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International Microbiology : the... Mar 2013To further our understanding of the virulence potential of Bacillus megaterium strains, cell association and invasion assays were conducted in vitro by infecting human...
To further our understanding of the virulence potential of Bacillus megaterium strains, cell association and invasion assays were conducted in vitro by infecting human enterocytes (Caco-2 cells) with 53 strains of this bacterium isolated from honey. Two series of experiments were performed: (i) necrosis and cell detachment assays with the supernatants of bacterial culture filtrates from 16-h cultures and (ii) adhesion/invasion assays in which cultured enterocytes incubated with bacteria from 3-h cultures were resuspended in Dulbecco's modified Eagle's medium and chloramphenicol. The detachment of Caco-2 cells was evaluated by staining the cells with crystal violet. Necrosis was assessed by fluorescence microscopy of cells labeled with propidium iodide. Association (adhesion plus invasion) was determined by plate counts and invasion in an aminoglycoside protection assay. The results showed that spent culture supernatants detached and necrotized Caco-2 cells in a strain-dependent manner. Seven out of 53 B. megaterium filtered culture supernatants caused complete cell detachment. Suspensions of these same bacterial strains adhered and invaded enterocytes in 2-h infection experiments. To our knowledge, this is the first report on the interaction between B. megaterium and intestinal epithelial Caco-2 cells.
Topics: Bacillus megaterium; Bacterial Adhesion; Caco-2 Cells; Enterocytes; Honey; Host-Pathogen Interactions; Humans; Necrosis; Species Specificity; Virulence
PubMed: 24151779
DOI: 10.2436/20.1501.01.177 -
Scientific Reports Aug 2019Endogenous reactive oxygen species (ROS) are by-products of the aerobic metabolism of cells and have an important signalling role as secondary messengers in various...
Endogenous reactive oxygen species (ROS) are by-products of the aerobic metabolism of cells and have an important signalling role as secondary messengers in various physiological processes, including cell growth and development. However, the excessive production of ROS, as well as the exposure to exogenous ROS, can cause protein oxidation, lipid peroxidation and DNA damages leading to cell injuries. ROS accumulation has been associated to the development of health disorders such as neurodegenerative and cardiovascular diseases, inflammatory bowel disease and cancer. We report that spores of strain SF185, a human isolate of Bacillus megaterium, have antioxidant activity on Caco-2 cells exposed to hydrogen peroxide and on a murine model of dextran sodium sulfate-induced oxidative stress. In both model systems spores exert a protective state due to their scavenging action: on cells, spores reduce the amount of intracellular ROS, while in vivo the pre-treatment with spores protects mice from the chemically-induced damages. Overall, our results suggest that treatment with SF185 spores prevents or reduces the damages caused by oxidative stress. The human origin of SF185, its strong antioxidant activity, and its protective effects led to propose the spore of this strain as a new probiotic for gut health.
Topics: Animals; Bacillus megaterium; Caco-2 Cells; DNA Damage; Dextran Sulfate; Humans; Hydrogen Peroxide; Lipid Peroxidation; Mice; Oxidation-Reduction; Oxidative Stress; Reactive Oxygen Species; Spores, Bacterial
PubMed: 31427655
DOI: 10.1038/s41598-019-48531-4 -
BMC Biotechnology Jul 2022Unlike most other P450 cytochrome monooxygenases, CYP102A1 from Bacillus megaterium (BM3) is both soluble and fused to its redox partner forming a single polypeptide...
BACKGROUND
Unlike most other P450 cytochrome monooxygenases, CYP102A1 from Bacillus megaterium (BM3) is both soluble and fused to its redox partner forming a single polypeptide chain. Like other monooxygenases, it can catalyze the insertion of oxygen unto the carbon-hydrogen bond which can result in a wide variety of commercially relevant products for pharmaceutical and fine chemical industries. However, the instability of the enzyme holds back the implementation of a BM3-based biocatalytic industrial processes due to the important enzyme cost it would prompt.
RESULTS
In this work, we sought to enhance BM3's total specific product output by using experimental evolution, an approach not yet reported to improve this enzyme. By exploiting B. megaterium's own oleic acid metabolism, we pressed the evolution of a new variant of BM3, harbouring 34 new amino acid substitutions. The resulting variant, dubbed DE, increased the conversion of the substrate 10-pNCA to its product p-nitrophenolate 1.23 and 1.76-fold when using respectively NADPH or NADH as a cofactor, compared to wild type BM3.
CONCLUSIONS
This new DE variant, showed increased organic cosolvent tolerance, increased product output and increased versatility in the use of either nicotinamide cofactors NADPH and NADH. Experimental evolution can be used to evolve or to create libraries of evolved BM3 variants with increased productivity and cosolvent tolerance. Such libraries could in turn be used in bioinformatics to further evolve BM3 more precisely. The experimental evolution results also supports the hypothesis which surmises that one of the roles of BM3 in Bacillus megaterium is to protect it from exogenous unsaturated fatty acids by breaking them down.
Topics: Bacillus megaterium; Bacterial Proteins; Cytochrome P-450 Enzyme System; NAD; NADP; NADPH-Ferrihemoprotein Reductase; Oleic Acid; Oxidation-Reduction
PubMed: 35831844
DOI: 10.1186/s12896-022-00750-w -
Molecules (Basel, Switzerland) Jul 2023Wild-type cytochrome P450 CYP102A1 from is a highly efficient monooxygenase for the oxidation of long-chain fatty acids. The unique features of CYP102A1, such as high... (Review)
Review
Wild-type cytochrome P450 CYP102A1 from is a highly efficient monooxygenase for the oxidation of long-chain fatty acids. The unique features of CYP102A1, such as high catalytic activity, expression yield, regio- and stereoselectivity, and self-sufficiency in electron transfer as a fusion protein, afford the requirements for an ideal biocatalyst. In the past three decades, remarkable progress has been made in engineering CYP102A1 for applications in drug discovery, biosynthesis, and biotechnology. The repertoire of engineered CYP102A1 variants has grown tremendously, whereas the substrate repertoire is avalanched to encompass alkanes, alkenes, aromatics, organic solvents, pharmaceuticals, drugs, and many more. In this article, we highlight the major advances in the past five years in our understanding of the structure and function of CYP102A1 and the methodologies used to engineer CYP102A1 for novel applications. The objective is to provide a succinct review of the latest developments with reference to the body of CYP102A1-related literature.
Topics: NADPH-Ferrihemoprotein Reductase; Cytochrome P-450 Enzyme System; Oxidation-Reduction; Electron Transport; Bacterial Proteins; Bacillus megaterium
PubMed: 37513226
DOI: 10.3390/molecules28145353 -
Applied and Environmental Microbiology Nov 2003Bacillus megaterium QM B1551 plasmid pBM400, one of seven indigenous plasmids, has been labeled with a selectable marker, isolated, completely sequenced, and partially...
Bacillus megaterium QM B1551 plasmid pBM400, one of seven indigenous plasmids, has been labeled with a selectable marker, isolated, completely sequenced, and partially characterized. A sequence of 53,903 bp was generated, revealing a total of 50 predicted open reading frames (ORFs); 33 were carried on one strand and 17 were carried on the other. These ORFs comprised 57% of the pBM400 sequence. Besides the replicon region and a complete rRNA operon that have previously been described, several interesting genes were found, including genes for predicted proteins for cell division (FtsZ and FtsK), DNA-RNA interaction (FtsK, Int/Rec, and reverse transcriptase), germination (CwlJ), styrene degradation (StyA), and heavy metal resistance (Cu-Cd export and ATPase). Three of the ORF products had high similarities to proteins from the Bacillus anthracis virulence plasmid pXO1. An insertion element with similarity to the IS256 family and several hypothetical proteins similar to those from the chromosomes of other Bacillus and Lactococcus species were present. This study provides a basis for isolation and sequencing of other high-molecular-weight plasmids from QM B1551 and for understanding the role of megaplasmids in gram-positive bacteria. The genes carried by pBM400 suggest a possible role of this plasmid in the survival of B. megaterium in hostile environments with heavy metals or styrene and also suggest that there has been an exchange of genes within the gram-positive bacteria, including pathogens.
Topics: Bacillus megaterium; Bacterial Proteins; DNA Transposable Elements; Molecular Sequence Data; Open Reading Frames; Plasmids; Recombination, Genetic; Sequence Analysis, DNA; Virulence
PubMed: 14602653
DOI: 10.1128/AEM.69.11.6888-6898.2003 -
Journal of Applied Microbiology Oct 2007Cloning and expression of keratinase gene in Bacillus megaterium and optimization of fermentation conditions for the production of keratinase by recombinant strain.
AIMS
Cloning and expression of keratinase gene in Bacillus megaterium and optimization of fermentation conditions for the production of keratinase by recombinant strain.
METHODS AND RESULTS
The keratinase gene with and without leader sequence from the chromosomal DNA of Bacillus licheniformis MKU3 was amplified by PCR and cloned into pET30b and transferred into Escherichia coli BL21. The ker gene without leader sequence only expressed in E. coli and the recombinant strain produced an intracellular keratinase activity of 74.3 U ml(-1). The ker gene was further subcloned into E. coli-Bacillus shuttle vector, pWH1520. Bacillus megaterium ATCC 14945 carrying the recombinant plasmid pWHK3 expressed the ker gene placed under xylA promoter and produced an extracellular keratinase activity of 95 U ml(-1). Response surface methodology (RSM) was employed to optimize the fermentation condition and to improve the level of keratinase production by the recombinant strain. A maximum keratinolytic activity of 166.2 U ml(-1) (specific activity, 33.25 U mg(-1)) was obtained in 18 h of the fermentation carried out with an initial inoculum of 0.4 OD600 nm and xylose concentration of 0.75% w/v.
CONCLUSIONS
Bacillus licheniformis keratinase was cloned and successfully expressed using T7 promoter in E. coli and xylose inducible expression system in B. megaterium. Response surface methodology was employed to optimize the process parameters, which resulted in a three-fold higher level of keratinase production by the recombinant B. megaterium (pWHK3) than the wild type strain B. licheniformis MKU3.
SIGNIFICANCE AND IMPACT OF THE STUDY
This study suggests that B. megaterium is a suitable host for the expression of cloned genes from heterologous origin. Optimization of fermentation conditions improved the keratinase production by B. megaterium (pWHK3) and suggested that this recombinant strain could be used for the production of keratinase.
Topics: Bacillus megaterium; Cloning, Molecular; DNA, Bacterial; Electrophoresis, Polyacrylamide Gel; Escherichia coli; Fermentation; Gene Expression Regulation, Bacterial; Gene Expression Regulation, Enzymologic; Molecular Sequence Data; Peptide Hydrolases; Recombinant Proteins
PubMed: 17897234
DOI: 10.1111/j.1365-2672.2007.03372.x -
PloS One 2018The intense use of herbicides for weed control in agriculture causes selection pressure on soil microbiota and water ecosystems, possibly resulting in changes to...
The intense use of herbicides for weed control in agriculture causes selection pressure on soil microbiota and water ecosystems, possibly resulting in changes to microbial processes, such as biogeochemical cycles. These xenobiotics may increase the production of reactive oxygen species and consequently affect the survival of microorganisms, which need to develop strategies to adapt to these conditions and maintain their ecological functionality. This study analyzed the adaptive responses of bacterial isolates belonging to the same species, originating from two different environments (water and soil), and subjected to selection pressure by herbicides. The effects of herbicide Callisto and its active ingredient, mesotrione, induced different adaptation strategies on the cellular, enzymatic, and structural systems of two Bacillus megaterium isolates obtained from these environments. The lipid saturation patterns observed may have affected membrane permeability in response to this herbicide. Moreover, this may have led to different levels of responses involving superoxide dismutase and catalase activities, and enzyme polymorphisms. Due to these response systems, the strain isolated from water exhibited higher growth rates than did the soil strain, in evaluations made in oligotrophic culture media, which would be more like that found in semi-pristine aquatic environments. The influence of the intracellular oxidizing environments, which changed the mode of degradation of mesotrione in our experimental model and produced different metabolites, can also be observed in soil and water at sites related to agriculture. Since the different metabolites may present different levels of toxicity, we suggest that this fact should be considered in studies on the fate of agrochemicals in different environments.
Topics: Adaptation, Physiological; Bacillus megaterium; Biodegradation, Environmental; Cyclohexanones; Ecosystem; Herbicides; Lipid Peroxidation; Microbial Viability; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Soil Microbiology; Water Microbiology
PubMed: 29694403
DOI: 10.1371/journal.pone.0196166 -
Journal of Bacteriology Aug 2011Bacillus megaterium is deep-rooted in the Bacillus phylogeny, making it an evolutionarily key species and of particular importance in understanding genome evolution,...
Bacillus megaterium is deep-rooted in the Bacillus phylogeny, making it an evolutionarily key species and of particular importance in understanding genome evolution, dynamics, and plasticity in the bacilli. B. megaterium is a commercially available, nonpathogenic host for the biotechnological production of several substances, including vitamin B(12), penicillin acylase, and amylases. Here, we report the analysis of the first complete genome sequences of two important B. megaterium strains, the plasmidless strain DSM319 and QM B1551, which harbors seven indigenous plasmids. The 5.1-Mbp chromosome carries approximately 5,300 genes, while QM B1551 plasmids represent a combined 417 kb and 523 genes, one of the largest plasmid arrays sequenced in a single bacterial strain. We have documented extensive gene transfer between the plasmids and the chromosome. Each strain carries roughly 300 strain-specific chromosomal genes that account for differences in their experimentally confirmed phenotypes. B. megaterium is able to synthesize vitamin B(12) through an oxygen-independent adenosylcobalamin pathway, which together with other key energetic and metabolic pathways has now been fully reconstructed. Other novel genes include a second ftsZ gene, which may be responsible for the large cell size of members of this species, as well as genes for gas vesicles, a second β-galactosidase gene, and most but not all of the genes needed for genetic competence. Comprehensive analyses of the global Bacillus gene pool showed that only an asymmetric region around the origin of replication was syntenic across the genus. This appears to be a characteristic feature of the Bacillus spp. genome architecture and may be key to their sporulating lifestyle.
Topics: Bacillus megaterium; Chromosomes, Bacterial; Flagella; Gene Expression Regulation, Bacterial; Genetic Variation; Genome, Bacterial; Molecular Sequence Data; Phylogeny; Plasmids; Species Specificity
PubMed: 21705586
DOI: 10.1128/JB.00449-11 -
Annals of Botany Jul 2017Plant growth-promoting bacteria (PGPB) are soil micro-organisms able to interact with plants and stimulate their growth, positively affecting plant physiology and...
BACKGROUND AND AIMS
Plant growth-promoting bacteria (PGPB) are soil micro-organisms able to interact with plants and stimulate their growth, positively affecting plant physiology and development. Although ethylene plays a key role in plant growth, little is known about the involvement of ethylene sensitivity in bacterial inoculation effects on plant physiology. Thus, the present study was pursued to establish whether ethylene perception is critical for plant-bacteria interaction and growth induction by two different PGPB strains, and to assess the physiological effects of these strains in juvenile and mature tomato ( Solanum lycopersicum ) plants.
METHODS
An experiment was performed with the ethylene-insensitive tomato never ripe and its isogenic wild-type line in which these two strains were inoculated with either Bacillus megaterium or Enterobacter sp. C7. Plants were grown until juvenile and mature stages, when biomass, stomatal conductance, photosynthesis as well as nutritional, hormonal and metabolic statuses were analysed.
KEY RESULTS
Bacillus megaterium promoted growth only in mature wild type plants. However, Enterobacter C7 PGPB activity affected both wild-type and never ripe plants. Furthermore, PGPB inoculation affected physiological parameters and root metabolite levels in juvenile plants; meanwhile plant nutrition was highly dependent on ethylene sensitivity and was altered at the mature stage. Bacillus megaterium inoculation improved carbon assimilation in wild-type plants. However, insensitivity to ethylene compromised B. megaterium PGPB activity, affecting photosynthetic efficiency, plant nutrition and the root sugar content. Nevertheless, Enterobacter C7 inoculation modified the root amino acid content in addition to stomatal conductance and plant nutrition.
CONCLUSIONS
Insensitivity to ethylene severely impaired B. megaterium interaction with tomato plants, resulting in physiological modifications and loss of PGPB activity. In contrast, Enterobacter C7 inoculation stimulated growth independently of ethylene perception and improved nitrogen assimilation in ethylene-insensitive plants. Thus, ethylene sensitivity is a determinant for B. megaterium , but is not involved in Enterobacter C7 PGPB activity.
Topics: Bacillus megaterium; Enterobacter; Ethylenes; Solanum lycopersicum; Plant Roots
PubMed: 28586422
DOI: 10.1093/aob/mcx052 -
Microbial Cell Factories Aug 2019Heparosan is the unsulfated precursor of heparin and heparan sulfate and its synthesis is typically the first step in the production of bioengineered heparin. In...
BACKGROUND
Heparosan is the unsulfated precursor of heparin and heparan sulfate and its synthesis is typically the first step in the production of bioengineered heparin. In addition to its utility as the starting material for this important anticoagulant and anti-inflammatory drug, heparosan is a versatile compound that possesses suitable chemical and physical properties for making a variety of high-quality tissue engineering biomaterials, gels and scaffolds, as well as serving as a drug delivery vehicle. The selected production host was the Gram-positive bacterium Bacillus megaterium, which represents an increasingly used choice for high-yield production of intra- and extracellular biomolecules for scientific and industrial applications.
RESULTS
We have engineered the metabolism of B. megaterium to produce heparosan, using a T7 RNA polymerase (T7 RNAP) expression system. This system, which allows tightly regulated and efficient induction of genes of interest, has been co-opted for control of Pasteurella multocida heparosan synthase (PmHS2). Specifically, we show that B. megaterium MS941 cells co-transformed with pT7-RNAP and pPT7_PmHS2 plasmids are capable of producing heparosan upon induction with xylose, providing an alternate, safe source of heparosan. Productivities of ~ 250 mg/L of heparosan in shake flasks and ~ 2.74 g/L in fed-batch cultivation were reached. The polydisperse Pasteurella heparosan synthase products from B. megaterium primarily consisted of a relatively high molecular weight (MW) heparosan (~ 200-300 kD) that may be appropriate for producing certain biomaterials; while the less abundant lower MW heparosan fractions (~ 10-40 kD) can be a suitable starting material for heparin synthesis.
CONCLUSION
We have successfully engineered an asporogenic and non-pathogenic B. megaterium host strain to produce heparosan for various applications, through a combination of genetic manipulation and growth optimization strategies. The heparosan products from B. megaterium display a different range of MW products than traditional E. coli K5 products, diversifying its potential applications and facilitating increased product utility.
Topics: Bacillus megaterium; Bacterial Proteins; Biosynthetic Pathways; DNA-Directed RNA Polymerases; Disaccharides; Genetic Engineering; Glycosyltransferases; Metabolic Engineering; Pasteurella multocida; Viral Proteins
PubMed: 31405374
DOI: 10.1186/s12934-019-1187-9