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Biological Chemistry Nov 2020
Topics: Bacillus subtilis; Escherichia coli; Humans
PubMed: 32918804
DOI: 10.1515/hsz-2020-0229 -
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 -
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 -
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 -
Nature Communications Apr 2020Bacteria can produce membranous nanotubes that mediate contact-dependent exchange of molecules among bacterial cells. However, it is unclear how nanotubes cross the cell...
Bacteria can produce membranous nanotubes that mediate contact-dependent exchange of molecules among bacterial cells. However, it is unclear how nanotubes cross the cell wall to emerge from the donor or to penetrate into the recipient cell. Here, we report that Bacillus subtilis utilizes cell wall remodeling enzymes, the LytC amidase and its enhancer LytB, for efficient nanotube extrusion and penetration. Nanotube production is reduced in a lytBC mutant, and the few nanotubes formed appear deficient in penetrating into target cells. Donor-derived LytB molecules localize along nanotubes and on the surface of nanotube-connected neighbouring cells, primarily at sites of nanotube penetration. Furthermore, LytB from donor B. subtilis can activate LytC of recipient bacteria from diverse species, facilitating cell wall hydrolysis to establish nanotube connection. Our data provide a mechanistic view of how intercellular connecting devices can be formed among neighbouring bacteria.
Topics: Amidohydrolases; Bacillus subtilis; Bacterial Proteins; Cell Surface Extensions; Cell Wall; Conjugation, Genetic; Protein Transport
PubMed: 32321911
DOI: 10.1038/s41467-020-15605-1 -
Nature Microbiology Nov 2022The transcriptome-wide contributions of Rho-dependent and intrinsic (Rho-independent) transcription termination mechanisms in bacteria are unclear. By sequencing...
The transcriptome-wide contributions of Rho-dependent and intrinsic (Rho-independent) transcription termination mechanisms in bacteria are unclear. By sequencing released transcripts in a wild-type strain and strains containing deficiencies in NusA, NusG and/or Rho (10 strains), we produced an atlas of terminators for the model Gram-positive bacterium Bacillus subtilis. We found that NusA and NusG stimulate 77% and 19% of all intrinsic terminators, respectively, and that both proteins participate in Rho-dependent termination. We also show that Rho stimulates termination at 10% of the intrinsic terminators in vivo. We recapitulated Rho-stimulated intrinsic termination at 5 terminators in vitro and found that Rho requires the KOW domain of NusG to stimulate this process at one of these terminators. Computational analyses of our atlas using RNAstructure, MEME suite and DiffLogo, combined with in vitro transcription experiments, revealed that Rho stimulates intrinsic terminators with weak hairpins and/or U-rich tracts by remodelling the RNA upstream of the intrinsic terminator to prevent the formation of RNA structures that could otherwise compete with the terminator hairpin. We also identified 56 putative examples of 'hybrid Rho-dependent termination', wherein classical Rho-dependent termination occurs after readthrough of a Rho-stimulated intrinsic terminator.
Topics: Bacillus subtilis; Transcription, Genetic; RNA
PubMed: 36192538
DOI: 10.1038/s41564-022-01240-7 -
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 -
Applied and Environmental Microbiology Feb 2023The genus has been widely applied in contemporary agriculture as an environmentally-friendly biological agent. However, the real effect of commercial -based fertilizers... (Review)
Review
The genus has been widely applied in contemporary agriculture as an environmentally-friendly biological agent. However, the real effect of commercial -based fertilizers and pesticides varies immensely in the field. To harness for efficient wheat production, we reviewed the diversity, functionality, and applicability of wheat-associated native for the first time. Our main findings are: (i) spp. inhabit the rhizosphere, root, stem, leaf, and kernel of wheat; (ii) B. subtilis and B. velezensis are the most widely endophytic species that can be isolated from both below and aboveground tissues; (iii) major functions of these representative strains are promotion of plant growth and alleviation of both abiotic and biotic stresses in wheat; (iv) stability and effectiveness are 2 major challenges during field application; (v) a STVAE pipeline that includes 5 processes, namely, Screen, Test, Validation, Application, and Evaluation, has been proposed for the capture and refinement of wheat-associated spp. In particular, this review comprehensively addresses possible solutions, concerns, and criteria during the development of native -based inoculants for sustainable wheat production.
Topics: Bacillus; Triticum; Agriculture; Plant Development
PubMed: 36695599
DOI: 10.1128/aem.01247-22 -
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