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1.
Life Sci ; 254: 117754, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32389833

RESUMO

The most prevalent gastrointestinal (GI) cancers include colorectal cancer, stomach cancer, and liver cancer, known as the most common causes of cancer-related death in both men and women populations in the world. Traditional therapeutic approaches, including surgery, radiotherapy, and chemotherapy have failed in the effective treatment of cancer. Therefore, there is an urgent need for finding new effective anticancer agents. The available evidence and also the promising results of using bacteria as the anticancer agents on numerous cancer cell lines have attracted the attention of scientists for the therapeutic role of bacteria in the field of cancer therapy. Moreover, several studies on the bacteriotherapy agents have used genetic engineering to overcome the challenges and enhance the efficacy with the least drawbacks. Numerous bacterial species that can specifically target and internalize into the tumor cells are used live, attenuated, or genetically as compared to selectively consider the hypoxic condition of tumor, which results in the tumor suppression. The present study is a comprehensive review of the current literature on the use of bacteria and their substances such as bacteriocins and toxins in the treatment of different types of gastrointestinal cancers.


Assuntos
Antineoplásicos/uso terapêutico , Bactérias/metabolismo , Neoplasias Gastrointestinais/terapia , Bacteriocinas/farmacologia , Neoplasias Colorretais/tratamento farmacológico , Microbioma Gastrointestinal/efeitos dos fármacos , Engenharia Genética , Terapia Genética , Humanos , Neoplasias Hepáticas/tratamento farmacológico , Resultado do Tratamento
2.
PLoS One ; 15(5): e0233301, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32469926

RESUMO

Bacterial spot is a destructive disease of tomato in Florida that prior to the early 1990s was caused by Xanthomonas euvesicatoria. X. perforans was first identified in Florida in 1991 and by 2006 was the only xanthomonad associated with bacterial spot disease in tomato. The ability of an X. perforans strain to outcompete X. euvesicatoria both in vitro and in vivo was at least in part associated with the production of three bacteriocins designated Bcn-A, Bcn-B, and Bcn-C. The objective of this study was to characterize the genetic determinants of these bacteriocins. Bcn-A activity was confined to one locus consisting of five ORFs of which three (ORFA, ORF2 and ORF4) were required for bacteriocin activity. The fifth ORF is predicted to encode an immunity protein to Bcn-A based on in vitro and in vivo assays. The first ORF encodes Bcn-A, a 1,398 amino acid protein, which bioinformatic analysis predicts to be a member of the RHS family of toxins. Based on results of homology modeling, we hypothesize that the amino terminus of Bcn-A interacts with a protein in the outer membrane of X. euvesicatoria. The carboxy terminus of the protein may interact with an as yet unknown protein(s) and puncture the X. euvesicatoria membrane, thereby delivering the accessory proteins into the target and causing cell death. Bcn-A appears to be activated upon secretion based on cell fractionation assays. The other two loci were each shown to be single ORFs encoding Bcn-B and Bcn-C. Both gene products possess homology toward known proteases. Proteinase activity for both Bcn-B and Bcn-C was confirmed using a milk agar assay. Bcn-B is predicted to be an ArgC-like serine protease, which was confirmed by PMSF inhibition of proteolytic activity, whereas Bcn-C has greater than 50% amino acid sequence identity to two zinc metalloproteases.


Assuntos
Proteínas de Bactérias/genética , Bacteriocinas/genética , Loci Gênicos , Lycopersicon esculentum/microbiologia , Doenças das Plantas/microbiologia , Xanthomonas/crescimento & desenvolvimento , Sequência de Aminoácidos , Proteínas de Bactérias/biossíntese , Bacteriocinas/biossíntese , Homologia de Sequência , Xanthomonas/classificação , Xanthomonas/genética , Xanthomonas/metabolismo
3.
PLoS One ; 15(4): e0231975, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32324803

RESUMO

Plantaricin BM-1 is a class IIa bacteriocin with a strong bactericidal effect on gram-positive bacteria. Although plantaricin BM-1 also inhibits the growth of some gram-negative bacteria, including Escherichia coli, the mechanism is not clear. In this study, we used tandem mass tag-based quantitative proteomics analysis to examine the inhibitory mechanism of plantaricin BM-1 against E. coli K12, and evaluated the morphological effects by electron microscopy. The results demonstrated that plantaricin BM-1 inhibits the growth of E. coli K12 by bacteriostatic action, mainly acting on the surface of the cell wall, leading to its collapse. Proteomic analysis identified 976 differentially expressed proteins (>1.2-fold change, p < 0.05) under treatment with plantaricin BM-1, including 490 up-regulated proteins and 486 down-regulated proteins. These proteins were mainly involved in peptidoglycan synthesis and energy metabolism pathways, including amino acid, glyoxylate and dicarboxylate, ABC transporter, and quorum-sensing pathways. Specifically, plantaricin BM-1 treatment significantly improved peptidoglycan synthesis and enhanced the tricarboxylic acid cycle in E. coli K12, and altered the expression of cell membrane proteins. These results provide new insight into the inhibition mechanism of class IIa bacteriocins on gram-negative bacteria, which can lay the foundation for its broader use as an alternative to conventional antibiotics.


Assuntos
Bacteriocinas/farmacologia , Escherichia coli K12/efeitos dos fármacos , Escherichia coli K12/metabolismo , Peptidoglicano/biossíntese , Proteômica , Escherichia coli K12/crescimento & desenvolvimento , Proteínas de Escherichia coli/metabolismo , Proteínas de Membrana/metabolismo
4.
PLoS One ; 15(3): e0229417, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32134941

RESUMO

Streptococcus pneumoniae infections are one of the major causes of morbility and mortality worldwide. Although vaccination and antibiotherapy constitute fundamental and complementary strategies against pneumococcal infections, they present some limitations including the increase in non-vaccine serotypes and the emergence of multidrug-resistances, respectively. Ribosomally-synthesized antimicrobial peptides (i.e. bacteriocins) produced by Lactic Acid Bacteria (LAB) may represent an alternative or complementary strategy to antibiotics for the control of pneumococal infections. We tested the antimicrobial activity of 37 bacteriocinogenic LAB, isolated from food and other sources, against clinical S. pneumoniae strains. Streptococcus infantarius subsp. infantarius LP90, isolated from Venezuelan water-buffalo milk, was selected because of its broad and strong anti-pneumococcal spectrum. The in vitro safety assessment of S. infantarius LP90 revealed that it may be considered avirulent. The analysis of a 19,539-bp cluster showed the presence of 29 putative open reading frames (ORFs), including the genes encoding 8 new class II-bacteriocins, as well as the proteins involved in their secretion, immunity and regulation. Transcriptional analyses evidenced that the induction factor (IF) structural gene, the bacteriocin/IF transporter genes, the bacteriocin structural genes and most of the bacteriocin immunity genes were transcribed. MALDI-TOF analyses of peptides purified using different multichromatographic procedures revealed that the dairy strain S. infantarius LP90 produces at least 6 bacteriocins, including infantaricin A1, a novel anti-pneumococcal two-peptide bacteriocin.


Assuntos
Antibacterianos/metabolismo , Bacteriocinas/genética , Bacteriocinas/metabolismo , Infecções Pneumocócicas/metabolismo , Streptococcus/efeitos dos fármacos , Streptococcus/isolamento & purificação , Sequência de Aminoácidos , Antibacterianos/administração & dosagem , Antibacterianos/isolamento & purificação , Bacteriocinas/administração & dosagem , Bacteriocinas/isolamento & purificação , Humanos , Infecções Pneumocócicas/genética , Infecções Pneumocócicas/microbiologia , Streptococcus/classificação
5.
J Food Sci ; 85(4): 1203-1212, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32118300

RESUMO

Listeria monocytogenes is often responsible for postprocessing contamination of ready-to-eat (RTE) products including cooked ham. As an emerging technology, atmospheric cold plasma (ACP) has the potential to inactivate L. monocytogenes in packaged RTE meats. The objectives of this study were to evaluate the effect of treatment time, modified atmosphere gas compositions (MAP), ham formulation, and post-treatment storage (1 and 7 days at 4 °C) on the reduction of a five-strain cocktail of L. monocytogenes and quality changes in ham subjected to in-package ACP treatment. Initial average cells population on ham surfaces were 8 log CFU/cm2 . The ACP treatment time and gas composition significantly (P < 0.05) influenced the inactivation of L. monocytogenes, irrespective of ham formulations. When MAP1 (20% O2 + 40% CO2 + 40% N2 ) was used, there was a significantly higher log reduction (>2 log reduction) in L. monocytogenes on ham in comparison to MAP2 (50% CO2 + 50% N2 ) and MAP3 (100% CO2 ), irrespective of ham formulation. Addition of preservatives (that is, 0.1% sodium diacetate and 1.4% sodium lactate) or bacteriocins (that is, 0.05% of a partially purified culture ferment from Carnobacterium maltaromaticum UAL 307) did not significantly reduce cell counts of L. monocytogenes after ACP treatment. Regardless of type of ham, storage of 24 hr after ACP treatment significantly reduced cells counts of L. monocytogenes to approximately 4 log CFU/cm2 . Following 7 days of storage after ACP treatment, L. monocytogenes counts were below the detection limit (>6 log reduction) when samples were stored in MAP1. However, there were significant changes in lipid oxidation and color after post-treatment storage. In conclusion, the antimicrobial efficacy of ACP is strongly influenced by gas composition inside the package and post-treatment storage. PRACTICAL APPLICATION: Surface contamination of RTE ham with L. monocytogenes may occur during processing steps such as slicing and packaging. In-package ACP is an emerging nonthermal technology, which can be used as a postpackaging decontamination step in industrial settings. This study demonstrated the influence of in-package gas composition, treatment time, post-treatment storage, and ham formulation on L. monocytogenes inactivation efficacy of ACP. Results of present study will be helpful to optimize in-package ACP treatment and storage conditions to reduce L. monocytogenes, while maintaining the quality of ham.


Assuntos
Embalagem de Alimentos/métodos , Conservação de Alimentos/métodos , Produtos da Carne/microbiologia , Gases em Plasma/farmacologia , Animais , Bacteriocinas/farmacologia , Contagem de Colônia Microbiana , Contaminação de Alimentos/análise , Embalagem de Alimentos/instrumentação , Conservação de Alimentos/instrumentação , Conservantes de Alimentos/farmacologia , Armazenamento de Alimentos , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/crescimento & desenvolvimento , Produtos da Carne/análise , Lactato de Sódio/farmacologia , Suínos
6.
J Phys Chem Lett ; 11(5): 1934-1939, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-32067463

RESUMO

Slow polypeptide conformational changes on time scales of >1 s are generally assumed to be highly cooperative two-state transitions, reflecting the high energy barrier. However, few experimental characterizations have tested the validity of this assumption. We performed residue-specific NMR thermodynamic analysis of the 27-residue lantibiotic peptide, nukacin ISK-1, to characterize the isomerization between two topological states on the second time scale. Unexpectedly, the thermal transition behaviors were distinct among peptide regions, indicating that the topological isomerization process is a mosaic of different degrees of cooperativity. The conformational change path between the two NMR structures was deduced by a targeted molecular dynamics simulation. The unique side-chain threading motions through the monosulfide rings are the structural basis of the high energy barrier, and the nonlocal interactions in the hydrophobic core are the structural basis of the cooperativity. Taken together, we provide an energetic description of the topological isomerization of nukacin ISK-1.


Assuntos
Bacteriocinas/química , Ressonância Magnética Nuclear Biomolecular , Bacteriocinas/metabolismo , Dicroísmo Circular , Isomerismo , Simulação de Dinâmica Molecular , Staphylococcus/metabolismo , Termodinâmica
7.
Int J Food Microbiol ; 322: 108547, 2020 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-32097827

RESUMO

The present study aimed to characterize lactic acid bacteria involved in the different processing steps of tchapalo, a traditional Ivoirian beverage, for their potential application as starter cultures in food and beverages. Lactic acid bacteria (LAB) were therefore isolated and enumerated at different steps of the process on MRS and BEA agars. Of the 465 isolates, 27 produced bacteriocins that inhibit Lactobacillus delbrueckii F/31 strain. Of those, two also inhibited Listeria innocua ATCC 33090, while two others displayed inhibitory activity against L.innocua ATCC 33090, E. faecalis CIP 105042, E. faecalis ATCC 29212, Streptococcus sp. clinical LNSP, E. faecalis CIP 105042 and E. faecium ATCC 51558. The dominant species involved in tchapalo LAB fermentation, as determined by 16S rRNA gene sequencing, were Lactobacillus fermentum (64%), followed by Pediococcus acidilactici (14%). Two strains representing the two dominant species, L. fermentum S6 and P. acidilactici S7, and two potential bacteriocin producers, Weissella confusa AB3E41 and Enterococcus faecium AT1E22, were selected for further characterization. First, genome analysis showed that these strains do not display potential harmful genes such as pathogenic factors or transmissible antibiotic resistance genes. Furthermore, phylogenetic analyses were performed to assess evidence of eventual links to groups of strains with particular properties. They revealed that (i) L. fermentum S6 and P. acidilactici S7 are closely related to strains that ferment plants, (ii) E. faecium AT1E22 belongs to the environmental clade B of E. faecium, while W. confusa is quite similar to other strains also isolated from plant fermentations. Further genome analysis showed that E. faecium AT1E22 contains the Enterocin P gene probably carried by a megaplasmid, whereas no evidence of a bacteriocin gene was found in W. confusa AB3E41. The metabolic and the first step of the probiotic potentials of the different strains were analyzed. Lactobacillus fermentum S6 and P. acidilactici S7 are good candidates to develop starter cultures, and E. faecium AT1E22 should be further tested to confirm its potential as a probiotic strain in the production of sorghum wort.


Assuntos
Cerveja/microbiologia , Lactobacillales/isolamento & purificação , Sorghum/microbiologia , Bacteriocinas/genética , Bacteriocinas/metabolismo , Fermentação , Genoma Bacteriano/genética , Lactobacillales/classificação , Lactobacillales/genética , Lactobacillales/metabolismo , Listeria/crescimento & desenvolvimento , Filogenia , Probióticos/classificação , Probióticos/metabolismo , RNA Ribossômico 16S/genética
8.
Food Chem ; 314: 126244, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31982854

RESUMO

A novel bacteriocin CAMT2, produced by Bacillus amyloliquefaciens ZJHD3-06, has potential as a natural biopreservative for the control of food-borne spoilage and pathogenic bacteria. To avoid interaction of CAMT2 with components of food that may adversely impact its antibacterial activity, CAMT2 was encapsulated into nanovesicles prepared from soybean phosphatidylcholine. The encapsulation of CAMT2 exhibited a limited impact on functional structure and crystallinity of bacteriocin CAMT2, but a high anti-listerial activity in agar, and increase its stability in food at refrigeration temperature (4 °C). The results also showed that both encapsulated and free CAMT2 had good anti-listerial effect in skim milk at refrigeration temperature. However, encapsulated CAMT2 performed better than free CAMT2 against Listeria in whole milk. These results showed that nano-encapsulation is an effective method of protecting bacteriocin from fat in milk and retaining its antimicrobial efficacy.


Assuntos
Bacillus amyloliquefaciens/química , Bacteriocinas/farmacologia , Listeria monocytogenes/efeitos dos fármacos , Leite/microbiologia , Nanoestruturas/química , Animais , Fosfatidilcolinas
9.
Microb Cell Fact ; 19(1): 5, 2020 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-31918711

RESUMO

BACKGROUND: Heterologous expression of secondary metabolite gene clusters is used to achieve increased production of desired compounds, activate cryptic gene clusters, manipulate clusters from genetically unamenable strains, obtain natural products from uncultivable species, create new unnatural pathways, etc. Several Streptomyces species are genetically engineered for use as hosts for heterologous expression of gene clusters. S. lividans TK24 is one of the most studied and genetically tractable actinobacteria, which remain untapped. It was therefore important to generate S. lividans chassis strains with clean metabolic backgrounds. RESULTS: In this study, we generated a set of S. lividans chassis strains by deleting endogenous gene clusters and introducing additional φC31 attB loci for site-specific integration of foreign DNA. In addition to the simplified metabolic background, the engineered S. lividans strains had better growth characteristics than the parental strain in liquid production medium. The utility of the developed strains was validated by expressing four secondary metabolite gene clusters responsible for the production of different classes of natural products. Engineered strains were found to be superior to the parental strain in production of heterologous natural products. Furthermore, S. lividans-based strains were better producers of amino acid-based natural products than other tested common hosts. Expression of a Streptomyces albus subsp. chlorinus NRRL B-24108 genomic library in the modified S. lividans ΔYA9 and S. albus Del14 strains resulted in the production of 7 potentially new compounds, only one of which was produced in both strains. CONCLUSION: The constructed S. lividans-based strains are a great complement to the panel of heterologous hosts for actinobacterial secondary metabolite gene expression. The expansion of the number of such engineered strains will contribute to an increased success rate in isolation of new natural products originating from the expression of genomic and metagenomic libraries, thus raising the chance to obtain novel biologically active compounds.


Assuntos
Antibacterianos/biossíntese , Produtos Biológicos , Metabolismo Secundário/genética , Streptomyces lividans/genética , Actinobacteria/genética , Actinobacteria/metabolismo , Antibacterianos/química , Bacteriocinas/biossíntese , Bacteriocinas/química , Produtos Biológicos/química , Produtos Biológicos/metabolismo , Clonagem Molecular , Engenharia Genética/métodos , Família Multigênica , Peptídeos Cíclicos/biossíntese , Peptídeos Cíclicos/química , Streptomyces lividans/metabolismo , Tunicamicina/biossíntese , Tunicamicina/química
10.
FASEB J ; 34(1): 1018-1037, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31914603

RESUMO

Recombinant antimicrobial peptide microcin J25 (MccJ25) causes potent antimicrobial activity against enterotoxigenic Escherichia coli (ETEC) in vitro; however, independently of this activity, its role in suppressing intestinal inflammation and epithelial barrier injury in vivo remains unclear. We investigated the therapeutic effects of MccJ25 on intestinal inflammation and epithelial barrier dysfunction and the underlying mechanism, using gentamicin for comparison. In a mouse model of intestinal inflammation, therapeutic administration of either MccJ25 or gentamicin after ETEC K88 infection attenuated clinical symptoms, reduced intestinal pathogen colonization, improved intestinal morphology, and decreased inflammatory pathologies and intestinal permeability, ultimately improving the hosts' health. MccJ25 also attenuated ETEC-induced mouse intestinal barrier dysfunction by enhancing tight junction proteins (TJPs). Using the human epithelial cell line Caco-2, we verified the epithelial barrier-strengthening and mucosal injury-alleviating effects of MccJ25 on ETEC infection: increased expression of TJPs by activating the p38/MAPK pathway, balancing the microbiota, and improving short-chain fatty acid concentrations in the cecum of ETEC-infected mice. Although gentamicin and MccJ25 had similar effects in the inflamed gut, MccJ25 was superior to gentamicin with regard to defending the host from ETEC infection. Overall, MccJ25 may be a promising therapeutic drug for treating enteric pathogen-induced intestinal inflammation diseases.


Assuntos
Peptídeos Catiônicos Antimicrobianos/farmacologia , Bacteriocinas/farmacologia , Epitélio/efeitos dos fármacos , Infecções por Escherichia coli/imunologia , Inflamação/imunologia , Mucosa Intestinal/efeitos dos fármacos , Animais , Antibacterianos/farmacologia , Células CACO-2 , Citocinas/metabolismo , Escherichia coli Enterotoxigênica , Feminino , Microbioma Gastrointestinal , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Proteínas Recombinantes/farmacologia
11.
BMC Cancer ; 20(1): 39, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31948419

RESUMO

BACKGROUND: Optimal therapy for colorectal carcinoma (CRC), a frequently diagnosed malignancy, does not exist. Some of colicins and microcins, ribosomally synthesized peptides by gramnegative bacteria, have shown significant biological activity specifically against different cancer cells in vitro and in vivo conditions. The aim of this prospective study was to evaluate natural colicin and microcin production by large intestinal mucosal bacteria in each stage of colorectal neoplasia and in those with a history of colorectal neoplasia. METHODS: A total of 21 patients with non-advanced adenoma (non-a-A; 16/21 with current and 5/21 with history of non-a-A), 20 patients with advanced colorectal adenoma (a-A; 11/20 with current and 9/20 with history of a-A), 22 individuals with CRC (9/22 with current and 13/22 with history of CRC) and 20 controls were enrolled. Mucosal biopsies from the caecum, transverse colon and the rectum were taken during colonoscopy in each individual. Microbiological culture followed. Production of colicins and microcins was evaluated by PCR methods. RESULTS: A total of 239 mucosal biopsies were taken. Production of colicins and microcins was significantly more frequent in individuals with non-a-A, a-A and CRC compared to controls. No significant difference in colicin and microcin production was found between patients with current and previous non-a-A, a-A and CRC. Significantly more frequent production of colicins was observed in men compared to women at the stage of colorectal carcinoma. A later onset of increased production of microcins during the adenoma-carcinoma sequence has been observed in males compared to females. CONCLUSIONS: Strains isolated from large intestinal mucosa in patients with colorectal neoplasia produce colicins and microcins more frequently compared to controls. Bacteriocin production does not differ between patients with current and previous colorectal neoplasia. Fundamental differences in bacteriocin production have been confirmed between males and females.


Assuntos
Bactérias/metabolismo , Bacteriocinas/biossíntese , Neoplasias Colorretais/patologia , Microbioma Gastrointestinal , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiologia , Biópsia , Feminino , Humanos , Masculino
12.
Curr Opin Biotechnol ; 61: 160-167, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31968296

RESUMO

Bacteriocins are natural antimicrobials that have been consumed via fermented foods for millennia and have been the focus of renewed efforts to identify novel bacteriocins, and their producing microorganisms, for use as food biopreservatives and other applications. Bioengineering bacteriocins or combining bacteriocins with multiple modes of action (hurdle approach) can enhance their preservative effect and reduces the incidence of antimicrobial resistance. In addition to their role as food biopreservatives, bacteriocins are gaining credibility as health modulators, due to their ability to regulate the gut microbiota, which is strongly associated with human wellbeing. Indeed the strengthening link between the gut microbiota and obesity make bacteriocins ideal alternatives to Animal Growth Promoters (AGP) in animal feed also. Here we review recent advances in bacteriocin research that will contribute to the development of functional foods and feeds as a consequence of roles in food biopreservation and human/animal health.


Assuntos
Anti-Infecciosos , Bacteriocinas , Animais , Antibacterianos , Microbiologia de Alimentos , Conservação de Alimentos , Humanos
13.
Microbiol Res ; 231: 126374, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31756597

RESUMO

The ability to produce plethora of secondary metabolites and enzymes for pharmaceutical, agricultural and biotechnological applications make actinobacteria one of the most explored microbes among prokaryotes. The secondary metabolites and lytic enzymes of actinobacteria are known for their role in various physiological, cellular and biological processes including environmental sensing, mineral acquisition and recycling, and establishing social communication. In addition, the basic scaffold of secondary metabolties derived from actinobacteria is a source of inspiration for chemists. Recent development in "gene to metabolites" and "metabolites to gene" based omics technologies have played major role in revealing the prevalence of silent gene clusters in the genome of actinobacteria. Moreover, the development in precision-based genome editing tools and use of artificial gene operon for pathway engineering have emerged as a key player in activation of these silent/cryptic gene clusters for novel metabolites at large scale which were previously found to be poorly expressed and difficult to characterize in lab conditions. The access to diverse uncharacterized biosynthetic gene clusters of different types and the leverage of modern gene editing tools for modulated expression of the operons would contribute to novel product discovery and product diversification compared to traditional way of mining metabolites. Here, in review article, we have discussed the taxonomic status, genomic potential of actinobacteria for various secondary metabolites and role of genetic engineering to explore these microbes for human welfare.


Assuntos
Actinobacteria , Vias Biossintéticas/genética , Biotecnologia , Interações entre Hospedeiro e Microrganismos/genética , Metabolismo Secundário/genética , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/metabolismo , Anti-Infecciosos , Antibiose , Bacteriocinas/biossíntese , Engenharia Genética , Genoma Bacteriano , Genômica , Humanos , Metaboloma , Metabolômica , Percepção de Quorum , Sideróforos/metabolismo , Compostos Orgânicos Voláteis/metabolismo
14.
Arch Microbiol ; 202(4): 755-763, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31807807

RESUMO

Thuricin 4AJ1, produced by Bacillus thuringiensis strain 4AJ1, showed inhibition activity against Bacillus cereus 0938 and ATCC 10987. It began to appear in the stationary phase and reached its maximum activity level of 209.958 U at 18 h against B. cereus 0938 and 285.689 U at 24 h against B. cereus ATCC 10987. Tricine-SDS-PAGE results showed that the partly purified thuricin 4AJ1 was about 6.5 kDa. The molecular weights of the known B. thuringiensis bacteriocins and the ones obtained by the two mainstream websites for predicting bacteriocins were inconsistent with the size of the thuricin 4AJ1, indicating that the bacteriocin obtained in this study may have a novel structure. Based on the biochemical properties, the thuricin 4AJ1 activities increased after treatment with proteinase K and lipase II, and were not affected by a-amylase, catalase, α-chymotrypsin VII and α-chymotrypsin II. It was heat tolerant, being active up to 90º C. In the pH 3-10 range, it maintained most of its activity. Finally, the sensitivity of the strain 4AJ1 to commonly used antibiotics was tested. In view of its stability and antibacterial activity, thuricin 4AJ1 may be applied as a food biopreservative.


Assuntos
Bacillus thuringiensis/metabolismo , Bacteriocinas/isolamento & purificação , Antibacterianos/farmacologia , Bacillus cereus/efeitos dos fármacos , Bacillus thuringiensis/química , Bacteriocinas/química , Bacteriocinas/farmacologia , Eletroforese em Gel de Poliacrilamida , Microbiologia de Alimentos , Peso Molecular
15.
Biochim Biophys Acta Biomembr ; 1862(2): 183135, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31738901

RESUMO

The mechanism of action of the anti-Listeria peptide enterocin CRL35 was studied with biophysical tools by using lipid mixtures that mimicked Gram-positive plasma membranes. Langmuir monolayers and infrared spectroscopy indicated that the peptide readily interacted with phospholipid assembled in monolayers and bilayers to produce a dual effect, depending on the acyl chains. Indeed, short chain mixtures were disordered by enterocin CRL35, but the gel-phases of membranes composed by longer acyl chains were clearly stabilized by the bacteriocin. Structural and functional studies indicated that non-bilayer states were formed when liposomes were co-incubated with enterocin CRL35, whereas significant permeabilization could be detected when bilayer and non-bilayer states co-existed. Results can be explained by a two-step model in which the N-terminal of the peptide firstly docks enterocin CRL35 on the lipid surface by means of electrostatic interactions; then, C-terminal triggers membrane perturbation by insertion of hydrophobic α-helix.


Assuntos
Bacteriocinas/química , Lipídeos de Membrana/química , Bacteriocinas/metabolismo , Permeabilidade da Membrana Celular , Bicamadas Lipídicas/química , Fluidez de Membrana , Lipídeos de Membrana/metabolismo , Ligação Proteica
16.
J Appl Microbiol ; 128(2): 458-472, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31623015

RESUMO

AIMS: We aimed to evaluate some specific conditions for growth of Pediococcus pentosaceus ST65ACC and its bacteriocin expression through ABC transporters; to purify the bacteriocin and determine its sequence; and to evaluate the cytotoxicity potential of the purified bacteriocin(s). METHODS AND RESULTS: The results presented for growth behaviour of P. pentosaceus ST65ACC showed that the bacterial growth was slightly influenced when cultured in MRS broth with different amounts of inoculum: 1, 2, 5 and 10%. The bacteriocin activity increased when 5 and 10% inocula were used. The carbon source (glucose) used in different amounts (1, 2, 3 or 4%) had no significant effect on growth and bacteriocin production. The studied strain P. pentosaceus ST65ACC was able to metabolize xylooligosaccharide (XOS) as the sole carbon source, resulting in the production of an antimicrobial peptide. The genes involved in the ABC transport system and sugar metabolism of P. pentosaceus ST65ACC were expressed at different levels. The bacteriocin produced by P. pentosaceus ST65ACC was partially purified by precipitation with ammonium sulphate (40% saturation), followed by reversed-phase liquid chromatography, resulting in the identification of an active bacteriocin. Tandem mass spectrometry was used to identify the partial sequence KYYGNGVTCGKHSCSVDWGK sharing high similarity to coagulin A. The semi-purified bacteriocin had low cytotoxicity based on estimated values for maximal nontoxic concentration (MNC) and cytotoxicity concentration (CC50 ). CONCLUSIONS: The bacteriocin produced by P. pentosaceus ST65ACC is similar to coagulin, with low cytotoxicity, strong antimicrobial activity and possible additional metabolite routes in the producer cell. In addition to MRS broth, bacteriocin was produced also in medium containing XOS (as the single carbon source). SIGNIFICANCE AND IMPACT OF THE STUDY: To the best of our knowledge, this is the first report of evaluation of the role of ABC transporters in the expression of bacteriocin by P. pentosaceus, cultured in MRS and XOS.


Assuntos
Bacteriocinas/genética , Queijo/microbiologia , Leite/microbiologia , Pediococcus pentosaceus/metabolismo , Animais , Antibacterianos/química , Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Bacteriocinas/biossíntese , Bacteriocinas/isolamento & purificação , Bacteriocinas/farmacologia , Expressão Gênica , Concentração de Íons de Hidrogênio , Pediococcus pentosaceus/química , Pediococcus pentosaceus/genética , Pediococcus pentosaceus/crescimento & desenvolvimento
17.
J Dairy Sci ; 103(2): 1223-1237, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31759592

RESUMO

Raw milk contains wide microbial diversity, composed mainly of lactic acid bacteria (LAB), which are used as probiotics in both human and animal husbandry. We isolated, characterized, and evaluated LAB from indigenous Bangladeshi raw milk to assess probiotic potential, including antagonistic activity (against Escherichia coli O157: H7, Enterococcus faecalis, Salmonella Typhimurium, Salmonella Enteritidis, and Listeria monocytogenes), survivability in simulated gastric juice, tolerance to phenol and bile salts, adhesion to ileum epithelial cells, auto- and co-aggregation, hydrophobicity, α-glucosidase inhibitory activity, and antibiotic susceptibility tests. The 4 most promising LAB strains showed probiotic potential and were identified as Lactobacillus casei, Lactobacillus plantarum (which produced plantaricin EF), Lactobacillus fermentum, and Lactobacillus paracasei. These strains inhibited all pathogens tested at various degrees, and competitively excluded pathogens with viable counts of 3.0 to 6.0 log cfu/mL. Bacteriocin, organic acids, and low-molecular-weight substances were mainly responsible for antimicrobial activity by the LAB strains. All 4 LAB strains were resistant to oxacillin and 3 were resistant to vancomycin and streptomycin, with multiple antibiotic resistance indices >0.2. After further in vivo evaluation, these LAB strains could be considered probiotic candidates with application in the food industry.


Assuntos
Lactobacillales/fisiologia , Leite/microbiologia , Probióticos , Animais , Bacteriocinas/metabolismo , Bovinos , Enterococcus faecalis/isolamento & purificação , Enterococcus faecalis/fisiologia , Feminino , Suco Gástrico/microbiologia , Cabras , Humanos , Lactobacillales/isolamento & purificação , Lactobacillus casei/isolamento & purificação , Lactobacillus casei/fisiologia , Lactobacillus fermentum/isolamento & purificação , Lactobacillus fermentum/fisiologia , Lactobacillus plantarum/isolamento & purificação , Lactobacillus plantarum/fisiologia , Probióticos/farmacologia
18.
Meat Sci ; 159: 107917, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31494521

RESUMO

In this study, effects of ingoing nitrite level (0, 50, 100 and 150 mg/kg), use of sodium ascorbate, addition of starter culture (Lactobacillus plantarum GM77 + Staphylococcus xylosus GM92) and cooking level (control, medium, medium well, well done and very well done) on nitrosamine formation in heat-treated sucuk, a type of semi-dry fermented sausage, were investigated. The use of ascorbate had no significant effect on NDMA (N-Nitrosodimethylamine) and NPIP (N-Nitrosopiperidine) contents in the presence of starter culture. A higher NPYR (N- Nitrosopyrrolidine) content was detected in the group with starter culture at 150 mg/kg nitrite level in comparison to the group without starter culture. Cooking level affected all identified nitrosamines very significantly. Ingoing nitrite level × cooking level interaction was only effective on NPIP and advanced cooking levels (well done and very well done) at higher ingoing nitrite levels (100 and 150 mg/kg) resulted in significant increases in NPIP content.


Assuntos
Ácido Ascórbico/química , Culinária , Dimetilnitrosamina/química , Produtos da Carne/análise , Nitritos/química , Animais , Bacteriocinas , Bovinos , Microbiologia de Alimentos , Temperatura Alta , Fosfatos de Inositol , Lactobacillus plantarum/metabolismo , Produtos da Carne/microbiologia , Carne Vermelha , Staphylococcus/metabolismo
19.
Int J Food Microbiol ; 313: 108390, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31678818

RESUMO

Growth of L. monocytogenes is among the most important factors affecting the risk of human listeriosis. In ready to eat leafy greens, the use of anti-Listeria treatments represents a good alternative to inhibit growth during storage. Several commercially available antimicrobial agents have been suggested as effective intervention strategies. Among them, phage preparations and bacteriocin-producing strains have shown promising results against L. monocytogenes. In this study, we investigate the efficacy of two commercially available surface treatments, the bacteriophage formulation PhageGuard Listex (Micreos Food Safety B.V., NL) and the bacteriocin-producing culture SafePro® (CHR Hansen, DK) to inactivate L. monocytogenes in fresh-cut curly endive after processing and during storage. Fresh-cut endive was inoculated with a cold-adapted L. monocytogenes cocktail of 6 strains (4.4 ±â€¯0.0 log cfu/g) and treated with the anti-Listeria treatments. The treatments were applied using a spray system at two different places within the processing line, on the conveyor belt and in the centrifuge. A total of 5 different treatments were applied: i) Untreated (CT); ii) PhageGuard Listex on the conveyor belt (Listex_Conveyor); iii) PhageGuard Listex during centrifugation (Listex_Centrifuge); iv) SafePro on the conveyor belt (SafePro_Conveyor); and v) SafePro during centrifugation (SafePro_Centrifuge). Samples were stored 3 days at 5 °C plus 5 days at 8 °C. PhageGuard Listex treatment reduced L. monocytogenes in fresh-cut endive by 2.5 logs, regardless of the place of treatment application (conveyor belt or centrifuge). On the other hand, SafePro only reduced L. monocytogenes by 0.2 and 0.4 logs, at the conveyor belt and centrifuge, respectively. Maximum L. monocytogenes reductions of about 3.5 log units were observed in fresh-cut endive treated with PhageGuard Listex after 3 days of storage. At the end of the shelf life (8 days), the initial trends were maintained and the fresh-cut curly endive treated with PhageGuard Listex showed the lowest L. monocytogenes concentration. However, by the end of the shelf-life, L. monocytogenes showed higher levels (1.3-fold) than immediately after the application of the treatment. One hypothesis could be that L. monocytogenes cells, which were able to survive the anti-Listeria treatments, were also able to proliferate under the specific storage conditions. Based on the obtained results, PhageGuard Listex seems to be a promising decontamination agent for leafy greens aiming to reduce growth of the bacteria but further work is needed.


Assuntos
Conservação de Alimentos/métodos , Listeria monocytogenes/crescimento & desenvolvimento , Verduras/microbiologia , Bacteriocinas/metabolismo , Bacteriófagos/fisiologia , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Conservação de Alimentos/instrumentação , Inocuidade dos Alimentos , Humanos , Listeria monocytogenes/metabolismo , Listeria monocytogenes/virologia , Projetos Piloto , Folhas de Planta/microbiologia , Temperatura
20.
Colloids Surf B Biointerfaces ; 185: 110595, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31735419

RESUMO

The interaction between the cinnamycin and the biomimetic membranes was studied using the atomic force microscope(AFM). The bilayer was composed of the monolayer tethered on the gold surface and the outer layer fused with the vesicles on the monolayer. The vesicles were prepared at the desired ratio of dioleoylphosphatidylethanolamine(DOPE) to dioleoylphosphatidylcholine(DOPC). On the bilayer, the surface force measurement was performed with the cinnamycin immobilized covalently on the tip surface. The immobilization led to the presence of the adhesion, which was found while the tip was retracted from the bilayer. In addition, the magnitude of the adhesive force was changed with respect to the composition of DOPE in the outer layer. The difference in the adhesion may be attributed to the mean-molecular-area of DOPE and the specific-binding density on the outer layer. Furthermore, the analysis of the rupture force with respect to the loading rate indicated that the rupture length was around 0.1∼0.13 nm, which was similar to that of a van der Waals bond.


Assuntos
Bacteriocinas/química , Materiais Biomiméticos/química , Bicamadas Lipídicas/química , Membranas Artificiais , Peptídeos Cíclicos/química , Fosfatidilcolinas/química , Fosfatidiletanolaminas/química , Bacteriocinas/metabolismo , Materiais Biomiméticos/metabolismo , Bicamadas Lipídicas/metabolismo , Peptídeos Cíclicos/metabolismo , Fosfatidilcolinas/metabolismo , Fosfatidiletanolaminas/metabolismo
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