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1.
Nature ; 582(7811): 294-297, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32523118

RESUMO

The primary structural component of the bacterial cell wall is peptidoglycan, which is essential for viability and the synthesis of which is the target for crucial antibiotics1,2. Peptidoglycan is a single macromolecule made of glycan chains crosslinked by peptide side branches that surrounds the cell, acting as a constraint to internal turgor1,3. In Gram-positive bacteria, peptidoglycan is tens of nanometres thick, generally portrayed as a homogeneous structure that provides mechanical strength4-6. Here we applied atomic force microscopy7-12 to interrogate the morphologically distinct Staphylococcus aureus and Bacillus subtilis species, using live cells and purified peptidoglycan. The mature surface of live cells is characterized by a landscape of large (up to 60 nm in diameter), deep (up to 23 nm) pores constituting a disordered gel of peptidoglycan. The inner peptidoglycan surface, consisting of more nascent material, is much denser, with glycan strand spacing typically less than 7 nm. The inner surface architecture is location dependent; the cylinder of B. subtilis has dense circumferential orientation, while in S. aureus and division septa for both species, peptidoglycan is dense but randomly oriented. Revealing the molecular architecture of the cell envelope frames our understanding of its mechanical properties and role as the environmental interface13,14, providing information complementary to traditional structural biology approaches.


Assuntos
Bacillus subtilis/citologia , Bacillus subtilis/ultraestrutura , Parede Celular/química , Parede Celular/ultraestrutura , Microscopia de Força Atômica , Staphylococcus aureus/citologia , Staphylococcus aureus/ultraestrutura , Bacillus subtilis/química , Viabilidade Microbiana , Peptidoglicano/química , Peptidoglicano/isolamento & purificação , Peptidoglicano/ultraestrutura , Staphylococcus aureus/química
2.
Ecotoxicol Environ Saf ; 199: 110750, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32446103

RESUMO

Both antibiotics and surfactants commonly exist in natural environment and have generated great concerns due to their biological influence on the ecosystem. A major concern lies in the capacity of antibiotics to induce bacterial filaments formation, which has potential health risks. However, their joint effect is not clear so far. Here, we studied the joint effect of cephalexin (Cex), a typical antibiotic, and differently charged surfactants on the formation of E. coli filaments. Three kinds of surfactants characterized by different charges were used: cationic surfactant (CTAB), anionic surfactant (SDS) and nonionic surfactant (Tween). Data showed that Cex alone caused the formation of E. coli filaments, elongating their maximum profile from ca. 2 µm (a single E. coli cell) to tens of micrometers (an E. coli filament). A joint use of surfactants with Cex could produce even longer E. coli filaments, elongating the maximum length of the bacteria to larger than 100 µm. The capacity order of different surfactants under their optimum concentrations to produce elongated E. coli filaments was Tween > SDS > CTAB. The E. coli filaments were characterized with a normal DNA distribution and a good cell membrane integrity. We measured the stiffness of bacterial cell wall by atomic force microscopy and correlated the elongation capacity of the E. coli filaments to the stiffness of cell wall. Zeta potential measurement indicated that inserting into or being bound to the cell surface in a large quantity was tested not to be the major way that surfactants interacted with bacteria.


Assuntos
Antibacterianos/toxicidade , Cefalexina/toxicidade , Poluentes Ambientais/toxicidade , Escherichia coli/efeitos dos fármacos , Polissorbatos/toxicidade , Tensoativos/toxicidade , Parede Celular/efeitos dos fármacos , Parede Celular/ultraestrutura , Sinergismo Farmacológico , Ecossistema , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/ultraestrutura
3.
PLoS One ; 15(5): e0227591, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32433654

RESUMO

Plants emit high rates of methanol (meOH), generally assumed to derive from pectin demethylation, and this increases during abiotic stress. In contrast, less is known about the emission and source of acetic acid (AA). In this study, Populus trichocarpa (California poplar) leaves in different developmental stages were desiccated and quantified for total meOH and AA emissions together with bulk cell wall acetylation and methylation content. While young leaves showed high emissions of meOH (140 µmol m-2) and AA (42 µmol m-2), emissions were reduced in mature (meOH: 69%, AA: 60%) and old (meOH: 83%, AA: 76%) leaves. In contrast, the ratio of AA/meOH emissions increased with leaf development (young: 35%, mature: 43%, old: 82%), mimicking the pattern of O-acetyl/methyl ester ratios of leaf bulk cell walls (young: 35%, mature: 38%, old: 51%), which is driven by an increase in O-acetyl and decrease in methyl ester content with age. The results are consistent with meOH and AA emission sources from cell wall de-esterification, with young expanding tissues producing highly methylated pectin that is progressively demethyl-esterified. We highlight the quantification of AA/meOH emission ratios as a potential tool for rapid phenotype screening of structural carbohydrate esterification patterns.


Assuntos
Ácido Acético/metabolismo , Parede Celular/metabolismo , Metanol/metabolismo , Folhas de Planta/metabolismo , Acetilação , Atmosfera , Hidrolases de Éster Carboxílico/metabolismo , Esterificação , Metilação , Pectinas/metabolismo , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/genética , Populus/efeitos dos fármacos , Populus/crescimento & desenvolvimento , Populus/metabolismo , Estresse Fisiológico/genética
4.
Ecotoxicol Environ Saf ; 200: 110748, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32470678

RESUMO

Cadmium (Cd) is an inauspicious abiotic traction that not only influences crop productivity and its growth parameters, but also has adverse effects on human health if these crops are consumed. Among crops, leafy vegetables which are the good source of mineral and vitamins accumulate more Cd than other vegetables. It is thus important to study photosynthetic variables, amino acid composition, and ultrastructural localization of Cd differences in response to Cd accumulation between two low and high Cd accumulating Brassica rapa ssp. chinensis L. (pak choi) cultivars, differing in Cd accumulation ability. Elevated Cd concentrations significantly lowered plant growth rate, biomass, leaf gas exchange and concentrations of amino acids collated to respective controls of both cultivars. Electron microscopy indicated that the impact of high Cd level on ultrastructure of leaf cells was associated to affecting cell functionalities, i.e. irregular cell wall, withdrawal of cell membrane, and chloroplast structure which has negative impact on photosynthetic activities, thus causing considerable plant growth suppression. Damage in root cells were observed in the form of enlargement of vacuole. The energy dispersive micro X-ray spectroscopy of both cultivars leaves indicated that cellular structure exhibited exudates of Cd-dense material. Ultrastructural damages and phytotoxicity were more pronounced in high accumulator cultivar as compared to the low accumulator cultivar. These findings are useful in determining the mechanisms of differential Cd-tolerance among cultivars with different Cd tolerance abilities at cellular level.


Assuntos
Brassica rapa/efeitos dos fármacos , Brassica rapa/metabolismo , Cádmio/toxicidade , Aminoácidos/análise , Biomassa , Brassica rapa/crescimento & desenvolvimento , Brassica rapa/ultraestrutura , Cádmio/farmacocinética , Parede Celular/efeitos dos fármacos , Parede Celular/ultraestrutura , Produtos Agrícolas/efeitos dos fármacos , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/metabolismo , Humanos , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Folhas de Planta/ultraestrutura
5.
PLoS One ; 15(5): e0231881, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32357186

RESUMO

The sequencing and bioinformatics analysis of bacteriophages infecting mycobacteria has yielded a large amount of information on their evolution, including that on their environmental propagation on other genera such as Gordonia, closely related to Mycobacterium. However, little is known on mycobacteriophages cell biology such as the nature of their receptor(s) or their replication cycle. As part of our on-going screening for novel mycobacteriophages, we herein report the isolation and genome bioinformatics analysis of Weirdo19ES, a singleton Siphoviridae temperate mycobacteriophage with a 70.19% GC content. Nucleotide and protein sequence comparison to actinobacteriophage databases revealed that Weirdo19ES shows low homology to Gordonia phage Ruthy and mycobacteriophages falling in clusters Q and G and to singleton DS6A.Weirdo19ES also displays uncommon features such as a very short Lysin A gene (with only one enzymatic domain) and two putative HNH endonucleases. Mycobacterium smegmatis mutants resistant to Weirdo19ES are cross- resistant to I3. In agreement with that phenotype, analysis of cell envelope of those mutants showed that Weirdo19ES shares receptors with the transducing mycobacteriophage I3.This singleton mycobacteriophage adds up to the uncommonness of local mycobacteriophages previously isolated by our group and helps understanding the nature of mycobacteriophage receptors.


Assuntos
Genoma Viral , Glicolipídeos/genética , Micobacteriófagos/genética , Mycobacterium smegmatis/virologia , Composição de Bases , Parede Celular/metabolismo , Análise por Conglomerados , Uso do Códon , Hibridização Genômica Comparativa , Glicolipídeos/deficiência , Micobacteriófagos/classificação , Micobacteriófagos/isolamento & purificação , Mycobacterium smegmatis/genética , Mycobacterium smegmatis/isolamento & purificação , Fenótipo , Filogenia
6.
PLoS One ; 15(5): e0227396, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32469865

RESUMO

Elsinoë fawcettii, a necrotrophic fungal pathogen, causes citrus scab on numerous citrus varieties around the world. Known pathotypes of E. fawcettii are based on host range; additionally, cryptic pathotypes have been reported and more novel pathotypes are thought to exist. E. fawcettii produces elsinochrome, a non-host selective toxin which contributes to virulence. However, the mechanisms involved in potential pathogen-host interactions occurring prior to the production of elsinochrome are unknown, yet the host-specificity observed among pathotypes suggests a reliance upon such mechanisms. In this study we have generated a whole genome sequencing project for E. fawcettii, producing an annotated draft assembly 26.01 Mb in size, with 10,080 predicted gene models and low (0.37%) coverage of transposable elements. A small proportion of the assembly showed evidence of AT-rich regions, potentially indicating genomic regions with increased plasticity. Using a variety of computational tools, we mined the E. fawcettii genome for potential virulence genes as candidates for future investigation. A total of 1,280 secreted proteins and 276 candidate effectors were predicted and compared to those of other necrotrophic (Botrytis cinerea, Parastagonospora nodorum, Pyrenophora tritici-repentis, Sclerotinia sclerotiorum and Zymoseptoria tritici), hemibiotrophic (Leptosphaeria maculans, Magnaporthe oryzae, Rhynchosporium commune and Verticillium dahliae) and biotrophic (Ustilago maydis) plant pathogens. Genomic and proteomic features of known fungal effectors were analysed and used to guide the prioritisation of 120 candidate effectors of E. fawcettii. Additionally, 378 carbohydrate-active enzymes were predicted and analysed for likely secretion and sequence similarity with known virulence genes. Furthermore, secondary metabolite prediction indicated nine additional genes potentially involved in the elsinochrome biosynthesis gene cluster than previously described. A further 21 secondary metabolite clusters were predicted, some with similarity to known toxin producing gene clusters. The candidate virulence genes predicted in this study provide a comprehensive resource for future experimental investigation into the pathogenesis of E. fawcettii.


Assuntos
Ascomicetos/genética , Citrus/microbiologia , Genoma Fúngico/genética , Anotação de Sequência Molecular , Ascomicetos/patogenicidade , Parede Celular/enzimologia , Mineração de Dados , Família Multigênica/genética , Metabolismo Secundário/genética
7.
Int J Syst Evol Microbiol ; 70(5): 3139-3144, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32375934

RESUMO

A Gram-stain-positive, non-flagellated, non-gliding, coccoid bacterial strain, designated JLT9T, was isolated from the shallow-sea hydrothermal system off Kueishantao Island, Taiwan, ROC. Strain JLT9T was aerobic, chemoheterotrophic and grew optimally at 35 °C, at pH 6.0 and in the presence of 2.5 % (w/v) NaCl. Strain JLT9T exhibited highest 16S rRNA gene sequence similarity to Serinicoccus marinus DSM 15273T (98.83 %). Phylogenetic trees based on 16S rRNA gene sequences revealed that strain JLT9T belonged to the genus Serinicoccus, clustering with Serinicoccus marinus JC1078T, Serinicoccus profundi MCCC 1A05965T, Serinicoccus sediminis GP-T3-3T and Serinicoccus chungangensis CAU9536T. The digital DNA-DNA genome hybridization values between strain JLT9T and the closest related strain S. marinus DSM 15273T was 34.30 %. The DNA G+C content was 72.43 mol%. The dominant fatty acids were identified as iso-C15 : 0 (41.4 %) and iso-C16 : 0 (24.7 %). The polar lipids of strain JLT9T comprised diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol, three unidentified glycolipid and an unidentified phospholipid. The predominant isoprenoid quinone was MK-8 (H4). The cell wall contained ornithine and serine, and no diaminopimelic acid. On the basis of phylogenetic data and several distinct phenotypic characteristics, strain JLT9T represents a novel species of the genus Serinicoccus, for which the name Serinicoccus hydrothermalis sp. nov. is proposed. The type strain is JLT9T (=CGMCC 1.15779T=JCM 31502T).


Assuntos
Actinomycetales/classificação , Fontes Hidrotermais/microbiologia , Filogenia , Água do Mar/microbiologia , Actinomycetales/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , Parede Celular/química , DNA Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Graxos/química , Glicolipídeos/química , Ilhas , Hibridização de Ácido Nucleico , Peptidoglicano/química , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Taiwan , Vitamina K 2/análogos & derivados , Vitamina K 2/química
8.
Int J Syst Evol Microbiol ; 70(5): 3340-3347, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32375935

RESUMO

A novel Gram-stain-positive, actinobacterial strain, designated C5-26T, was isolated from soil from a natural cave in Jeju, Republic of Korea, and its taxonomic position was investigated using a polyphasic approach. The organism was aerobic, and cells were non-spore-forming, non-motile cocci that occurred singly, in pairs, in triplets, in tetrads, in short chains or in irregular clusters. Colonies of the cells were circular, convex, entire and white. The peptidoglycan type was A4α with an l-Ser-d-Asp interpeptide bridge. The whole-cell sugars comprised glucose, rhamnose, mannose, arabinose, galactose and ribose. The major menaquinone was MK-8(H4). The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and an unidentified phospholipid. The major fatty acids were iso-C16 : 0 and iso-C16 : 1 h. The size of the draft genome was 5.32 Mbp with depth of coverage of 161×. The G+C content of the genomic DNA was 67.1 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that the novel isolate belonged to the family Dermacoccaceae and formed a distinct subcluster at the base of the radiation of the genus Luteipulveratus. Highest sequence similarities of the novel isolate were found to the type strains of Luteipulveratus halotolerans (96.2 %), Branchiibius hedensis (95.4 %), Luteipulveratus mongoliensis (95.4 %) and Branchiibius cervicis (95.3 %). The whole genome-based phylogeny supported the novelty of the isolate at the genus level in the family Dermacoccaceae. On the basis of data from this polyphasic study, strain C5-26T (=KCTC 39632T=DSM 108676T) represents a novel species of a new genus in the family Dermacoccaceae, for which the name Leekyejoonella antrihumi gen. nov., sp. nov. is proposed.


Assuntos
Actinobacteria/classificação , Cavernas/microbiologia , Filogenia , Microbiologia do Solo , Actinobacteria/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , Parede Celular/química , DNA Bacteriano/genética , Ácidos Graxos/química , Peptidoglicano/química , Fosfolipídeos/química , RNA Ribossômico 16S/genética , República da Coreia , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/química
9.
Int J Syst Evol Microbiol ; 70(5): 3295-3299, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32375943

RESUMO

A Gram-stain-positive, motile, rod-shaped and endospore-forming strain, SYSU K30002T, was isolated from a soil sample collected from a karst cave in Xingyi county, Guizhou province, south-west China. SYSU K30002T grew at 28-40 °C (optimum, 37 °C), at pH 5.0-8.0 (optimum, pH 7.0) and in the presence of 0-4 % (w/v) NaCl (optimum in the absence of NaCl). The cell-wall peptidoglycan type was A4α (Lys-Asp). The cell-wall sugars of SYSU K30002T were ribose, galactose and mannose, and MK-7 was the menaquinone. The major fatty acids were iso-C15 : 0, C16 : 1 ω7c alcohol and iso-C16 : 0. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and two unidentified phospholipids. The G+C content of the genomic DNA was 36.1 mol%. The average nucleotide identity values between SYSU K30002T and its closest relatives were below the cut-off level (95-96 %) for species delineation. Based on phenotypic, chemotaxonomic and genome comparisons, strain SYSU K30002T represents a novel species of the genus Lysinibacillus, for which the name Lysinibacillusantri sp. nov. is proposed. The type strain is SYSU K30002T (=KCTC 33955T=CGMCC 1.13504T).


Assuntos
Bacillaceae/classificação , Cavernas/microbiologia , Filogenia , Microbiologia do Solo , Bacillaceae/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , Parede Celular/química , China , DNA Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Peptidoglicano/química , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/química
10.
Int J Syst Evol Microbiol ; 70(5): 3406-3412, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32375947

RESUMO

A Gram-stain-positive, strictly aerobic and rod-shaped bacterium, designated as 3 H-10T, was isolated from a yellow water sample collected from the manufacturing process of strong flavor Chinese baijiu in Yibin region of Sichuan province (PR China). Oval endospores were formed at the subtermini of cells with swollen sporangia. The isolate was able to grow at temperatures of 20-45 °C (optimum growth at 37 °C), at pH 6.0-10.0 (optimum growth at pH 8.0) and in the presence of 0-2 % (w/v) NaCl (optimum growth with 0 % NaCl). Ribose was the major cell-wall sugar, and meso-diaminopimelic acid (meso-DAP) was the diagnostic amino acid. The main polar lipids of 3 H-10T included diphosphatidylglycerol (DPG), phosphatidylglycerol (PG) and phosphatidylethanolamine (PE). MK-7 was predominant menaquinone and iso-C15 : 0 (60.7 %) was the major fatty acid. Comparisons of 16S rRNA gene sequence indicated that 3 H-10T was most closely related to Bacillus mesophilus SA4T (96.30 %), Bacillus ginsengihumi Gsoil 114T (96.27 %) and Bacillus shackletonii LMG 18435T (96.27 %). The average nucleotide identity (ANI) values between strain 3 H-10T and the three type strains mentioned above were 69.56, 70.19 and 70.67 %, respectively. The genomic DNA G+C content was 35.4 mol%. On the basis of its phenotypic, chemotaxonomic and phylogenetic properties, strain 3 H-10T represents a novel species of the genus Bacillus, for which the name Bacillus aquiflavi sp. nov. is proposed. The type strain is Bacillus aquiflavi 3 H-10T (=CICC 24755T=JCM 33703T).


Assuntos
Bebidas Alcoólicas/microbiologia , Bacillus/classificação , Filogenia , Bacillus/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , Parede Celular/química , China , DNA Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Peptidoglicano/química , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Água
12.
Int J Food Microbiol ; 322: 108576, 2020 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-32240921

RESUMO

Aflatoxin contamination in food and feed products has been brought into sharp focus over the last few decades in the world. However, there is no effective strategy for solving the problem thus far. Therefore, basic research on the aflatoxin-producer Aspergillus flavus is an urgent need. The vital role of mitogen-activated protein kinases (MAPKs) in signal transduction has been documented in various pathogenic fungi, but their functions in A. flavus have rarely been investigated. Herein, we characterized the detailed function of one of these MAPKs, AflSlt2. Targeted deletion of AflSlt2 gene indicates that this kinase is required for vegetative growth, conidia generation, and sclerotium formation. The analysis of AflSlt2 deletion mutant revealed hypersensitivity to cell wall-damaging chemicals and resistance against hydrogen peroxide. Interestingly, the ability of the ΔAflSlt2 mutant to generate aflatoxins in medium was significantly increased compared to wild type. However, a pathogenicity assay indicated that the ΔAflSlt2 mutant was deficient in peanut infection. Site-directed mutation study uncovered that the function of AflSlt2 was dependent on the phosphorylated residues (Thr-186 and Tyr-188) within the activation loop and the phosphotransfer residue (Lys-52) within the subdomain II. Interestingly, an autophosphorylation mutant of AflSlt2 (AflSlt2R66S) displayed wild type-like phenotypes. Bringing these observations together, we propose that Slt2-MAPK pathway is involved in development, stress response, aflatoxin biosynthesis, and pathogenicity in A. flavus. This study may be useful to unveil the regulation mechanism of aflatoxin biosynthesis and provide strategy to control A. flavus contamination.


Assuntos
Aflatoxinas/biossíntese , Arachis/microbiologia , Aspergillus flavus/metabolismo , Proteínas Fúngicas/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Aspergillus flavus/crescimento & desenvolvimento , Aspergillus flavus/patogenicidade , Parede Celular/metabolismo , Proteínas Fúngicas/genética , Proteínas Quinases Ativadas por Mitógeno/genética , Mutação , Transdução de Sinais , Estresse Fisiológico
13.
Ecotoxicol Environ Saf ; 197: 110621, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32304924

RESUMO

Antimony (Sb) excess accumulation in edible parts of crops causes potential risks to human health. However, knowledge about the mechanisms of its accumulation within vegetable plants is still not well known. Here, we investigated the physiological processes of Sb involved in symplastic and apoplastic absorption, compartmentation by roots, and translocation in xylem in Brassica parachinensis L. exposed to antimonate (SbV) and antimonite (SbIII) forms. The results showed that plants treated with SbIII emerged to be more toxic than SbV as proved by the lower biomass and the higher concentrations of malonaldehyde (MDA) and hydrogen peroxide (H2O2) in plant tissues, especially at high dosages. The Sb concentration showed more in shoots but less in roots treated with SbV than with SbIII. The total Sb accumulation was higher under the SbV treatment than the SbIII treatment, mainly due to the higher accumulation in shoots. Additionally, the Sb concentration in symplastic flow of roots was higher exposed to SbV than SbIII, while no differences were found for the Sb concentration in apoplastic flow between them. Moreover, the Sb concentration in cell walls of roots was higher exposed to SbIII than SbV, especially at high levels. Furthermore, the Sb concentration in xylem was higher exposed to SbV than SbIII, and a greatly positive correlation was observed between the Sb concentrations in xylem and shoots. Overall, these findings revealed that vegetable plants accumulated more SbV than SbIII in edible parts mainly due to xylem translocation rather than root absorption.


Assuntos
Antimônio/farmacocinética , Brassica/metabolismo , Absorção Fisiológica , Antimônio/toxicidade , Transporte Biológico , Brassica/efeitos dos fármacos , Parede Celular/metabolismo , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Raízes de Plantas/metabolismo , Xilema/metabolismo
14.
Int J Food Microbiol ; 323: 108592, 2020 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-32315871

RESUMO

Microbial surface contamination of equipment or of food contact material is a recurring problem in the food industry. Spore-forming bacteria are far more resistant to a wide variety of treatments than their vegetative forms. Understanding the mechanisms underlying decontamination processes is needed to improve surface decontamination strategies against endospores potentially at the source of foodborne diseases or food-spoilage. Pulsed light (PL) with xenon lamps delivers high-energy short-time pulses of light with wavelengths in the range 200 nm-1100 nm and a high UV-C fraction. Bacillus subtilis spores were exposed to either PL or to continuous UV-C. Gel electrophoresis and western blotting revealed elimination of various proteins of the spore coat, an essential outer structure that protects spores from a wide variety of environmental conditions and inactivation treatments. Proteomic analysis confirmed the elimination of some spore coat proteins after PL treatment. Transmission electron microscopy of PL treated spores revealed a gap between the lamellar inner spore coat and the outer spore coat. Overall, spores of mutant strains with defects in genes coding for spore coat proteins were more sensitive to PL than to continuous UV-C. This study demonstrates that radiations delivered by PL contribute to specific damage to the spore coat, and overall to spore inactivation.


Assuntos
Bacillus subtilis/metabolismo , Bacillus subtilis/efeitos da radiação , Proteínas do Capsídeo/metabolismo , Proteínas do Capsídeo/efeitos da radiação , Descontaminação/métodos , Luz , Bacillus subtilis/genética , Parede Celular/metabolismo , Parede Celular/efeitos da radiação , Descontaminação/normas , Proteômica , Esporos Bacterianos/fisiologia , Esporos Bacterianos/efeitos da radiação
15.
Int J Syst Evol Microbiol ; 70(5): 3069-3075, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32223833

RESUMO

A novel marine actinomycete, designated strain KJ-029T, was isolated from a marine sediment sample (water depth of 226 m) in Kagoshima, Japan. 16S rRNA gene sequence analysis revealed that the new isolate was most closely related to Micromonospora craniellae LHW 63014T (99.3 % similarity). Phylogenetic analyses of the genus Micromonospora based on 16S rRNA gene sequences showed that strain KJ-029T was clustered with Micromonospora craniellae LHW 63014T and Micromonospora endophytica 202201T. However, digital DNA-DNA hybridization analyses presented low levels of relatedness in the range of 24.8-32.9 % between strain KJ-029T and the above closely related strains. The novel strain contained meso-diaminopimelic acid and 3-OH-diaminopimelic acid, d-glutamic acid, glycine and d-alanine in the cell-wall peptidoglycan. The acyl type of the peptidoglycan was glycolyl and mycolic acids were absent. The major menaquinone was MK-9(H4). The whole-cell sugars consisted of glucose, mannose, xylose and ribose. Phosphatidylethanolamine was detected as the major phospholipid and corresponded to phospholipid type II. The predominant cellular fatty acid was iso-C16 : 0. The DNA G+C content of the genomic DNA was 71.5 mol%. Based on the present polyphasic study, strain KJ-029T represents a novel species of the genus Micromonospora, for which the name Micromonospora pelagivivens sp. nov. is proposed. The type strain is KJ-029T (=NBRC 113519T=TBRC 9233T).


Assuntos
Sedimentos Geológicos/microbiologia , Micromonospora/classificação , Filogenia , Técnicas de Tipagem Bacteriana , Composição de Bases , Parede Celular/química , DNA Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Graxos/química , Japão , Micromonospora/isolamento & purificação , Hibridização de Ácido Nucleico , Peptidoglicano/química , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Água do Mar/microbiologia , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados
16.
Int J Syst Evol Microbiol ; 70(5): 3027-3036, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32223834

RESUMO

A pink-coloured bacterium (strain KR32T) was isolated from cheese and assigned to the 'Arthrobacter agilis group'. Members of the 'pink Arthrobacter agilis group' form a stable clade (100 % bootstrap value) and contain the species Arthrobacter agilis, Arthrobacter ruber and Arthrobacter echini, which share ≥99.0 % 16S rRNA gene sequence similarity. Isolate KR32T showed highest 16S rRNA gene sequence similarity (99.9 %) to A. agilis DSM 20550T. Additional multilocus sequence comparison confirmed the assignment of strain KR32T to the clade 'pink A. agilis group'. Average nucleotide identity and digital DNA-DNA hybridization values between isolate KR32T and A. agilis DSM 20550T were 82.85 and 26.30 %, respectively. The G+C content of the genomic DNA of isolate KR32T was 69.14 mol%. Chemotaxonomic analysis determined anteiso-C15 : 0 as the predominant fatty acid and MK-9(H2) as the predominant menaquinone. Polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and monoacyldimannosyl-monoacylglycerol. The peptidoglycan type of the isolate was A3α. The carotenoid bacterioruberin was detected as the major pigment. At 10 °C, strain KR32T grew with increased concentrations of bacterioruberin and production of unsaturated fatty acids. Strain KR32T was a Gram-stain-positive, catalase-positive, oxidase-positive and coccus-shaped bacterium with optimal growth at 27-30 °C and pH 8. The results of phylogenetic and phenotypic analyses enabled the differentiation of the isolate from other closely related species of the 'pink A. agilis group'. Therefore, strain KR32T represents a novel species for which the name Arthrobacter bussei sp. nov. is proposed. The type strain is KR32T (=DSM 109896T=LMG 31480T=NCCB 100733T).


Assuntos
Arthrobacter/classificação , Queijo/microbiologia , Microbiologia de Alimentos , Filogenia , Animais , Arthrobacter/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , Bovinos , Parede Celular/química , DNA Bacteriano/genética , Ácidos Graxos/química , Feminino , Alemanha , Glicolipídeos/química , Leite , Hibridização de Ácido Nucleico , Peptidoglicano/química , Fosfolipídeos/química , Pigmentação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/química
17.
Food Chem ; 321: 126707, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32244134

RESUMO

Mealiness is one of the most important textural failure of apple fruit and four patterns of mealiness involving five apple cultivars were identified as the rapid, moderate, slow and none, requiring 3, 7, 14, 49 days at 25 °C, respectively. In comparison with the non-mealy 'Fuji' apple, parenchyma cells of mealy apples became detached and remained intact. Highly methyl-esterified homogalacturonan was strongly immunolabeled in the cell wall of slow and non-mealy apples. The mobility of water was enhanced in the cell wall during mealiness. Principal components analysis of FTIR spectra discriminated the cell wall materials (CWM) based on the mealiness progress. Heavy loss of CWM and its water-insoluble fractions but limited increase of water-soluble fractions, and the increase of crystalline micelles of CWM were closely associated with the mealiness progress. Overall, the occurrence of mealiness might attribute to structural, physical and biochemical modifications of CWM during tissue senescence.


Assuntos
Parede Celular/química , Malus/química , Pectinas/química , Frutas/química , Refeições
18.
Environ Pollut ; 263(Pt B): 114546, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32311624

RESUMO

In southern China, Brassica napus (rapeseed) is a widely planted oilseed crop in rice-rapeseed rotation systems with characteristically high levels of cadmium (Cd) and low levels of available boron (B). Current knowledge of the ameliorative effects of B on Cd toxicity in plants mainly concerns plant growth, Cd uptake, and Cd translocation, while little attention has been paid to the role of B on plant antioxidant enzyme systems and cell wall chelation of Cd. We explored the mechanisms whereby B improves rapeseed Cd resistance. Application of B alleviated Cd-induced oxidative stress caused by reactive oxygen species (ROS) in the shoots of Cd-treated plants, by increasing the activity of the major antioxidant enzymes, superoxide dismutase, peroxidase, and catalase. Moreover, the shoots of rapeseed plants supplied with B under Cd toxicity had higher ionic soluble pectin (ISP) content, thereby providing more Cd-binding sites in pectin, as well as higher methylesterase activity. However, no changes in covalent soluble pectin were observed. In addition, B also induced higher cellulose in Cd-toxic shoots, thus promoting Cd chelation onto cell walls. Fourier infrared spectrum analysis confirmed that the addition of B increased protein, pectin, cellulose, and carbohydrate content in the cell walls of Cd-toxic leaves. In conclusion, B can mitigate Cd phytotoxicity by alleviating oxidative stress and immobilizing Cd on the ISP and cellulose of shoot cell walls, thereby playing a potential role in improving the growth potential of crops and Cd phytoremediation. The results also provide a theoretical basis for alleviating Cd toxicity in crops and development of Cd-tolerant varieties.


Assuntos
Brassica napus , Poluentes do Solo , Boro , Cádmio/análise , Parede Celular , China , Estresse Oxidativo , Raízes de Plantas/química
19.
Sci Total Environ ; 728: 138833, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32339843

RESUMO

In Southern China, rice-oil rotations occur on soils with high levels of cadmium (Cd) and low levels of available boron (B). Boron can alleviate Cd toxicity, as it affects the plant cell wall structures and the components that block the entry of Cd into the cytoplasm; however, these mechanisms are not well understood. Fourier transform infrared spectroscopy (FTIR), fluorescent probe dye, electron microscope, ion abundance (inductively coupled plasma mass spectrometry), metabonomics and transcriptomics were used in the study, and we found that under Cd stress, B increased root pectin content by affecting the biosynthesis pathways and decreasing the activity of pectinase and the expression levels of related genes. The increased pectin content and pectin demethylation increased the chelation of Cd onto the cell walls and reduced the levels of Cd entering the organelles. Application of B to the roots decreased the amounts of cellulose and hemicellulose in the cell walls to normal levels and promoted the expression of genes from the expansin, xyloglucan endotransglucosylase, and α-xylosidase families. This contributed to cell wall integrity and root flexibility. Consequently, the accumulation of reactive oxygen species was inhibited and cell viability in the roots was increased, which reduced the destruction of root surface structures. These results have improved our understanding of how B participates in chelation of Cd onto cell walls and in maintaining cell wall integrity, thereby improving Cd toxicity resistance in rapeseed roots.


Assuntos
Brassica napus , Cádmio , Boro , Parede Celular , China , Raízes de Plantas
20.
Phytochemistry ; 175: 112370, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32289597

RESUMO

Peptidoglycan has been retained in chloroplasts that have evolved from cyanobacteria along some evolutionary tracks, but has seemingly been quickly eliminated during evolution of others. It has been eliminated in Rhodophyta, Chlorophyta, Pteridophyta and Spermatophyta, but has been retained in streptophyte algae, Glaukophyta, and Lycophyta. In this article questions emerging from this are raised, and for some of them answers are suggested.


Assuntos
Clorófitas , Eucariotos , Parede Celular , Cloroplastos , Peptidoglicano , Filogenia
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