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1.
Arch Microbiol ; 204(1): 46, 2021 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-34932145

RESUMO

The present study characterized aresenate reductase of Bacillus thuringiensis KPWP1, tolerant to salt, arsenate and a wide range of pH during growth. Interestingly, it was found that arsC, arsB and arsR genes involved in arsenate tolerance are distributed in the genome of strain KPWP1. The inducible arsC gene was cloned, expressed and the purified ArsC protein showed profound enzyme activity with the KM and Kcat values as 25 µM and 0.00119 s-1, respectively. In silico studies revealed that in spite of 19-26% differences in gene sequences, the ArsC proteins of Bacillus thuringiensis, Bacillus subtilis and Bacillus cereus are structurally conserved and ArsC structure of strain KPWP1 is close to nature. Docking and analysis of the binding site showed that arsenate ion interacts with three cysteine residues of ArsC and predicts that the ArsC from B. thuringiensis KPWP1 reduces arsenate by using the triple Cys redox relay mechanism.


Assuntos
Arseniato Redutases , Bacillus thuringiensis , Arseniato Redutases/genética , Arseniatos , Arsênio , Bacillus cereus , Bacillus subtilis , Bacillus thuringiensis/enzimologia , Bacillus thuringiensis/genética , Proteínas de Bactérias/genética , Concentração de Íons de Hidrogênio , Tolerância ao Sal
2.
Food Res Int ; 149: 110658, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34600660

RESUMO

Microbiological safety in food industry are always a concern regarding sublethal tolerance in bacteria for common and natural sanitizers. Natural bacteriocins, such as nisin (NIS), may negatively interfere in the efficiency of major compounds of essential oils against foodborne pathogenic bacteria. However, nanoemulsioned forms increase the bactericidal potential of natural compounds acting synergistically. In this study, cinnamaldehyde (CIN), citral (CIT), and linalool (LIN) were evaluated independently, associated with NIS, and in nanoemulsions (NEs) against Bacillus cereus using untargeted-metabolomics. Results revealed morphological changes in the structure of B. cereus treated with NEs of CIN and CIT, both NIS-associated. In addition, sensibility tests and UHPLC-QTOF-MS analyses indicated that NIS might react together with CIT reducing the bactericidal efficiency, while the nanoemulsion of CIT effect was enhanced by NIS in nanoemulsioned forms. This study highlights the importance of prudent administration of natural compounds as antimicrobial agents to prevent sublethal tolerance in pathogenic bacteria.


Assuntos
Bacteriocinas , Óleos Voláteis , Antibacterianos/farmacologia , Bacillus cereus , Metabolômica , Óleos Voláteis/farmacologia
3.
Int J Food Microbiol ; 360: 109420, 2021 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-34602293

RESUMO

In this study, the effect of pH, alone or in combination with temperature, on the maximum growth rate (µmax) of B. cereus sensu lato was investigated. In phase 1, the effect of pH at 30 °C was studied for 16 mesophilic strains and 2 psychrotrophic strains of Bacillus cereus sensu lato. The µmax vs. pH relationship was found to show a similar pattern for all the strains. Several pH models from literature were evaluated and the best performing 'growth rate vs. pH' model selected. A stochastic model was then developed to predict the maximum specific growth rate of mesophilic B. cereus at 30 °C as a function of pH, the intra-species variability being incorporated via considering the model parameters (e.g. pHmin) randomly distributed. The predicted maximum specific growth rates were acceptably close to independent published data. In phase 2, the combined effects of temperature and pH were studied. Growth rates were also generated at 15, 20 and 40 °C for a selection of strains and the pH model was fitted at each temperature. Interestingly, the results showed that the estimates for the pHmin parameter for mesophilic strains were lower at 20-30 °C than near the optimum temperature (40 °C), suggesting that experiments for the determination of this parameter should be conducted at lower-than-optimum temperatures. New equations were proposed for the relationship between temperature and the minimum pH-values, which were also consistent with the experimental growth boundaries. The parameters defining this equation quantify the minimum temperature for growth observed experimentally, the temperature of maximum enzyme stability and the maximum temperature for growth. Deviations from the Gamma hypothesis (multiplicative effects of environmental factors on the maximum specific growth rate) were observed near the growth limits, especially at 40 °C. To improve model performance, two approaches, one based on a minimum pH-term (doi: https://doi.org/10.3389/fmicb.2019.01510) and one based on an interaction term (doi: http://dx.doi.org/10.1016/S0168-1605(01)00640-7) were evaluated.


Assuntos
Bacillus cereus , Concentração de Íons de Hidrogênio , Temperatura
4.
J Agric Food Chem ; 69(41): 12219-12229, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34632761

RESUMO

Foods contaminated by harmful substances such as bacteria and viruses have caused more than 200 kinds of diseases, ranging from diarrhea to cancer. Among them, Bacillus cereus (B. cereus) is a foodborne pathogen that commonly contaminates raw meat, fresh vegetables, rice, and uncooked food. The current chemical preservatives may have adverse effects on food and even human health. Therefore, natural antibacterial agents are sought after as alternative preservatives. Stilbene compounds, including pterostilbene (PT), pinostilbene (PS), and piceatannol (PIC), which have many health benefits and exhibit antibacterial activity, were tested against B. cereus. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of PT, PS, and PIC against B. cereus ranged from 25 to 100 µg/mL. From the time-kill curve assay, PT reduced B. cereus cell survival, increased intracellular reactive oxygen species (ROS), and induced apoptosis-like cell death (ALD) in a dose-dependent manner. The quantitative real-time polymerase chain reaction (qPCR) results confirmed that treatment with PT induced genetic changes related to ALD, such as an increase in RecA gene expression and a decrease in LexA gene expression. In addition, PT showed a beneficial effect on the gut microbiota that increased the abundance of Bacteroidetes and lowered the abundance of Firmicutes. Taken together, our results showed that PT has antibacterial effects against B. cereus via ALD and is beneficial for promoting healthy gut microbiota that is worthy for the development of antibacterial agents for the food industry.


Assuntos
Microbioma Gastrointestinal , Estilbenos , Antibacterianos/farmacologia , Apoptose , Bacillus cereus , Morte Celular , Microbiologia de Alimentos , Humanos , Estilbenos/farmacologia
6.
Artigo em Inglês | MEDLINE | ID: mdl-34494947

RESUMO

Three Gram-positive bacterial strains, BML-BC004, BML-BC017 and BML-BC059, isolated from blood samples from three inpatients in Japan, were identified as members of Bacillus cereus using matrix-assisted laser desorption ionization time-of-flight MS. The 16S rRNA gene sequences of these three strains were more than 97.1 % similar to 18 type strains belonging to the B. cereus group. Whole-genome comparisons, using average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH), confirmed that the three strains represented three individual distinct species belonging to the B. cereus group. A phylogenetic tree showed that BML-BC004, BML-BC017 and BML-BC059 were located close to B. luti, B. mobilis and B. paramycoides, respectively. Based on these phylogenetic and phenotypic data, including values below the threshold for ANI and dDDH, the three strains should be classified as representing three different novel species of the B. cereus group: Bacillus sanguinis sp. nov., with type strain BML-BC004T (=DSM 111102T=JCM 34122T), Bacillus paramobilis sp. nov., with type strain BML-BC017T (=DSM 111100T=JCM 34124T) and Bacillus hominis sp. nov., with type strain BML-BC059T (=DSM 111101T=JCM 34125T).


Assuntos
Bacillus cereus/classificação , Sangue/microbiologia , Filogenia , Bacillus cereus/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Humanos , Japão , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
7.
Biocontrol Sci ; 26(3): 147-155, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34556617

RESUMO

In this study, spore heat resistance and growth ability at refrigeration temperatures of Bacillus spp. and Paenibacillus spp. were determined. The spore D90°C of 67.6% (23 of 34 strains) of Bacillus and 73.9% (17 of 23 strains) of Paenibacillus was less than 15 min. The growth abilities of both genera were equivalent at 10°C. However, 71.1% (32 of 45 strains) of Paenibacillus and only 6.3% (3 of 48 strains) of Bacillus cereus group could grow at 4°C. Eight B. cereus strains formed spores with higher heat resistance compared to the other Bacillus strains assessed; however, they did not grow at tempreratures below 10°C. Conversely, four Paenibacillus strains formed spores with heat resistance equivalent to that of the eight B. cereus strains and grew at 6°C or lower. In particular, Paenibacillus sp. JCM13343 formed the highest heat-resistant spores (D90°C = 136.1 min) and grew well at 4°C. These results indicate that Paenibacillus can grow in processed foods during refrigerated storage and has the potential to cause spoilage as well as Bacillus. Therefore, Paenibacillus should be considered as one of the targets for microbiological control in refrigerated processed foods.


Assuntos
Bacillus , Paenibacillus , Bacillus cereus , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Temperatura Alta , Refrigeração , Esporos Bacterianos , Temperatura
8.
Food Res Int ; 148: 110625, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34507769

RESUMO

The inactivation of pathogenic microorganisms in water and high transmittance liquid foods has been studied extensively. The efficiency of the process is relatively low for treating opaque liquid foods using traditional UV systems. This study evaluated the ability of UV-C light to inactivate foodborne pathogens in a simulated opaque fluid (6.5 to 17 cm-1) at commercial relevant flow rates (31.70, 63.40, 95.10 gph) using a pilot-scale Dean Flow UV system. In this study, a mathematical model for the prediction of delivered fluence was developed by the biodosimetry method. The results revealed that increased Reduction equivalent fluence (REF) rates were observed with increased flow rates due to additional turbulence. The experimental and calculated REF were well correlated with the UV-C absorption coefficient range of 6.5 to 17 cm-1 indicating efficient mixing in the reactor. REF scaled up linearly at experimental conditions as an inverse function of flow rate and absorption coefficient, and a linear mathematical model (R2 > 0.99, p < 0.05) to predict delivered REF was developed. The model was tested and validated against independent experiments using Salmonella Typhimurium and Bacillus cereus endospores. The predicted and experimental REF values were in close agreement (p > 0.05). It is demonstrated that the developed model can predict the REF, thus microbial inactivation of microbial suspensions in simulated fluid with the absorption coefficient of 6.5-17 cm-1 and flow rates of 31.70-95.10 gph. The pilot system will be field-tested against microorganisms in highly absorbing and scattering fluids.


Assuntos
Esporos Bacterianos , Raios Ultravioleta , Bacillus cereus , Viabilidade Microbiana , Salmonella typhimurium
9.
Antonie Van Leeuwenhoek ; 114(11): 1759-1770, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34491485

RESUMO

Bacillus thuringiensis is the most successful microbial insecticide against different pests in agriculture and vectors of diseases. Its activity is mostly attributed to the Cry proteins expressed during its sporulation phase. However, these proteins are not exclusive to B. thuringiensis. Some cry genes have been found in other Bacillus species, or even in other genera. In this work, cry genes were searched in 223 acrystalliferous bacillaceous strains. From these strains 13 amplicons were obtained, cloned, and sequenced; however, only 6 amplicons tested positive for cry-like genes, and the 6 isolates showed to be the same strain. We report the characterization of an unusual strain of B. cereus (LBIC-004) which is unable to form protein inclusions during the sporulation phase. LBIC-004 showed a high identity to B. cereus using the sequences of 16S rRNA, gyrB and hag genes; in addition, a unique plasmid pattern of the strain was obtained. A 1953-bp cry gene was identified, coding for a 651 amino acid protein with a molecular weight of 74.9 kDa. This protein showed a predicted three-domain structure, similar to all Cry proteins. However, the amino acid sequence of the protein showed only 41% identity its highest hit: the Cry8Ca1 protein, indicating the uniqueness of this cry-like gene. It was cloned and transferred into a mutant acrystalliferous B. thuringiensis strain which was used in bioassays against Caenorhabditis elegans, Aedes aegypti, Manduca sexta and Phyllophaga sp. The recombinant strain showed no crystal formation and no toxicity to the tested species.


Assuntos
Bacillus cereus , Bacillus thuringiensis , Bacillus cereus/genética , Bacillus thuringiensis/genética , Proteínas de Bactérias/genética , Plasmídeos , RNA Ribossômico 16S/genética
10.
BMC Genomics ; 22(1): 648, 2021 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-34493209

RESUMO

BACKGROUND: Bacillus cereus is a notorious foodborne pathogen, which can grow under anoxic conditions. Anoxic growth is supported by endogenous redox metabolism, for which the thiol redox proteome serves as an interface. Here, we studied the cysteine (Cys) proteome dynamics of B. cereus ATCC 14579 cells grown under fermentative anoxic conditions. We used a quantitative thiol trapping method combined with proteomics profiling. RESULTS: In total, we identified 153 reactive Cys residues in 117 proteins participating in various cellular processes and metabolic pathways, including translation, carbohydrate metabolism, and stress response. Of these reactive Cys, 72 were detected as reduced Cys. The B. cereus Cys proteome evolved during growth both in terms of the number of reduced Cys and the Cys-containing proteins identified, reflecting its growth-phase-dependence. Interestingly, the reduced status of the B. cereus thiol proteome increased during growth, concomitantly to the decrease of extracellular oxidoreduction potential. CONCLUSIONS: Taken together, our data show that the B. cereus Cys proteome during unstressed fermentative anaerobic growth is a dynamic entity and provide an important foundation for future redox proteomic studies in B. cereus and other organisms.


Assuntos
Bacillus cereus , Proteoma , Anaerobiose , Oxirredução , Proteoma/metabolismo , Proteômica , Compostos de Sulfidrila
11.
Arch Virol ; 166(11): 3183-3188, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34505918

RESUMO

A new Bacillus cereus phage, SWEP1, was isolated from black soil. The host lysis activity of phage SWEP1 has a relatively short latent time (20 min) and a small burst size of 83 PFU. The genome of SWEP1 consists of 162,461 bp with 37.77% G+C content. The phage encodes 278 predicted proteins, 103 of which were assigned functionally. No tRNA genes were found. Comparative genomics analysis indicated that SWEP1 is related to Bacillus phage B4 (86.91% identity, 90% query coverage). Phenotypic and genotypic characterization suggested that SWEP1 is a new member of a new species in the genus Bequatrovirus, family Herelleviridae.


Assuntos
Fagos Bacilares/fisiologia , Bacillus cereus/virologia , Genoma Viral , Fagos Bacilares/genética , Fagos Bacilares/isolamento & purificação , Bacillus cereus/isolamento & purificação , Composição de Bases , Replicação do DNA/genética , Genômica , Genótipo , Microscopia Eletrônica de Transmissão , Filogenia , RNA de Transferência/genética , Microbiologia do Solo , Temperatura
12.
Appl Microbiol Biotechnol ; 105(14-15): 5943-5957, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34350477

RESUMO

Bacillus cereus 905, originally isolated from wheat rhizosphere, exhibits strong colonization ability on wheat roots. Our previous studies showed that root colonization is contributed by the ability of the bacterium to efficiently utilize carbon sources and form biofilms and that the sodA2 gene-encoded manganese-containing superoxide dismutase (MnSOD2) plays an indispensable role in the survival of B. cereus 905 in the wheat rhizosphere. In this investigation, we further demonstrated that the ability of B. cereus 905 to resist adverse environmental conditions is partially attributed to activation of the alternative sigma factor σB, encoded by the sigB gene. The sigB mutant experienced a dramatic reduction in survival when cells were exposed to ethanol, acid, heat, and oxidative stress or under glucose starvation. Analysis of the sodA2 gene transcription revealed a partial, σB-dependent induction of the gene during glucose starvation or when treated with paraquat. In addition, the sigB mutant displayed a defect in biofilm formation under stress conditions. Finally, results from the root colonization assay indicated that sigB and sodA2 collectively contribute to B. cereus 905 colonization on wheat roots. Our study suggests a diverse role of SigB in rhizosphere survival and root colonization of B. cereus 905 under stress conditions. KEY POINTS : • SigB confers resistance to environmental stresses in B. cereus 905. • SigB plays a positive role in glucose utilization and biofilm formation in B. cereus. • SigB and SodA2 collectively contribute to colonization on wheat roots by B. cereus.


Assuntos
Bacillus cereus , Glucose , Bacillus cereus/genética , Proteínas de Bactérias/genética , Biofilmes , Fator sigma , Superóxido Dismutase
13.
Molecules ; 26(15)2021 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-34361550

RESUMO

Efficient use of herbicides for plant protection requires the application of auxiliary substances such as surfactants, stabilizers, wetting or anti-foaming agents, and absorption enhancers, which can be more problematic for environment than the herbicides themselves. We hypothesized that the combination of sulfonylurea (iodosulfuron-methyl) anion with inexpensive, commercially available quaternary tetraalkylammonium cations could lead to biologically active ionic liquids (ILs) that could become a convenient and environment-friendly alternative to adjuvants. A simple one-step synthesis allowed for synthesizing iodosulfuron-methyl based ILs with high yields ranging from 88 to 96% as confirmed by UV, FTIR, and NMR. The obtained ILs were found to possess several favorable properties compared to the currently used sodium salt iodosulfuron-methyl, such as adjustable hydrophobicity (octanol-water partition coefficient) and enhanced stability in aqueous solutions, which was supported by molecular calculations showing cation-anion interaction energies. In addition, soil mobility and volatility of ILs were more beneficial compared to the parental herbicide. Herbicidal activity tests toward oil-seed rape and cornflower revealed that ILs comprising at least one alkyl chain in the decyl to octadecyl range had similar or better efficacy compared to the commercial preparation without addition of any adjuvant. Furthermore, results of antimicrobial activity indicated that they were practically harmless or slightly toxic toward model soil microorganisms such as Pseudomonas putida and Bacillus cereus.


Assuntos
Anti-Infecciosos/química , Herbicidas/química , Líquidos Iônicos/química , Sulfonamidas/química , Compostos de Sulfonilureia/química , Tensoativos/química , Anti-Infecciosos/farmacologia , Bacillus cereus/crescimento & desenvolvimento , Herbicidas/farmacologia , Pseudomonas putida/crescimento & desenvolvimento , Compostos de Sulfonilureia/farmacologia
14.
Int J Med Mushrooms ; 23(6): 69-77, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34369735

RESUMO

In this study, samples of polypore mushroom Laetiporus conifericola were collected from Pennsylvania, USA. The antimicrobial activity (AMA) of ethanolic, methanolic, and water extracts of this fungus were tested in vitro by the agar diffusion test against some selected clinically important microorganisms. These microorganisms included three Gram-positive bacteria (Staphylococcus aureus 5W1941, S. epidermidis 85W1940, and Bacillus cereus 85W1815), three Gram-negative bacteria (Escherichia coli 85W1860, Salmonella typhimurium 85W1956, and Pseudomonas aeruginosa 85W1903), and one fungus (Candida albicans). These extracts demonstrated varying degrees of inhibition against all of the test pathogenic microorganisms except C. albicans. Methanolic and ethanolic extracts of L. conifericola were very effective against S. aureus, while the aqueous extract was the least effective. All tested extracts were effective against S. epidermidis, methanolic extract produced the best zone of inhibition followed by the aqueous extract while ethanolic extract had the least zone of inhibition. B. cereus and P. aeruginosa were highly susceptible to ethanol extract. In addition, the growth of E. coli was best inhibited by the aqueous extract, followed by the methanolic and ethanolic extracts, respectively. The aqueous and methanolic extracts were most effective against S. typhimurium; however, this bacterium was not susceptible to ethanolic extract. The significance of these findings is discussed.


Assuntos
Polyporales , Antibacterianos/farmacologia , Bacillus cereus , Escherichia coli , Testes de Sensibilidade Microbiana , Extratos Vegetais/farmacologia , Staphylococcus aureus , Estados Unidos
15.
PLoS One ; 16(8): e0253106, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34388169

RESUMO

A potential pesticide degrading bacterial isolate (2D), showing maximum tolerance (450 mg∙L-1) for cypermethrin, fipronil, imidacloprid and sulfosulfuron was recovered from a pesticide contaminated agricultural field. The isolate degraded cypermethrin, imidacloprid, fipronil and sulfosulfuron in minimal salt medium with 94, 91, 89 and 86% respectively as revealed by high performance liquid chromatography (HPLC) and gas chromatography (GC) analysis after 15 days of incubation. Presence of cyclobutane, pyrrolidine, chloroacetic acid, formic acid and decyl ester as major intermediate metabolites of cypermethrin biodegradation was observed in gas chromatography mass spectrometry (GC-MS) analysis. Results based on 16S rDNA sequencing, and phylogenetic analysis showed maximum similarity of 2D with Bacillus cereus (Accession ID: MH341691). Stress responsive and catabolic/pesticide degrading proteins were over expressed in the presence of cypermethrin in bacteria. Enzymatic kinetics of laccase was deduced in the test isolate under normal and pesticide stress conditions which suggested that the production of enzyme was induced significantly in pesticide stress (163 µg.µL-1) as compare to normal conditions(29 µg.µL-1) while the Km value was decreased in pesticides stress condition (Km = 10.57 mM) and increases in normal condition (Km = 14.33 mM).Amplification of laccase gene showed a major band of 1200bp. The present study highlights on the potential of 2D bacterial strain i.e., high tolerance level of pesticide, effective biodegradation rate, and presence of laccase gene in bacterial strain 2D, could become a potential biological agent for large-scale treatment of mixture of pesticide (cypermethrin, fipronil, imidacloprid and sulfosulfuron) in natural environment (soil and water).


Assuntos
Bacillus cereus/metabolismo , Proteínas de Bactérias/metabolismo , Praguicidas/farmacologia , Proteômica , Piretrinas/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Bacillus cereus/classificação , Cromatografia Líquida de Alta Pressão , Cromatografia Gasosa-Espectrometria de Massas
16.
J Food Prot ; 84(9): 1555-1559, 2021 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-34380146

RESUMO

ABSTRACT: In this study, Bacillus cereus was isolated from soft soybean curds, and a dynamic model was developed to describe the kinetic behavior of these isolates during transfer and storage. B. cereus isolates recovered from soft soybean curds were inoculated into soft soybean curd, and the levels were determined during storage at 10 to 30°C. The B. cereus counts were fitted to the Baranyi model to calculate maximum growth rate (µmax) and lag-phase duration (LPD). These kinetic parameters were then analyzed with a polynomial equation to evaluate the effects of temperature on the kinetic parameters. The developed model was validated with observed values, and the differences between predicted and observed values were determined by calculating the root mean square error (RMSE). A dynamic model was then developed with a combination of primary and secondary models to describe B. cereus growth under changing temperature conditions. B. cereus was detected in two soft soybean curd samples (5.1%) at 0.7 log CFU/g. The µmax was -0.04 to 0.47 log CFU/g/h, and the ln(LPD) was 3.94 to 0.04 h, depending on the storage temperature. The model performance was appropriate with a 0.216 RMSE and accurately described the kinetic behavior of B. cereus in soft soybean curd samples. These results suggest that B. cereus can contaminate soft soybean curds and that the models developed with the B. cereus isolates are useful for describing the kinetic behavior of B. cereus in soft soybean curd.


Assuntos
Bacillus cereus , Soja , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Temperatura
17.
Molecules ; 26(11)2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-34206015

RESUMO

New polymer-bioactive compound systems were obtained by immobilization of triazole derivatives onto grafted copolymers and grafted copolymers carrying betaine units based on gellan and N-vinylimidazole. For preparation of bioactive compound, two new types of heterocyclic thio-derivatives with different substituents were combined in a single molecule to increase the selectivity of the biological action. The 5-aryl-amino-1,3,4 thiadiazole and 5-mercapto-1,2,4-triazole derivatives, each containing 2-mercapto-benzoxazole nucleus, were prepared by an intramolecular cyclization of thiosemicarbazides-1,4 disubstituted in acidic and basic medium. The structures of the new bioactive compounds were confirmed by elemental and spectral analysis (FT-IR and 1H-NMR). The antimicrobial activity of 1,3,4 thiadiazoles and 1,2,4 triazoles was tested on gram-positive and gram-negative bacteria. The triazole compound was chosen to be immobilized onto polymeric particles by adsorption. The Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherm were used to describe the adsorption equilibrium. Also, the pseudo-first and pseudo-second models were used to elucidate the adsorption mechanism of triazole onto grafted copolymer based on N-vinylimidazole and gellan (PG copolymer) and grafted copolymers carrying betaine units (PGB1 copolymer). In vitro release studies have shown that the release mechanism of triazole from PG and PGB1 copolymers is characteristic of an anomalous transport mechanism.


Assuntos
Antibacterianos/síntese química , Betaína/química , Polissacarídeos Bacterianos/química , Triazóis/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Bacillus cereus/efeitos dos fármacos , Bacillus subtilis/efeitos dos fármacos , Ciclização , Escherichia coli/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Salmonella enteritidis/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Triazóis/química , Triazóis/farmacologia
18.
Acta Sci Pol Technol Aliment ; 20(3): 253-263, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34304544

RESUMO

BACKGROUND: The diet of most of the population is limited to a reduced number of plants, even in areas that have a varied and extensive diversity, such as Brazil. Unconventional Food Plants (UFPs) are plants considered exotic, native, and wild that grow naturally and can be used as food. Among these is Talinum paniculatum (Jacq.) Gaertn., which is widespread throughout Brazil and can be a potential source of nutrients. Due to the potential of utilization of UFPs in human food and the lack of studies regarding the composition of T. paniculatum, this study aimed to assess the nutritional value of T. paniculatum leaves, their antioxidant capacity, and their antimicrobial activity for possible use in food. METHODS: The characterization of the leaves of T. paniculatum was carried out through analyses of proximal composition, color, ascorbic acid, mineral profile, and antinutritional factors showing the presence of condensed and hydrolysable tannins and nitrates in low concentrations. Solvents of water, ethanol, ethanol/water, methanol, methanol/water, methanol/acetic acid and acetone/water/acetic acid were used to evaluate the extraction yield of phenolic compounds, antioxidant capacity, and antibacterial activity of the extracts. RESULTS: High contents of protein (18.61 g 100 g-1), insoluble dietary fiber (34.75 g 100 g-1), ascorbic acid (81.03 mg 100 g-1), magnesium, potassium, and calcium (649.600, 411.520 and 228.117 mg 100 g-1, respectively) were observed. Extraction using the mixture of solvents of methanol/acetic acid showed the highest yield of phenolic compounds (432.73 mg EAG 100 g-1) and antioxidant capacity using the DPPH assay (3144.92 mg 100 g-1). Bacillus cereus growth was inhibited by the T. paniculatum extracts. CONCLUSIONS: T. paniculatum leaves are a source of nutrients and their extracts have antioxidant and antibacterial potentials which can be used as supplements in food to improve one's health.


Assuntos
Antibacterianos/farmacologia , Antioxidantes/farmacologia , Caryophyllales/química , Nutrientes/análise , Valor Nutritivo , Extratos Vegetais/farmacologia , Folhas de Planta/química , Antibacterianos/análise , Antioxidantes/análise , Bacillus cereus/efeitos dos fármacos , Bacillus cereus/crescimento & desenvolvimento , Compostos de Bifenilo/metabolismo , Brasil , Dieta , Fenóis/análise , Fenóis/farmacologia , Picratos/metabolismo , Extratos Vegetais/química , Plantas Comestíveis/química
19.
Int J Mol Sci ; 22(14)2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34299167

RESUMO

At the end of exponential growth, aerobic bacteria have to cope with the accumulation of endogenous reactive oxygen species (ROS). One of the main targets of these ROS is cysteine residues in proteins. This study uses liquid chromatography coupled to high-resolution tandem mass spectrometry to detect significant changes in protein abundance and thiol status for cysteine-containing proteins from Bacillus cereus during aerobic exponential growth. The proteomic profiles of cultures at early-, middle-, and late-exponential growth phases reveals that (i) enrichment in proteins dedicated to fighting ROS as growth progressed, (ii) a decrease in both overall proteome cysteine content and thiol proteome redox status, and (iii) changes to the reduced thiol status of some key proteins, such as the transition state transcriptional regulator AbrB. Taken together, our data indicate that growth under oxic conditions requires increased allocation of protein resources to attenuate the negative effects of ROS. Our data also provide a strong basis to understand the response mechanisms used by B. cereus to deal with endogenous oxidative stress.


Assuntos
Bacillus cereus/metabolismo , Cisteína/análise , Cisteína/metabolismo , Estresse Oxidativo , Proteoma/análise , Proteoma/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Bacillus cereus/crescimento & desenvolvimento , Oxirredução , Proteômica/métodos
20.
Environ Pollut ; 288: 117814, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34329069

RESUMO

Known as a cause of food poisoning, Bacillus cereus (B. cereus) is widespread in nature. Cereulide, the heat-stable and acid-resistant emetic toxin which is produced by some B. cereus strains, is often associated with foodborne outbreaks, and causes acute emetic toxicity at high dosage exposure. However, the toxicological effect and underlying mechanism caused by chronic low-dose cereulide exposure require to be further addressed. In the study, based on mouse model, cereulide exposure (50 µg/kg body weight) for 28 days induced intestinal inflammation, gut microbiota dysbiosis and food intake reduction. According to the cell models, low dose cereulide exposure disrupted the intestinal barrier function and caused intestinal inflammation, which were resulted from endoplasmic reticulum (ER) stress IRE1/XBP1/CHOP pathway activation to induce cell apoptosis and inflammatory cytokines production. For gut microbiota, cereulide decreased the abundances of Lactobacillus and Oscillospira. Furthermore, cereulide disordered the metabolisms of gut microbiota, which exhibited the inhibitions of butyrate and tryptophan. Interestingly, cereulide exposure also inhibited the tryptophan hydroxylase to produce the serotonin in the gut and brain, which might lead to depression-like food intake reduction. Butyrate supplementation (100 mg/kg body weight) significantly reduced intestinal inflammation and serotonin biosynthesis suppression caused by cereulide in mice. In conclusion, chronic cereulide exposure induced ER stress to cause intestinal inflammation, gut microbiota dysbiosis and serotonin biosynthesis suppression. IRE1 could be the therapeutic target and butyrate supplementation is the potential prevention strategy.


Assuntos
Microbioma Gastrointestinal , Animais , Bacillus cereus , Depsipeptídeos , Disbiose/induzido quimicamente , Contaminação de Alimentos/análise , Inflamação/induzido quimicamente , Camundongos
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