

The infrared spectra of Bacillus bacteria part II: sporulated Bacillus--the effect of vegetative cells and contributions of calcium dipicolinate trihydrate, CaDP.3H2O

Our previous paper showed that certain infrared (IR) peaks, e.g., the peak at 1739 cm(-1), are due to varying (trace) amounts of vegetative cells amongst the Bacillus spores and that these and other vegetative bands are associated with lipid-soluble compounds, likely an ester or phospholipid. This work investigates the infrared spectra of eight different sporulated Bacillus bacteria. For the endospores it is observed that peaks at 1441, 1277, and 1015 cm(-1) along with a distinct quartet of peaks at 766, 725, 701, and 659 cm(-1) are clearly associated with calcium dipicolinate trihydrate, CaDP.3H2O. It is emphasized that the spore peaks, especially the quartet, arise from the calcium dipicolinate trihydrate and not from dipicolinic acid or other dipicolinate hydrate salts. The CaDP.3H2O infrared peaks and the effects of hydration are studied using quantum chemistry in the PQS software package. The quartet is associated with many modes including contributions from the Ca2+ counterion and hydration waters including Ca-O-H bends, H2O-Ca-O torsions, and O-C-O bends. The 1441 and 1015 cm(-1) modes are planar pyridine modes with the 1441 cm(-1) mode primarily a ring C-N stretch and the 1015 cm(-1) mode primarily a ring C-C stretch.

The infrared spectra of Bacillus bacteria part I: vegetative Bacillus versus sporulated cells and the contributions of phospholipids to vegetative infrared spectra

This paper highlights the distinctions between the infrared (IR) absorption spectra of vegetative versus sporulated Bacillus bacteria. It is observed that there are unique signatures clearly associated with either the sporulated or vegetative state and that vegetative cells (or cell debris) can contribute to the spore spectra. A distinct feature at approximately 1739 cm(-1) appears to be unique to vegetative cell spectra and can also be used as an indicator of vegetative cells or cell debris in the spore spectra. The data indicate that the band arises from a lipid-soluble species such as an ester or phospholipid carbonyl bond and are consistent with it being either phosphatidyl glycerol (PG) or phosphatidylethanolamine (PE), two major classes of phospholipids found in vegetative cells of Bacillus species. A companion work discusses bands associated with the sporulated state.

Computation of traveling wave fronts for a nonlinear diffusion-advection model

This paper utilizes a nonlinear reaction-diffusion-advection model for describing the spatiotemporal evolution of bacterial growth. The traveling wave solutions of the corresponding system of partial differential equations are analyzed. Using two methods, we then find such solutions numerically. One of the methods involves the traveling wave equations and solving an initial-value problem, which leads to accurate computations of the wave profiles and speeds. The second method is to construct time-dependent solutions by solving an initial-moving boundary-value problem for the PDE system, showing another approximation for such wave solutions.

Determination of lethality rate constants and D-values for Bacillus atrophaeus (ATCC 9372) spores exposed to dry heat from 115 degrees C to 170 degrees C

Dry heat microbial reduction is the NASA-approved sterilization method to reduce the microbial bioburden on spaceflight hardware for missions with planetary protection requirements. The method involves heating the spaceflight hardware to temperatures between 104 degrees C and 125 degrees C for up to 50 hours, while controlling the humidity to very low values. Collection of lethality data at temperatures above 125 degrees C and with ambient (uncontrolled) humidity conditions would establish whether any microbial reduction credit can be offered to the flight project for processes that occur at temperatures greater than 125 degrees C. The goal of this research is to determine the survival rates of Bacillus atrophaeus (ATCC 9372) spores subjected to temperatures higher than 125 degrees C under both dry (controlled) and room ambient humidity (36-66% relative humidity) conditions. Spores were deposited inside thin, stainless steel thermal spore exposure vessels (TSEVs) and heated under ambient or controlled humidity conditions from 115 degrees C to 170 degrees C. After the exposures, the TSEVs were cooled rapidly, and the spores were recovered and plated. Survivor ratios, lethality rate constants, and D-values were calculated at each temperature. At 115 degrees C and 125 degrees C, the controlled humidity lethality rate constant was faster than the ambient humidity lethality rate constant. At 135 degrees C, the ambient and controlled humidity lethality rate constants were statistically identical. At 150 degrees C and 170 degrees C, the ambient humidity lethality rate constant was slightly faster than the controlled humidity lethality rate constant. These results provide evidence for possibly modifying the NASA dry heat microbial reduction specification.

Genome shuffling of Lactobacillus delbrueckii mutant and Bacillus amyloliquefaciens through protoplasmic fusion for L-lactic acid production from starchy wastes

Current study was focused on the development of a non-fastidious lactic acid producing strain having better growth rate, low pH tolerance and good productivity by genome shuffling of a mutant strain of Lactobacillus delbrueckii NCIM 2025 and an amylase producing non-fastidious Bacillus amyloliquefaciens ATCC 23842. After the third cycle of the protoplast fusion, lactic acid production by few fusants was monitored and the best fusant was selected for further studies. Optimization of the important process parameters for lactic acid production was conducted using Plackett-Burman design and response surface methodology. Selected fusant could utilize the liquefied cassava bagasse starch directly with minimum nutrient supplementation for lactic acid production. During validation, 40g/L of lactic acid was obtained ( approximately 96% conversion of starch to lactic acid) by using fusant inoculum (3%, v/v) from 83g/L cassava bagasse (starch content 50% w/w) supplemented with yeast extract and peptone (0.2% each, w/v) and the buffering agent (2% CaCO3, w/v).

Alicyclobacillusspp. in the Fruit Juice Industry: History, Characteristics, and Current Isolation/Detection Procedures

The first Alicyclobacillus spp. was isolated in 1982, and was originally thought to be strictly limited to thermophilic and acidic environments. Two years later, another Alicyclobacillus sp., A. acidoterrestris, was identified as the causative agent in spoilage of commercially pasteurized apple juice. Subsequent studies soon found that Alicyclobacillus spp. are soilborne bacteria, and do not strictly require thermophilic and acidic environments. Alicyclobacillus spp. posess several distinct characteristics; the major one is their ability to survive commercial pasteurization processes and produce off-flavors in fruit juices. The fruit juice industry has acknowledged Alicyclobacillus spp. as a major quality control target microorganism. Guaiacol and halophenols were identified as the offensive smelling agent in many Alicyclobacillus spp. related spoilage. Though the exact formation pathway of these off-flavors by Alicyclobacillus spp. are not yet identified, studies report that the presence of Alicyclobacillus spp. in the medium may be a major contributor to the formation of these off-flavors. Many identification methods and isolation media were developed in the last two decades. However, most of these methods were developed specifically for A. acidoterrestris, which was the first identified off-flavor producing Alicyclobacillus. However, recent studies indicate that other species of Alicyclobacillus may also produce guaiacol or the halophenols. In this respect, all Alicyclobacillus spp. should be monitored as potential spoilage bacteria in fruit juices. This article includes an overall review of the history of Alicyclobacillus spp., characteristics, suggested off-flavor production pathways, and commonly used identification methods for the currently identified Alicyclobacillus spp.

[Multiplex-PCR approach to identify Bacillus species applied in microbial fertilizers]

OBJECTIVE

To discriminate the strains of Bacillus subtilis group including B. subtilis, B. amyloliquefaciens, B. licheniformis, and B. pumilus, a rapid and accurate distinguishing method is essential for the identification of the target strains to ensure the quality and safety of microbial fertilizers.

METHODS

By analyzing unique nucleotide sequences of the rpoA, gyrA and 16S rDNA genes, 4 pairs of species-specific primers were optimized and the multiplex PCR was developed to discriminate and identify B. subtilis, B. amyloliquefaciens, B. licheniformis and B. pumilus.

RESULTS

Thirty-three reference strains belonging to three genera of Bacillus, Paenibacillus and Brevibacillus were tested and the anticipated results appeared except for four species with cross amplification results with the primers of B. pumilus. However, the four species can be easily discriminated by morphology characters. In addition, the multiplex-PCR results of 23 strains of B. subtilis group isolated from MF products were identical with the biochemical assay.

CONCLUSION

The newly constructed multiplex-PCR assay is species-specific and effective. This method can be used to detect and identify the strains of B. subtilis group from microbial fertilizers products.

Characterization of acetanilide herbicides degrading bacteria isolated from tea garden soil

Three different green manures were added to the tea garden soils separately and incubated for 40 days. After, incubation, acetanilide herbicides alachlor and metolachlor were spiked into the soils, separately, followed by the isolation of bacteria in each soil at designed intervals. Several bacterial strains were isolated from the soils and identified as Bacillus silvestris, B. niacini, B. pseudomycoides, B. cereus, B. thuringiensis, B. simplex, B. megaterium, and two other Bacillus sp. (Met1 and Met2). Three unique strains with different morphologies were chosen for further investigation. They were B. megaterium, B. niacini, and B. silvestris. The isolated herbicide-degrading bacteria showed optimal performance among three incubation temperatures of 30 degrees C and the best activity in the 10 to 50 microg/ml concentration of the herbicide. Each bacterial strain was able to degrade more than one kind of test herbicides. After incubation for 119 days, B. cereus showed the highest activity to degrade alachlor and propachlor, and B. thuringiensis to degrade metolachlor.

Antioxidant and antibacterial properties of some cultured lichens

The lichen species namely Usnea ghattensis, Heterodermia podocarpa, Arthothelium awasthii and Parmotrema tinctorum have been cultured in vitro and were screened for their antioxidant and antibacterial potential using different assay systems. The methanol extract of lichens showed antioxidant and antibacterial activities according to the order U. ghattensis>A. awasthii>H. podocarpa>P. tinctorum. The IC(50) values for the antioxidant activities of U. ghattensis and A. awasthii are less or equivalent to that of standard antioxidants. The methanolic extracts of the mycobiont and photobiont cultures of lichenU. ghattensis and A. awasthii were effective against Bacillus licheniformis, Bacillus megaterium, Bacillus subtilis and Staphylococcus aureus. The minimum inhibitory concentration (MIC) of the extract was found between 5 and 10microg extract/ml. The results suggested that the extract of mycobiont and photobiont cultures of lichen U. ghattensis and A. awasthii could be of use as an easily accessible source of natural antioxidants and antibacterial properties for the possible food supplement or in the pharmaceutical industry.

Bacillus licheniformis proteases as high value added products from fermentation of wastewater sludge: pre-treatment of sludge to increase the performance of the process

Wastewater sludge is a complex raw material that can support growth and protease production by Bacillus licheniformis. In this study, sludge was treated by different thermo-alkaline pre-treatment methods and subjected to Bacillus licheniformis fermentation in bench scale fermentors under controlled conditions. Thermo-alkaline treatment was found to be an effective pre-treatment process in order to enhance the proteolytic activity. Among the different pre-treated sludges tested, a mixture of raw and hydrolysed sludge caused an increase of 15% in the protease activity, as compared to the untreated sludge. The benefit of hydrolysis has been attributed to a better oxygen transfer due to decrease in media viscosity and to an increase in nutrient availability. Foam formation was a major concern during fermentation with hydrolysed sludge. The studies showed that addition of a chemical anti-foaming agent (polypropylene glycol) during fermentation to control foam could negatively influence the protease production by increasing the viscosity of sludge.

Bacterial cytoskeleton: not your run-of-the-mill tubulin

Large plasmids of some Bacillus species encode a distinct tubulin homolog, TubZ, implicated in maintenance of the host plasmid. A recent study has shown that TubZ polymers exhibit treadmilling behavior in vivo, suggesting that they are involved in mitotic activity.

Antibacterial activity of a bacteriocin-like substance produced by Bacillus sp. P34 that targets the bacterial cell envelope

The objective of this study was to investigate the mode of action of BLS P34, a bacteriocin-like substance (BLS) produced by a novel Bacillus sp. strain P34 isolated from the Amazon basin. The effect of the BLS was tested against Listeria monocytogenes, showing a bactericidal effect at 200 AU (activity units) ml(-1), while no inhibition of spore outgrowth of Bacillus cereus was observed with a dose of 1,600 AU ml(-1). Growth of Escherichia coli and Salmonella Enteritidis was inhibited, but only when the chelating agent EDTA was co-added with the BLS. The effect of BLS P34 on L. monocytogenes was also investigated by Fourier transform infrared spectroscopy. Treated cells showed an important frequency increase in 1,452 and 1,397 cm(-1) and decrease in 1,217 and 1,058 cm(-1), corresponding assignments of fatty acids and phospholipids. Transmission electron microscopy showed damaged cell envelope and loss of protoplasmic material. BLS P34 was bactericidal to Gram-positive, and also showed inhibitory effect against Gram-negative bacteria. There is evidence that its mode of action corresponds to that of a membrane-active substance. The knowledge about the mode of action of this BLS is essential to determine its effective application as an antimicrobial agent.

Coupling of permeabilized microorganisms for efficient enantioselective reduction of ketone with cofactor recycling

A novel, simple and efficient cofactor recycling method for enantioselective bioreduction has been developed by the use of permeabilized cells of a reductase-containing microorganism and a glucose dehydrogenase-containing microorganism

Cloning, functional characterization, and mode of action of a novel insecticidal pore-forming toxin, sphaericolysin, produced by Bacillus sphaericus

An insecticidal protein produced by Bacillus sphaericus A3-2 was purified to elucidate its structure and mode of action. The active principle purified from the culture broth of A3-2 was a protein with a molecular mass of 53 kDa that rapidly intoxicated German cockroaches (Blattela germanica) at a dose of about 100 ng when injected. The insecticidal protein sphaericolysin possessed the undecapeptide motif of cholesterol-dependent cytolysins and had a unique N-terminal sequence. The recombinant protein expressed in Escherichia coli was equally as potent as the native protein. Sphaericolysin-induced hemolysis resulted from the protein's pore-forming action. This activity as well as the insecticidal activity was markedly reduced by a Y159A mutation. Also, coapplication of sphaericolysin with cholesterol abolished the insecticidal action, suggesting that cholesterol binding plays an important role in insecticidal activity. Sphaericolysin-lysed neurons dissociated from the thoracic ganglia of the German cockroaches. In addition, sphaericolysin's activity in ganglia was suppressed by the Y159A mutation. The sphaericolysin-induced damage to the cockroach ganglia was greater than the damage to the ganglia of common cutworms (Spodoptera litura), which accounts, at least in part, for the higher sensitivity to sphaericolysin displayed by the cockroaches than that displayed by cutworms.

Method of MeasuringBacillusanthracisSpores in the Presence of Copious Amounts ofBacillusthuringiensisandBacilluscereus

A sensitive and reliable method for the detection of Bacillus anthracis (BA; Sterne strain 7702) spores in presence of large amounts of Bacillus thuringiensis (BT) and Bacillus cereus (BC) is presented based on a novel PZT-anchored piezoelectric excited millimeter-sized cantilever (PAPEMC) sensor with a sensing area of 1.5 mm2. Antibody (anti-BA) specific to BA spores was immobilized on the sensing area and exposed to various samples of BA, BT, and BC containing the same concentration of BA at 333 spores/mL, and the concentration of BT + BC was varied in concentration ratios of (BA:BT + BC) 0:1, 1:0, 1:1, 1:10, 1:100, and 1:1000. In each case, the sensor responded with an exponential decrease in resonant frequency and the steady-state frequency changes reached were 14 +/- 31 (n = 11), 2742 +/- 38 (n = 3), 3053 +/- 19 (n = 2), 2777 +/- 26 (n = 2), 2953 +/- 24 (n = 2), and 3105 +/- 27 (n = 2) Hz, respectively, in 0, 27, 45, 63, 154, and 219 min. The bound BA spores were released in each experiment, and the sensor response was nearly identical to the frequency change during attachment. These results suggest that the transport of BA spores to the antibody immobilized surface was hindered by the presence of other Bacillus species. The observed binding rate constant, based on the Langmuir kinetic model, was determined to be 0.15 min-1. A hindrance factor (alpha) is defined to describe the reduced attachment rate in the presence of BT + BC and found to increase exponentially with BT and BC concentration. The hindrance factor increased from 3.52 at 333 BT + BC spores/mL to 11.04 at 3.33 x 105 BT + BC spores/mL, suggesting that alpha is a strong function of BT and BC concentration. The significance of these results is that anti-BA functionalized PEMC sensors are highly selective to Bacillus anthracis spores and the presence of other Bacillus species, in large amounts, does not prevent binding but impedes BA transport to the sensor.

Bacillus lehensis sp. nov., an alkalitolerant bacterium isolated from soil

A Gram-positive, endospore-forming, alkalitolerant bacterial strain, designated MLB2T, was isolated from soil from Leh, India, and was subjected to a polyphasic taxonomic study. The strain exhibited phenotypic properties that included chemotaxonomic characteristics consistent with its classification in the genusBacillus. Growth was observed at pH 7.0–11.0, but not at pH 6.0. The DNA G+C content was 41.4 mol%. The highest level of 16S rRNA gene sequence similarity was withBacillus oshimensisJCM 12663T(98.8 %). However, DNA–DNA hybridization experiments indicated low levels of genomic relatedness with the type strains ofB. oshimensis(62 %),Bacillus patagoniensis(55 %),Bacillus clausii(51 %) andBacillus gibsonii(34 %), the species with which strain MLB2Tformed a coherent cluster (based on the results of the phylogenetic analysis). On the basis of the phenotypic characteristics and genotypic distinctiveness of strain MLB2T, it should be classified within a novel species ofBacillus, for which the nameBacillus lehensissp. nov. is proposed. The type strain is MLB2T(=MTCC 7633T=JCM 13820T).

Effects of DNP on the cell surface properties of marine bacteria and its implication for adhesion to surfaces

The effect of 2, 4-dinitrophenol (DNP) on the extracelluar polysaccharides (EPS), cell surface charge, and the hydrophobicity of six marine bacterial cultures was studied, and its influence on attachment of these bacteria to glass and polystyrene was evaluated. DNP treatment did not influence cell surface charge and EPS production, but had a significant effect on hydrophobicity of both hydrophilic (p = 0.05) and hydrophobic (p = 0.01) cultures. Significant reduction in the attachment of all the six cultures to glass (p = 0.02) and polystyrene (p = 0.03) was observed after DNP treatment. Moreover, hydrophobicity but not the cell surface charge or EPS production influenced bacterial cell attachment to glass and polystyrene. From this study, it was evident that DNP treatment influenced bacterial cell surface hydrophobicity, which in turn, reduced bacterial adhesion to surfaces.

Oil biodegradation by Bacillus strains isolated from the rock of an oil reservoir located in a deep-water production basin in Brazil

Sixteen spore forming Gram-positive bacteria were isolated from the rock of an oil reservoir located in a deep-water production basin in Brazil. These strains were identified as belonging to the genus Bacillus using classical biochemical techniques and API 50CH kits, and their identity was confirmed by sequencing of part of the 16S rRNA gene. All strains were tested for oil degradation ability in microplates using Arabian Light and Marlin oils and only seven strains showed positive results in both kinds of oils. They were also able to grow in the presence of carbazole, n-hexadecane and polyalphaolefin (PAO), but not in toluene, as the only carbon sources. The production of key enzymes involved with aromatic hydrocarbons biodegradation process by Bacillus strains (catechol 1,2-dioxygenase and catechol 2,3-dioxygenase) was verified spectrophotometrically by detection of cis,cis-muconic acid and 2-hydroxymuconic semialdehyde, and results indicated that the ortho ring cleavage pathway is preferential. Furthermore, polymerase chain reaction (PCR) products were obtained when the DNA of seven Bacillus strains were screened for the presence of catabolic genes encoding alkane monooxygenase, catechol 1,2-dioxygenase, and/or catechol 2,3-dioxygenase. This is the first study on Bacillus strains isolated from an oil reservoir in Brazil.