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1.
J Agric Food Chem ; 68(4): 1101-1109, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31904947

RESUMO

ε-Poly-l-lysine (ε-PL) consists of 25-35 lysine residues which are linked by an isopeptide bond formed by dehydration condensation of α-carboxyl and ε-amino groups and has good antibacterial activity and broad-spectrum inhibition range. However, there is no clear conclusion about the structure and antibacterial mechanism of ε-PL in aqueous solution. Herein, a high purity of ε-PL was prepared using Amberlite IRC-50 ion-exchange resin. Membrane filtration and dynamic light scattering were used to study the variations of ε-PL aggregation in aqueous solution with pH value. The conformational changes and antibacterial activities of ε-PL and carbamoylated ε-PL in different water environments were studied with circular dichroism (CD) and inhibition zone. The structural changes during the spray-drying process were determined by Fourier transform infrared spectroscopy. The results indicated that the side chain amino charge played a decisive role in the ε-PL conformation and aggregation. ε-PL exhibited the properties of a ß-sheet during spray drying from acidic liquids to solids. The cation enhanced the antibacterial activity of ε-PL but did not play a key role. Instead, the backbone of ε-PL might determine the mechanism of ε-PL antibacterial.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Polilisina/química , Polilisina/farmacologia , Antibacterianos/metabolismo , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/crescimento & desenvolvimento , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Transição de Fase , Polilisina/metabolismo , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Streptomyces/química , Streptomyces/metabolismo
2.
Carbohydr Polym ; 227: 115348, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31590881

RESUMO

Ecofriendly chitosan-gelatin (Ch-ge) bio-composite films containing Quercetin-starch (Q) were synthesized using solution casting method. Physicochemical characteristics and mechanical properties of the resulting chitosan-gelatin containing Quercetin-starch films (Ch-ge-Q) were studied using UV, FTIR, XRD and SEM techniques. The films were also investigated for their swelling, water-vapor permeability (WVP), water solubility properties. The FTIR spectra confirmed the chemical interactions between the chitosan-gelatin and Q. Surface morphology of prepared film was analyzed by the SEM imaging while XRD spectra suggest the expanded crystallinity of the film with the addition of Q. The film also showed enhanced barrier property against UV rays. The reduction of water-vapor permeability and increase in tensile strength while a decrease in elongation at break has been observed in the Ch-ge-Q film compared to Ch-ge film. The antibacterial activity of Ch-ge-Q film against both gram positive (B. substilis) and gram negative (E. coli) bacteria suggested the Q loaded Ch-ge films as more feasible antibacterial candidate especially against the strain E. coli. The antioxidant activity of the Ch-ge-Q film was evaluated using the DPPH and ABTS as standards and corresponded to 81.45% of DPPH and 72.2% of ABTS scavenging activities. It was observed that the film containing Quercetin-starch presented superior antioxidant activity results in comparison to Ch-ge film promising its application in food packaging.


Assuntos
Antibacterianos/química , Antioxidantes/química , Quitosana/química , Embalagem de Alimentos , Gelatina/química , Quercetina/química , Bacillus subtilis/crescimento & desenvolvimento , Benzotiazóis/química , Compostos de Bifenilo/química , Escherichia coli/crescimento & desenvolvimento , Oxigênio/química , Permeabilidade , Picratos/química , Ácidos Sulfônicos/química , Raios Ultravioleta , Água/química
3.
Carbohydr Polym ; 227: 115367, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31590884

RESUMO

In this study, functionalized hydrogel bioadsorbents were produced from gum tragacanth (GT) carbohydrate and quaternary ammonium salt (TMSQA) as a crosslinker. The prepared bioadsorbents were used for the removal of NO3- ions from water through the electrostatic and ion exchange mechanism and antibacterial activity. The effect of quaternary ammonium content on the adsorption capacity was studied. The bioadsorbents were characterized by using FE-SEM, energy dispersive X-Ray (EDX), FT-IR, and TGA techniques. The equilibrium time and the most effective pH value for maximum NO3- removal (20 mg g-1) were 21 min and 7, respectively. A series of isotherms and kinetics models were undertaken and the obtained data were fitted well to the Langmuir isotherm and pseudo-second-order rate kinetic. The thermodynamic study confirmed the suitability of NO3- removal by the as-prepared bioadsorbent at room temperature, and also the negative value of ΔGº = -89.1 kJ mol-1 demonstrating the spontaneous nature of adsorption.


Assuntos
Hidrogéis/química , Nitratos/química , Compostos de Amônio Quaternário/química , Tragacanto/química , Poluentes Químicos da Água/química , Adsorção , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/crescimento & desenvolvimento , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Hidrogéis/farmacologia , Concentração de Íons de Hidrogênio , Compostos de Amônio Quaternário/farmacologia , Temperatura Ambiente , Tragacanto/farmacologia , Purificação da Água/métodos
4.
Pol J Microbiol ; 68(4): 549-558, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31880898

RESUMO

Various microbial biomasses have been employed as biosorbents. Bacterial biomass has added advantages because of easy in production at a low cost. The study investigated the biosorption of iron from aqueous solutions by Bacillus subtilis. An optimum biosorption capacity of 7.25 mg of the metal per gram of the biosorbent was obtained by the Inductive Coupled Plasma Optical Emission Spectroscopy (ICP-OES) under the experimental conditions of initial metal concentration of 100 mg/l, pH 4.5, and biomass dose of 1 g/l at 30°C for 24 hrs. The data showed the best fit with the Freundlich isotherm model while following pseudo-first-order kinetics. Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) analysis confirmed iron biosorption as precipitates on the bacterial surface, and as a peak in the EDX spectrum. The functional hydroxyl, carboxyl, and amino groups that are involved in biosorption were revealed by the Fourier Transform Infrared spectroscopy (FTIR). The amorphous nature of the biosorbent for biosorption was indicated by the X-ray Diffraction (XRD) analysis. The biomass of B. subtilis exhibited a point zero charge (pHpzc) at 2.0.Various microbial biomasses have been employed as biosorbents. Bacterial biomass has added advantages because of easy in production at a low cost. The study investigated the biosorption of iron from aqueous solutions by Bacillus subtilis. An optimum biosorption capacity of 7.25 mg of the metal per gram of the biosorbent was obtained by the Inductive Coupled Plasma Optical Emission Spectroscopy (ICP-OES) under the experimental conditions of initial metal concentration of 100 mg/l, pH 4.5, and biomass dose of 1 g/l at 30°C for 24 hrs. The data showed the best fit with the Freundlich isotherm model while following pseudo-first-order kinetics. Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) analysis confirmed iron biosorption as precipitates on the bacterial surface, and as a peak in the EDX spectrum. The functional hydroxyl, carboxyl, and amino groups that are involved in biosorption were revealed by the Fourier Transform Infrared spectroscopy (FTIR). The amorphous nature of the biosorbent for biosorption was indicated by the X-ray Diffraction (XRD) analysis. The biomass of B. subtilis exhibited a point zero charge (pHpzc) at 2.0.


Assuntos
Bacillus subtilis/metabolismo , Compostos Ferrosos/metabolismo , Poluentes Químicos da Água/metabolismo , Adsorção , Bacillus subtilis/crescimento & desenvolvimento , Biodegradação Ambiental , Biomassa , Compostos Ferrosos/química , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/química
5.
Int J Food Microbiol ; 311: 108329, 2019 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-31669928

RESUMO

This study evaluated the synergetic inhibitory effects of ultrasound and nisin/carvacrol on spore germination, outgrowth, and subsequent growth of vegetative cell of Bacillus subtilis in laboratory medium and milk. Ultrasound pretreatment (3.33 W/mL, 15 min) and nisin/carvacrol (0.01%, 0.02%) synergistically inhibited spore germination, outgrowth, and vegetative growth of spores in laboratory medium. Whereas no such inhibitory effect was observed in milk even with a 10-fold increase in the concentration (1%) of nisin. Flow cytometry analysis showed that the germination capacities of ultrasound pretreated spores combined with nisin/carvacrol (67.3% and 30.5%, respectively) was lower than that of the untreated spores (95.1%). These results quantitatively revealed the inhibitory effect of the combined treatments which were confirmed by phase-bright spore observations at single cell level. In general, the current work identified the combined ultrasound-carvacrol treatment as an effective strategy to control spores and vegetative cells of B. subtilis in the laboratory medium and milk during abusive storage.


Assuntos
Bacillus subtilis/crescimento & desenvolvimento , Nisina/farmacologia , Esporos Bacterianos/crescimento & desenvolvimento , Animais , Sinergismo Farmacológico , Leite/microbiologia , Análise de Célula Única
6.
PLoS Genet ; 15(10): e1008263, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31626625

RESUMO

In Bacillus subtilis, the extracytoplasmic function σ factor σM regulates cell wall synthesis and is critical for intrinsic resistance to cell wall targeting antibiotics. The anti-σ factors YhdL and YhdK form a complex that restricts the basal activity of σM, and the absence of YhdL leads to runaway expression of the σM regulon and cell death. Here, we report that this lethality can be suppressed by gain-of-function mutations in yidC1 (spoIIIJ), which encodes the major YidC membrane protein insertase in B. subtilis. B. subtilis PY79 YidC1 (SpoIIIJ) contains a single amino acid substitution in a functionally important hydrophilic groove (Q140K), and this allele suppresses the lethality of high σM. Analysis of a library of YidC1 variants reveals that increased charge (+2 or +3) in the hydrophilic groove can compensate for high expression of the σM regulon. Derepression of the σM regulon induces secretion stress, oxidative stress and DNA damage responses, all of which can be alleviated by the YidC1Q140K substitution. We further show that the fitness defect caused by high σM activity is exacerbated in the absence of the SecDF protein translocase or σM-dependent induction of the Spx oxidative stress regulon. Conversely, cell growth is improved by mutation of specific σM-dependent promoters controlling operons encoding integral membrane proteins. Collectively, these results reveal how the σM regulon has evolved to up-regulate membrane-localized complexes involved in cell wall synthesis, and to simultaneously counter the resulting stresses imposed by regulon induction.


Assuntos
Bacillus subtilis/genética , Integrases/genética , Proteínas de Membrana Transportadoras/genética , Fator sigma/genética , Bacillus subtilis/crescimento & desenvolvimento , Membrana Celular/genética , Parede Celular/genética , Dano ao DNA/genética , Regulação Bacteriana da Expressão Gênica , Mutação/genética , Óperon/genética , Regiões Promotoras Genéticas , Regulon/genética
7.
PLoS Genet ; 15(10): e1008232, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31622331

RESUMO

In nature, most bacteria live in biofilms where they compete with their siblings and other species for space and nutrients. Some bacteria produce antibiotics in biofilms; however, since the diffusion of antibiotics is generally hindered in biofilms by extracellular polymeric substances, i.e., the biofilm matrix, their function remains unclear. The Bacillus subtilis yitPOM operon is a paralog of the sdpABC operon, which produces the secreted peptide toxin SDP. Unlike sdpABC, yitPOM is induced in biofilms by the DegS-DegU two-component regulatory system. High yitPOM expression leads to the production of a secreted toxin called YIT. Expression of yitQ, which lies upstream of yitPOM, confers resistance to the YIT toxin, suggesting that YitQ is an anti-toxin protein for the YIT toxin. The alternative sigma factor SigW also contributes to YIT toxin resistance. In a mutant lacking yitQ and sigW, the YIT toxin specifically inhibits biofilm formation, and the extracellular neutral protease NprB is required for this inhibition. The requirement for NprB is eliminated by Δeps and ΔbslA mutations, either of which impairs production of biofilm matrix polymers. Overexpression of biofilm matrix polymers prevents the action of the SDP toxin but not the YIT toxin. These results indicate that, unlike the SDP toxin and many conventional antibiotics, the YIT toxin can pass through layers of biofilm matrix polymers to attack cells within biofilms with assistance from NprB. When the wild-type strain and the YIT-sensitive mutant were grown together on a solid medium, the wild-type strain formed biofilms that excluded the YIT-sensitive mutant. This observation suggests that the YIT toxin protects B. subtilis biofilms against competitors. Several bacteria are known to produce antibiotics in biofilms. We propose that some bacteria including B. subtilis may have evolved specialized antibiotics that can function within biofilms.


Assuntos
Bacillus subtilis/genética , Proteínas de Bactérias/genética , Toxinas Bacterianas/genética , Biofilmes/crescimento & desenvolvimento , Antibacterianos/biossíntese , Bacillus subtilis/crescimento & desenvolvimento , Endopeptidases/genética , Regulação Bacteriana da Expressão Gênica/genética , Mutação , Óperon/genética
8.
Biocontrol Sci ; 24(3): 167-172, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31527348

RESUMO

Spores of Bacillus subtilis suspended in water or aqueous solution of NaCl, CaCl2, sodium lactate, or calcium lactate at pH 4 - 7 was subjected to spore inactivation by simultaneous combination of medium high hydrostatic pressure (MHHP; 100 MPa) treatment for germination and medium high temperature (MHT; 65℃) treatment for pasteurization of germinated vegetative cells. The spores at pH 4 in NaCl solution and those at pH 5 and 6 in Na lactate solutions were less killed than in water by MHHP+MHT treatment. Spore inactivation was promoted by calcium ion in NaCl solution at pH 4 and in Na lactate solutions at pH 5 and pH 6, while it was more suppressed at pH 5 and pH 6 in Na lactate solutions than at pH 4 in NaCl solution. The spores treated by MHHP+MHT in NaCl or Na lactate solution at pH 4 were further killed by subsequent MHT treatment.


Assuntos
Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Íons/metabolismo , Esporos Bacterianos/efeitos dos fármacos , Esporos Bacterianos/crescimento & desenvolvimento , Pressão Hidrostática , Temperatura Ambiente , Microbiologia da Água
9.
Curr Microbiol ; 76(12): 1487-1494, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31494740

RESUMO

Iturin A is a very important cyclic lipopeptide produced by several B. subtilis strains and has large commercial and therapeutic application potentials but its production on industrial scale has not been realized yet. In the present study, we have observed that the strain ET-1 of Bacillus subtilis, a producer of Iturin A, can present at least three different colony morphologies, which we arbitrarily called Rough, Smooth, and Mucoid morphotypes (R-, S-, and M-form). Performing HPLC analysis, a significant difference between the amounts of Iturin A produced by the three morphotypes was found. The morphotype R-form showed the highest productivity with yields about 10 and 100 times higher than morphotypes S and M, respectively. The results show that the production of Iturin A by B. subtilis could be strongly influenced by the phenotypic heterogeneity of cells within the inoculum. Indeed, we have observed that, pasteurizing the inoculum before seeding in order to improve the homogeneity removing the phenotypes less able to synthesize the Iturin A, its yields in a bench-scale production could be significantly improved. This can represent an important control factor also at industrial scale to improve the Iturin A yields, the robustness, the replicability, and consequently the cost-effectiveness of fermentation processes.


Assuntos
Bacillus subtilis/crescimento & desenvolvimento , Bacillus subtilis/metabolismo , Peptídeos Cíclicos/biossíntese , Reatores Biológicos/microbiologia , Fermentação , Fenótipo , Esporos Bacterianos/crescimento & desenvolvimento , Esporos Bacterianos/metabolismo
10.
Biosens Bioelectron ; 143: 111628, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31476599

RESUMO

A combined calorimetric gas- and spore-based biosensor array is presented in this work to monitor and evaluate the sterilization efficacy of gaseous hydrogen peroxide in aseptic filling machines. H2O2 has been successfully measured under industrial conditions. Furthermore, the effect of H2O2 on three different spore strains , namely Bacillus atrophaeus, Bacillus subtilis and Geobacillus stearothermophilus, has been investigated by means of SEM, AFM and impedimetric measurements. In addition, the sterilization efficacy of a spore-based biosensor and the functioning principle are addressed and discussed: the sensor array is convenient to be used in aseptic food industry to guarantee sterile packages.


Assuntos
Técnicas Biossensoriais , Calorimetria , Peróxido de Hidrogênio/isolamento & purificação , Esporos Bacterianos/efeitos dos fármacos , Bacillus/efeitos dos fármacos , Bacillus/crescimento & desenvolvimento , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/crescimento & desenvolvimento , Desinfetantes/química , Desinfetantes/isolamento & purificação , Gases/química , Gases/isolamento & purificação , Geobacillus stearothermophilus/efeitos dos fármacos , Geobacillus stearothermophilus/crescimento & desenvolvimento , Humanos , Peróxido de Hidrogênio/farmacologia , Infertilidade , Esporos Bacterianos/crescimento & desenvolvimento , Esterilização
11.
J Appl Microbiol ; 127(5): 1391-1402, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31386785

RESUMO

AIMS: This work aimed to evaluate the antimicrobial activity of pure (ZnO) and doped (ZnMgO) zinc oxide (ZnO) nanoparticles on bacterial pathogens and Saccharomyces cerevisiae to confirm their applicability as an alternative to antibiotics and to estimate their biocompatibility. METHODS AND RESULTS: Microbial growth inhibition on agar plates, microbial viability and adaptation tests in broth with ZnO nanoparticles, spore germination, random amplified polymorphic DNA and SDS-PAGE analysis were conducted to evaluate the effects of ZnO nanoparticles on cell morphology, viability, DNA damage and protein production. For this purpose, Escherichia coli, Salmonella, Listeria monocytogenes, Staphylococcus aureus, Bacillus subtilis and S. cerevisiae were studied after the addition of ZnO nanoparticles to the growth media. The contact with ZnO nanoparticles produced changes in morphology, shape, viability, DNA arrangement (DNA fingerprints) and protein content (SDS-PAGE) in treated cells. CONCLUSIONS: As reported in this study, ZnO nanoparticles have an antimicrobial effect on both prokaryotic and eukaryotic cells. Before using ZnO nanoparticles as antimicrobial agents, it is important to evaluate the target because their effect depends on their composition, size and dose. SIGNIFICANCE AND IMPACT OF THE STUDY: We believe that the results obtained can help to optimize manufactured metal oxide nanoparticles in terms of their composition, size and working concentration. The parameters obtained directly define the applicability and biocompatibility of ZnO nanoparticles and thus are essential for any utilization in food, medicine and industry where pathogen control is crucial.


Assuntos
Anti-Infecciosos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Nanopartículas/toxicidade , Saccharomyces cerevisiae/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Óxido de Zinco/farmacologia , Anti-Infecciosos/química , Bacillus subtilis/crescimento & desenvolvimento , Escherichia coli/crescimento & desenvolvimento , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Nanopartículas/química , Saccharomyces cerevisiae/crescimento & desenvolvimento , Staphylococcus aureus/crescimento & desenvolvimento , Óxido de Zinco/química
12.
Bioelectrochemistry ; 130: 107338, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31377394

RESUMO

During ohmic heating, the electric field may additionally inactivate bacterial endospores. However, the exact mechanism of action is unclear. Thus, a mechanistic study was carried out, investigating the possible target of electric fields inside the spore. Bacillus subtilis spores were heated by conventional and ohmic heating in a capillary system under almost identical thermal conditions. Wild-type (PS533) spores were used, as well as isogenic mutants lacking certain components known for their contribution to spores' heat resistance: small-acid soluble proteins (SASP) protecting DNA (PS578); the coat covering the spore (PS3328); and the spore germination enzyme SleB (FB122(+)). Treatment-dependent release of the spore core's depot of dipicolinic acid (DPA) was further evaluated. Up to 2.4 log10 additional inactivation of PS533 could be achieved by ohmic heating, compared to conventional heating. The difference varied for the mutants, with a decreasing difference indicating a decreased effect of the electric field and vice versa. In particular, mutant spores lacking SASPs showed a behavior more similar to thermal inactivation alone. The combination of heat and electric field was shown to be necessary for enhanced spore inactivation. Thus, it is hypothesized that either the heat treatment makes the spore susceptible to the electric field, or vice versa.


Assuntos
Bacillus subtilis/crescimento & desenvolvimento , Esporos Bacterianos/crescimento & desenvolvimento , Esterilização/métodos , Bacillus subtilis/genética , Proteínas de Bactérias/genética , Eletricidade , Calefação , Temperatura Alta , Mutação , Esporos Bacterianos/genética
13.
Eur J Med Chem ; 180: 143-153, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31302447

RESUMO

The rise of antibiotic resistance has necessitated the development of alternative strategies for the treatment of infectious diseases. Antimicrobial peptides (AMPs), components of the innate immune response in various organisms, are promising next-generation drugs against bacterial infections. The ability of the medicinal leech Hirudo medicinalis to store blood for months with little change has attracted interest regarding the identification of novel AMPs in this organism. In this study, we employed computational algorithms to the medicinal leech genome assembly to identify amino acid sequences encoding potential AMPs. Then, we synthesized twelve candidate AMPs identified by the algorithms, determined their secondary structures, measured minimal inhibitory concentrations against three bacterial species (Escherichia coli, Bacillus subtilis, and Chlamydia thrachomatis), and assayed cytotoxic and haemolytic activities. Eight of twelve candidate AMPs possessed antimicrobial activity, and only two of them, 3967 (FRIMRILRVLKL) and 536-1 (RWRLVCFLCRRKKV), exhibited inhibition of growth of all tested bacterial species at a minimal inhibitory concentration of 10 µmol. Thus, we evidence the utility of the developed computational algorithms for the identification of AMPs with low toxicity and haemolytic activity in the medicinal leech genome assembly.


Assuntos
Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Infecções Bacterianas/tratamento farmacológico , Farmacorresistência Bacteriana/efeitos dos fármacos , Algoritmos , Animais , Antibacterianos/química , Peptídeos Catiônicos Antimicrobianos/química , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/crescimento & desenvolvimento , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Chlamydia/efeitos dos fármacos , Chlamydia/crescimento & desenvolvimento , Relação Dose-Resposta a Droga , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Hirudo medicinalis , Humanos , Estrutura Molecular , Relação Estrutura-Atividade
14.
Biomed Res Int ; 2019: 9020178, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31275990

RESUMO

The ability of Aspergillus niger strain to reduce organic and mineral pollution as well as the toxicity of two tannery wastewaters, the unhairing effluent (UE) and the final effluent (FE), taken from a local Tunisian tannery and under nonsterile conditions, was studied. Raw effluents show alkaline pH ≥11; thus experiments were carried out at initial pH values and at pH adjusted to 6. Characterization of effluents also revealed high salt levels (EC > 17 mS/cm) and high organic matter content (25 g/L for the UE and 7.2 g/L for the FE) but a low biodegradability since BOD5 did not exceed 2.5 and 1.25 g/L for the UE and the FE, respectively. The results of the biological treatment showed that A. niger was able not only to grow at high pH and salinity values, but also to reduce organic and mineral pollutant load. After treatment, the COD reduction for the UE reached 90% and 70% at pH=6 and at initial pH (12.13), respectively. For the FE, the decrease of COD values reached 75% at pH=6 and 64% at initial pH (11.64). Monitoring of mineral pollution levels showed a reduction in chromium (Cr) concentrations reaching 70% for the FE. This was reflected by an increase of the biomass of A. niger from 9.25 g/L (control) to 9.84 g/L for the FE. To confirm the efficiency of the biological treatment using A. niger, phytotoxicity (tomato seeds) and microtoxicity (Escherichia coli and Bacillus subtilis) tests were carried out. Results of this monitoring showed an important decrease in the toxicity levels for both effluents.


Assuntos
Aspergillus niger/metabolismo , Bioensaio/métodos , Curtume , Águas Residuárias/microbiologia , Purificação da Água/métodos , Bacillus subtilis/crescimento & desenvolvimento , Biodegradação Ambiental , Análise da Demanda Biológica de Oxigênio , Escherichia coli/crescimento & desenvolvimento , Inativação Metabólica , Testes de Toxicidade , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/isolamento & purificação
15.
Nat Microbiol ; 4(10): 1716-1726, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31285586

RESUMO

The peptidoglycan cell wall is an essential structure for the growth of most bacteria. However, many are capable of switching into a wall-deficient L-form state in which they are resistant to antibiotics that target cell wall synthesis under osmoprotective conditions, including host environments. L-form cells may have an important role in chronic or recurrent infections. The cellular pathways involved in switching to and from the L-form state remain poorly understood. This work shows that the lack of a cell wall, or blocking its synthesis with ß-lactam antibiotics, results in an increased flux through glycolysis. This leads to the production of reactive oxygen species from the respiratory chain, which prevents L-form growth. Compensating for the metabolic imbalance by slowing down glycolysis, activating gluconeogenesis or depleting oxygen enables L-form growth in Bacillus subtilis, Listeria monocytogenes and Staphylococcus aureus. These effects do not occur in Enterococcus faecium, which lacks the respiratory chain pathway. Our results collectively show that when cell wall synthesis is blocked under aerobic and glycolytic conditions, perturbation of cellular metabolism causes cell death. We provide a mechanistic framework for many anecdotal descriptions of the optimal conditions for L-form growth and non-lytic killing by ß-lactam antibiotics.


Assuntos
Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/metabolismo , Carbono/metabolismo , Formas L/efeitos dos fármacos , Formas L/metabolismo , beta-Lactamas/farmacologia , Bacillus subtilis/genética , Bacillus subtilis/crescimento & desenvolvimento , Parede Celular/efeitos dos fármacos , Parede Celular/metabolismo , Transporte de Elétrons/genética , Enterococcus faecium/efeitos dos fármacos , Enterococcus faecium/crescimento & desenvolvimento , Enterococcus faecium/metabolismo , Gluconeogênese , Formas L/genética , Formas L/crescimento & desenvolvimento , Muramidase/farmacologia , Mutação , Penicilina G/farmacologia , Peptidoglicano/efeitos dos fármacos , Peptidoglicano/metabolismo , Sistema Fosfotransferase de Açúcar do Fosfoenolpiruvato/genética , Espécies Reativas de Oxigênio/metabolismo , Espécies Reativas de Oxigênio/toxicidade
16.
Chem Biodivers ; 16(9): e1900353, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31329336

RESUMO

Five known secondary metabolites, chrysophanol (1), 7,7'-biphyscion (2), secalonic acid D (3), mannitol (4) and trehalose (5) were isolated for the first time from the extracts of the fungus Phialomyces macrosporus. Their structures were elucidated by NMR methods (1D and 2D NMR analysis), optical activity and ESI-MS. Complete 1 H and 13 C assignments were performed for compound 2. The antimicrobial activity was evaluated by serial microdilution assay for compounds 2 and 3 and results showed that compound 3 exhibited a significant growth inhibition at concentrations of 15.6 mg/ml (S. aureus and S. choleraesius) and 0.97 mg/mL (B. subtilis), comparable to the positive control.


Assuntos
Antibacterianos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Salmonella/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Antraquinonas/química , Antraquinonas/isolamento & purificação , Antraquinonas/farmacologia , Antibacterianos/química , Antibacterianos/isolamento & purificação , Bacillus subtilis/crescimento & desenvolvimento , Relação Dose-Resposta a Droga , Espectroscopia de Ressonância Magnética , Manitol/química , Manitol/isolamento & purificação , Manitol/farmacologia , Testes de Sensibilidade Microbiana , Estrutura Molecular , Salmonella/crescimento & desenvolvimento , Staphylococcus aureus/crescimento & desenvolvimento , Trealose/química , Trealose/isolamento & purificação , Trealose/farmacologia , Xantonas/química , Xantonas/isolamento & purificação , Xantonas/farmacologia
17.
Mater Sci Eng C Mater Biol Appl ; 102: 623-633, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31147034

RESUMO

The current work deals with a time-dependent study to track the antibacterial action of electrodeposited Cu, Cu-SiC functionally graded coating (FGC) against Escherichia coli NCIM 2931 (Gram-negative) and Bacillus subtilis NCIM 2063 (Gram-positive). After 24 h of incubation, the Cu, Cu-SiC FGC causes 7 Escherichia coli NCIM 2931 and 10 Bacillus subtilis NCIM 2063 log reduction of planktonic cells. The outer membrane permeabilization experiment proves that the intake of excessive Cu ions leads to the damage of bacterial cell membrane followed by lipid degradation. The thiobarbituric acid reactive substances assay reveals that Cu ions released from the surface of Cu, Cu-SiC FGC triggers the oxidative degeneration of phospholipids (most abundant constituent of bacterial cell membrane). This was further cross-verified using atomic absorption spectroscopy. From 0 to 24 h, the bacterial morphology is characterized using transmission electron microscope and scanning electron microscope which shows the cytoplasmic leakage and cell death. The Cu, Cu-SiC FGC also exhibits hydrophobic surface (contact angle of 144°) which prevents the bacterial adherence to the surface and thus, inhibits them to penetrate into its bulk. The observed results of antibacterial and anti-adhesion properties of Cu, Cu-SiC FGC are compared with single-layered metallic Cu and Cu-SiC nanocomposite coatings. Hence, the electrodeposited Cu, Cu-SiC FGC has the potential to serve as an inexpensive touch surface alternative for the healthcare industries.


Assuntos
Membrana Celular/metabolismo , Materiais Revestidos Biocompatíveis/farmacologia , Galvanoplastia/métodos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Antibacterianos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/crescimento & desenvolvimento , Bacillus subtilis/ultraestrutura , Aderência Bacteriana/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Contagem de Colônia Microbiana , Cobre/metabolismo , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/ultraestrutura , Íons , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Fatores de Tempo
18.
Pol J Microbiol ; 68(1): 105-114, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31050258

RESUMO

Bacteria from the genus Bacillus are a rich source of commercial enzymes, including amylases, proteases, cellulases, glucose isomerase, and pullulanase. Cellulases account for 15% of the global market of industrial enzymes; thus, new microorganisms producing cellulases in a higher concentration and new ingredients, which can enhance the level of enzyme synthesis, are still needed. Many of cellulose-degrading microorganisms have been isolated so far and characterized in various regions of the world. In this study, we were looking for the bacteria isolated from the natural environment with the high cellulolytic potential, which could be used as components of a biopreparation to accelerate decomposition of postharvest leftovers in agriculture. The 214 bacterial strains were isolated from environmental samples rich in cellulose and their ability to synthesize cellulases were examined using the diffusion method. Six strains, which have the highest diameter of clearing zone both for biomass and supernatant, were selected for identification. Optimization of biosynthesis of the cellulose-degrading enzymes indicated that optimal temperature of this process fluctuated in the range of 21-42°C (depending on the strain and carbon source). The highest cellulolytic activity was observed for the isolates designed as 4/7 (identified as Bacillus subtilis) and 4/18 (identified as Bacillus licheniformis) in a temperature of 32°C. With the use of a desirability function methodology, the optimal medium composition to achieve a simple, cost-efficient process of cellulases production was developed for both strains. These experiments show that microorganisms isolated from natural environmental samples have unique properties and potential for commercial applications (e.g. for biopreparations production).Bacteria from the genus Bacillus are a rich source of commercial enzymes, including amylases, proteases, cellulases, glucose isomerase, and pullulanase. Cellulases account for 15% of the global market of industrial enzymes; thus, new microorganisms producing cellulases in a higher concentration and new ingredients, which can enhance the level of enzyme synthesis, are still needed. Many of cellulose-degrading microorganisms have been isolated so far and characterized in various regions of the world. In this study, we were looking for the bacteria isolated from the natural environment with the high cellulolytic potential, which could be used as components of a biopreparation to accelerate decomposition of postharvest leftovers in agriculture. The 214 bacterial strains were isolated from environmental samples rich in cellulose and their ability to synthesize cellulases were examined using the diffusion method. Six strains, which have the highest diameter of clearing zone both for biomass and supernatant, were selected for identification. Optimization of biosynthesis of the cellulose-degrading enzymes indicated that optimal temperature of this process fluctuated in the range of 21­42°C (depending on the strain and carbon source). The highest cellulolytic activity was observed for the isolates designed as 4/7 (identified as Bacillus subtilis) and 4/18 (identified as Bacillus licheniformis) in a temperature of 32°C. With the use of a desirability function methodology, the optimal medium composition to achieve a simple, cost-efficient process of cellulases production was developed for both strains. These experiments show that microorganisms isolated from natural environmental samples have unique properties and potential for commercial applications (e.g. for biopreparations production).


Assuntos
Bacillus licheniformis/enzimologia , Bacillus licheniformis/metabolismo , Bacillus subtilis/enzimologia , Bacillus subtilis/metabolismo , Celulases/metabolismo , Celulose/metabolismo , Bacillus licheniformis/crescimento & desenvolvimento , Bacillus licheniformis/isolamento & purificação , Bacillus subtilis/crescimento & desenvolvimento , Bacillus subtilis/isolamento & purificação , Biomassa , Nitrogênio/metabolismo , Microbiologia do Solo , Temperatura Ambiente
19.
Ecotoxicol Environ Saf ; 180: 384-395, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31103858

RESUMO

The present study aimed at assessment of different application methods of Bacillus subtilis MF497446 to induce development of cowpea ensuring food safety under cadmium (Cd) stress. Also, isolation, plant growth promoting (PGP) traits and 16 S rRNA-based identification of Bacillus subtilis MF497446 is documented. Out of 24 Bacillus isolates (AS1-AS24), only four isolates (AS4, AS12, AS14 and AS22) showed greater Cd tolerance up to 18 mg L-1. The greatest PGP traits under Cd stress were displayed by Bacillus isolate (AS12); which, also, enhanced seedling elongation and vigor index of cowpea under Cd stress. Phylogenetic analysis, based on 16 S rRNA, confirmed that this promising Bacillus isolate (AS12) belongs to Bacillus subtilis and is referred to as B. subtilis MF497446. Treatment of inoculation+soaking for 90 min of cowpea seeds by B. subtilis MF497446 resulted in the best development of cowpea plants under Cd stress (up to 9 mg kg-1); as fresh and dry masses of cowpea increased from 6.80 to 1.54 to 12.35 and 2.59 g plant-1, respectively. Moreover, shoot and root lengths were 19.66 and 28.33 cm when cowpea seeds were treated by B. subtilis MF497446 (inoculation+soaking for 90 min) compared to 11.33 and 10.66 cm, respectively, for control (Cd stress only). Application of B. subtilis MF497446 (as inoculation+soaking for 90 min) reduced Cd accumulation and bioconcentration factor in cowpea plants by 29.2 and 28.9%, respectively, compared to control (Cd stress only). These results clearly reveal that applying of B. subtilis MF497446 to crops grown on Cd-contaminated soil enhances plant growth and eliminates (or at least diminishes) the risks to human health ensuring food safety.


Assuntos
Bacillus subtilis/crescimento & desenvolvimento , Cádmio/análise , Inocuidade dos Alimentos , Poluentes do Solo/análise , Vigna/efeitos dos fármacos , Bacillus subtilis/isolamento & purificação , Biodegradação Ambiental , Cádmio/metabolismo , Rizosfera , Microbiologia do Solo , Poluentes do Solo/metabolismo , Vigna/crescimento & desenvolvimento , Vigna/metabolismo
20.
RNA Biol ; 16(7): 972-987, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31043113

RESUMO

CsrA is a widely conserved, abundant small RNA binding protein that has been found in E. coli and other Gram-negative bacteria where it is involved in the regulation of carbon metabolism, biofilm formation and virulence. CsrA binds to single-stranded GGA motifs around the SD sequence of target mRNAs where it inhibits or activates translation or influences RNA processing. Small RNAs like CsrB or CsrC containing 13-22 GGA motifs can sequester CsrA, thereby abrogating the effect of CsrA on its target mRNAs. In B. subtilis, CsrA has so far only been found to regulate one target, hag mRNA and to be sequestered by a protein (FliW) and not by an sRNA. Here, we employ a combination of in vitro and in vivo methods to investigate the effect of CsrA on the small regulatory RNA SR1 from B. subtilis, its primary target ahrC mRNA and its downstream targets, the rocABC and rocDEF operons. We demonstrate that CsrA can promote the base-pairing interactions between SR1 and ahrC mRNA, a function that has so far only been found for Hfq or ProQ. Abbreviations: aa, amino acid; bp, basepair; nt, nucleotide; PAA, polyacrylamide; SD, Shine Dalgarno.


Assuntos
Bacillus subtilis/metabolismo , Proteínas de Bactérias/metabolismo , RNA Bacteriano/metabolismo , Arginina/farmacologia , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/genética , Bacillus subtilis/crescimento & desenvolvimento , Pareamento de Bases/genética , Sequência de Bases , Carbono/farmacologia , Regulação Bacteriana da Expressão Gênica , Mutação/genética , Conformação de Ácido Nucleico , Regiões Promotoras Genéticas/genética , Ligação Proteica , Biossíntese de Proteínas , Estabilidade de RNA/genética , RNA Bacteriano/química , RNA Bacteriano/genética , RNA Mensageiro/química , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ribonucleases/metabolismo , Transcrição Genética
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