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Microbiology Spectrum May 2019The group includes several species with closely related phylogeny. The most well-studied members of the group, , , and , are known for their pathogenic potential.... (Review)
Review
The group includes several species with closely related phylogeny. The most well-studied members of the group, , , and , are known for their pathogenic potential. Here, we present the historical rationale for speciation and discuss shared and unique features of these bacteria. Aspects of cell morphology and physiology, and genome sequence similarity and gene synteny support close evolutionary relationships for these three species. For many strains, distinct differences in virulence factor synthesis provide facile means for species assignment. is the causative agent of anthrax. Some strains are commonly recognized as food poisoning agents, but strains can also cause localized wound and eye infections as well as systemic disease. Certain strains are entomopathogens and have been commercialized for use as biopesticides, while some strains have been reported to cause infection in immunocompromised individuals. In this article we compare and contrast , , and , including ecology, cell structure and development, virulence attributes, gene regulation and genetic exchange systems, and experimental models of disease.
Topics: Animals; Anthrax; Anthrax Vaccines; Bacillus; Bacillus anthracis; Bacillus cereus; Bacillus thuringiensis; Bacterial Toxins; Bacterial Vaccines; Biological Control Agents; DNA, Bacterial; Disease Models, Animal; Ecology; Gastrointestinal Diseases; Gene Expression Regulation, Bacterial; Genes, Bacterial; Genome, Bacterial; Humans; Infections; Invertebrates; Phylogeny; Species Specificity; Spores, Bacterial; Virulence
PubMed: 31111815
DOI: 10.1128/microbiolspec.GPP3-0032-2018 -
Gastroenterology Sep 2020Alterations in the intestinal microbiota affect development of colorectal cancer and drug metabolism. We studied whether the intestinal microbiota affect the ability of...
BACKGROUND & AIMS
Alterations in the intestinal microbiota affect development of colorectal cancer and drug metabolism. We studied whether the intestinal microbiota affect the ability of aspirin to reduce colon tumor development in mice.
METHODS
We performed studies with APC mice and mice given azoxymethane and dextran sulfate sodium to induce colorectal carcinogenesis. Some mice were given antibiotics to deplete intestinal microbes, with or without aspirin, throughout the entire experiment. Germ-free mice were studied in validation experiments. Colon tissues were collected and analyzed by histopathology, quantitative reverse-transcription polymerase chain reaction, and immunoblots. Blood samples and gut luminal contents were analyzed by liquid chromatography/mass spectrometry and an arylesterase activity assay. Fecal samples were analyzed by 16S ribosomal RNA gene and shotgun metagenome sequencing.
RESULTS
Administration of aspirin to mice reduced colorectal tumor number and load in APC mice and mice given azoxymethane and dextran sulfate sodium that had been given antibiotics (depleted gut microbiota), but not in mice with intact microbiota. Germ-free mice given aspirin developed fewer colorectal tumors than conventionalized germ-free mice given aspirin. Plasma levels of aspirin were higher in mice given antibiotics than in mice with intact gut microbiota. Analyses of luminal contents revealed that aerobic gut microbes, including Lysinibacillus sphaericus, degrade aspirin. Germ-free mice fed L sphaericus had lower plasma levels of aspirin than germ-free mice that were not fed this bacterium. There was an inverse correlation between aspirin dose and colorectal tumor development in conventional mice, but this correlation was lost with increased abundance of L sphaericus. Fecal samples from mice fed aspirin were enriched in Bifidobacterium and Lactobacillus genera, which are considered beneficial, and had reductions in Alistipes finegoldii and Bacteroides fragili, which are considered pathogenic.
CONCLUSIONS
Aspirin reduces development of colorectal tumors in APC mice and mice given azoxymethane and dextran sulfate sodium, depending on the presence of intestinal microbes. L sphaericus in the gut degrades aspirin and reduced its chemopreventive effects in mice. Fecal samples from mice fed aspirin were enriched in beneficial bacteria, with reductions in pathogenic bacteria.
Topics: Adenomatous Polyposis Coli Protein; Animals; Anti-Bacterial Agents; Anticarcinogenic Agents; Aspirin; Azoxymethane; Bacillaceae; Bacteroides fragilis; Bacteroidetes; Biological Availability; Carcinogenesis; Colitis; Colon; Colorectal Neoplasms; DNA, Bacterial; Dextran Sulfate; Disease Models, Animal; Dose-Response Relationship, Drug; Feces; Gastrointestinal Microbiome; Germ-Free Life; Humans; Intestinal Mucosa; Male; Mice; Mice, Transgenic; RNA, Ribosomal, 16S
PubMed: 32387495
DOI: 10.1053/j.gastro.2020.05.004 -
Toxins May 2019Toxin-antitoxin (TA) systems were originally discovered as plasmid maintenance systems in a multitude of free-living bacteria, but were afterwards found to also be... (Review)
Review
Toxin-antitoxin (TA) systems were originally discovered as plasmid maintenance systems in a multitude of free-living bacteria, but were afterwards found to also be widespread in bacterial chromosomes. TA loci comprise two genes, one coding for a stable toxin whose overexpression kills the cell or causes growth stasis, and the other coding for an unstable antitoxin that counteracts toxin action. Of the currently known six types of TA systems, in , so far only type I and type II TA systems were found, all encoded on the chromosome. Here, we review our present knowledge of these systems, the mechanisms of antitoxin and toxin action, and the regulation of their expression, and we discuss their evolution and possible physiological role.
Topics: Bacillus subtilis; Toxin-Antitoxin Systems
PubMed: 31075979
DOI: 10.3390/toxins11050262 -
Microbiology Spectrum Apr 2015Members of the family Bacillaceae are among the most robust bacteria on Earth, which is mainly due to their ability to form resistant endospores. This trait is believed... (Review)
Review
Members of the family Bacillaceae are among the most robust bacteria on Earth, which is mainly due to their ability to form resistant endospores. This trait is believed to be the key factor determining the ecology of these bacteria. However, they also perform fundamental roles in soil ecology (i.e., the cycling of organic matter) and in plant health and growth stimulation (e.g., via suppression of plant pathogens and phosphate solubilization). In this review, we describe the high functional and genetic diversity that is found within the Bacillaceae (a family of low-G+C% Gram-positive spore-forming bacteria), their roles in ecology and in applied sciences related to agriculture. We then pose questions with respect to their ecological behavior, zooming in on the intricate social behavior that is becoming increasingly well characterized for some members of Bacillaceae. Such social behavior, which includes cell-to-cell signaling via quorum sensing or other mechanisms (e.g., the production of extracellular hydrolytic enzymes, toxins, antibiotics and/or surfactants) is a key determinant of their lifestyle and is also believed to drive diversification processes. It is only with a deeper understanding of cell-to-cell interactions that we will be able to understand the ecological and diversification processes of natural populations within the family Bacillaceae. Ultimately, the resulting improvements in understanding will benefit practical efforts to apply representatives of these bacteria in promoting plant growth as well as biological control of plant pathogens.
Topics: Animals; Bacillaceae; Ecosystem; Genetic Variation; Humans; Microbial Interactions; Plants
PubMed: 26104706
DOI: 10.1128/microbiolspec.TBS-0017-2013 -
Biomolecules Jul 2022Thrombosis has threatened human health in past decades. nattokinase is a potential low-cost thrombolytic drug without side-effects and has been introduced into the... (Review)
Review
Thrombosis has threatened human health in past decades. nattokinase is a potential low-cost thrombolytic drug without side-effects and has been introduced into the consumer market as a functional food or dietary supplement. This review firstly summarizes the biodiversity of sources and the fermentation process of nattokinase, and systematically elucidates the structure, catalytic mechanism and enzymatic properties of nattokinase. In view of the problems of low fermentation yield, insufficient activity and stability of nattokinase, this review discusses the heterologous expression of nattokinase in different microbial hosts and summarizes the protein and genetic engineering progress of nattokinase-producing strains. Finally, this review summarizes the clinical applications of nattokinase.
Topics: Bacillus; Bacillus subtilis; Bioengineering; Biotechnology; Humans; Subtilisins
PubMed: 35883536
DOI: 10.3390/biom12070980 -
Microbiology Spectrum Oct 2014The family Bacillaceae constitutes a phenotypically diverse and globally ubiquitous assemblage of bacteria. Investigation into how evolution has shaped, and continues to... (Review)
Review
The family Bacillaceae constitutes a phenotypically diverse and globally ubiquitous assemblage of bacteria. Investigation into how evolution has shaped, and continues to shape, this family has relied on several widely ranging approaches from classical taxonomy, ecological field studies, and evolution in soil microcosms to genomic-scale phylogenetics, laboratory, and directed evolution experiments. One unifying characteristic of the Bacillaceae, the endospore, poses unique challenges to answering questions regarding both the calculation of evolutionary rates and claims of extreme longevity in ancient environmental samples.
Topics: Bacillaceae; Environmental Microbiology; Evolution, Molecular; Phylogeny
PubMed: 26104365
DOI: 10.1128/microbiolspec.TBS-0020-2014 -
Journal of Applied Microbiology Jan 2022Bacillus cytotoxicus is a member of the Bacillus cereus group with the ability to grow at high temperatures (up to 52℃) and to synthesize cytotoxin K-1, a... (Review)
Review
Bacillus cytotoxicus is a member of the Bacillus cereus group with the ability to grow at high temperatures (up to 52℃) and to synthesize cytotoxin K-1, a diarrhoeagenic cytotoxin, which appears to be unique to this species and more cytotoxic than the cytotoxin K-2 produced by other members of this group. Only a few isolates of this species have been characterized with regard to their cytotoxic effects, and the role of cytotoxin K-1 as a causative agent of food poisoning remains largely unclear. Bacillus cytotoxicus was initially isolated from a food-borne outbreak, which led to three deaths, and the organism has since been linked to other outbreaks all involving plant-based food matrices. Other studies, as well as food-borne incidents reported to the UK Food Standards Agency, detected B. cytotoxicus in insect-related products and in dried food products. With insect-related food becoming increasingly popular, the association with this pathogen is concerning, requiring further investigation and evidence to protect public health. This review summarizes the current knowledge around B. cytotoxicus and highlights gaps in the literature from a food safety perspective.
Topics: Bacillus; Bacillus cereus; Enterotoxins; Food Microbiology; Food Safety; Foodborne Diseases; Humans
PubMed: 34260791
DOI: 10.1111/jam.15214 -
Transcription Aug 2021The low G + C Gram-positive bacteria represent some of the most medically and industrially important microorganisms. They are relied on for the production of food and... (Review)
Review
The low G + C Gram-positive bacteria represent some of the most medically and industrially important microorganisms. They are relied on for the production of food and dietary supplements, enzymes and antibiotics, as well as being responsible for the majority of nosocomial infections and serving as a reservoir for antibiotic resistance. Control of gene expression in this group is more highly studied than in any bacteria other than the Gram-negative model Escherichia coli, yet until recently no structural information on RNA polymerase (RNAP) from this group was available. This review will summarize recent reports on the high-resolution structure of RNAP from the model low G + C representative Bacillus subtilis, including the role of auxiliary subunits and , and outline approaches for the development of antimicrobials to target RNAP from this group.
Topics: Bacillus subtilis; Bacterial Proteins; DNA-Directed RNA Polymerases; Gram-Positive Bacteria; Transcription, Genetic
PubMed: 34403307
DOI: 10.1080/21541264.2021.1964328 -
Applied Microbiology and Biotechnology Jun 2023The aim of the present study was the characterisation of three true subtilisins and one phylogenetically intermediate subtilisin from halotolerant and halophilic...
The aim of the present study was the characterisation of three true subtilisins and one phylogenetically intermediate subtilisin from halotolerant and halophilic microorganisms. Considering the currently growing enzyme market for efficient and novel biocatalysts, data mining is a promising source for novel, as yet uncharacterised enzymes, especially from halophilic or halotolerant Bacillaceae, which offer great potential to meet industrial needs. Both halophilic bacteria Pontibacillus marinus DSM 16465 and Alkalibacillus haloalkaliphilus DSM 5271 and both halotolerant bacteria Metabacillus indicus DSM 16189 and Litchfieldia alkalitelluris DSM 16976 served as a source for the four new subtilisins SPPM, SPAH, SPMI and SPLA. The protease genes were cloned and expressed in Bacillus subtilis DB104. Purification to apparent homogeneity was achieved by ethanol precipitation, desalting and ion-exchange chromatography. Enzyme activity could be observed between pH 5.0-12.0 with an optimum for SPPM, SPMI and SPLA around pH 9.0 and for SPAH at pH 10.0. The optimal temperature for SPMI and SPLA was 70 °C and for SPPM and SPAH 55 °C and 50 °C, respectively. All proteases showed high stability towards 5% (w/v) SDS and were active even at NaCl concentrations of 5 M. The four proteases demonstrate potential for future biotechnological applications. KEY POINTS: • Halophilic and halotolerant Bacillaceae are a valuable source of new subtilisins. • Four new subtilisins were biochemically characterised in detail. • The four proteases show potential for future biotechnological applications.
Topics: Bacillaceae; Bacteria; Subtilisin; Peptide Hydrolases; Temperature
PubMed: 37160606
DOI: 10.1007/s00253-023-12553-w -
Microbiology (Reading, England) May 2021is recognized as a causative agent of gastrointestinal syndromes, but can also cause a devastating form of intraocular infection known as endophthalmitis. We have...
is recognized as a causative agent of gastrointestinal syndromes, but can also cause a devastating form of intraocular infection known as endophthalmitis. We have previously reported that the PlcR/PapR master virulence factor regulator system regulates intraocular virulence, and that the S-layer protein (SlpA) contributes to the severity of endophthalmitis. To better understand the role of other virulence genes in endophthalmitis, expression of a subset of factors was measured at the midpoint of disease progression in a murine model of endophthalmitis by RNA-Seq. Several cytolytic toxins were expressed at significantly higher levels than in BHI. The virulence regulators , , and were also expressed . However, at this timepoint, / was not detectable, although we previously reported that a mutant deficient in PlcR was attenuated in the eye. The motility-related genes , , and , and the chemotaxis-related gene were detected during infection. We have shown previously that motility and chemotaxis phenotypes are important in endophthalmitis. The variant of manganese superoxide dismutase was the most highly expressed gene . Expression of the surface layer protein gene, , an activator of Toll-like receptors (TLR)-2 and -4, was also detected during infection, albeit at low levels. Genes expressed in a mouse model of endophthalmitis might play crucial roles in the unique virulence of endophthalmitis, and serve as candidates for novel therapies designed to attenuate the severity of this often blinding infection.
Topics: Animals; Bacillus cereus; Bacterial Proteins; Endophthalmitis; Female; Gene Expression Regulation, Bacterial; Humans; Male; Mice; Mice, Inbred C57BL; Virulence
PubMed: 34032564
DOI: 10.1099/mic.0.001057