RESUMO
To find effective silver nanoparticles (AgNPs) for control of phytopathogens, in this study, two strains of actinomycetes isolated from the soil of the Brazilian biome Caatinga (Caat5-35) and from mangrove sediment (Canv1-58) were utilized. The strains were identified by using the 16S rRNA gene sequencing as Streptomyces sp., related to Streptomyces mimosus species. The obtained AgNPs were coded as AgNPs 35 and AgNPs58 and characterized by size and morphology using dynamic light scattering, zeta potential, transmission electron microscopy, and Fourier transformed infrared (FTIR). The antifungal activity of the AgNPs35 and AgNPs58 was evaluated in vitro by the minimal inhibitory concentration (MIC) assay on the phytopathogens, Alternaria solani, Alternaria alternata, and Colletotrichum gloeosporioides. The phytotoxic effect was evaluated by the germination rate and seedling growth of rice (Oryza sativa). AgNPs35 and AgNPs58 showed surface plasmon resonance and average sizes of 30 and 60 nm, respectively. Both AgNPs presented spherical shape and the FTIR analysis confirmed the presence of functional groups such as free amines and hydroxyls of biomolecules bounded to the external layer of the nanoparticles. Both AgNPs inhibited the growth of the three phytopathogens tested, and A. alternate was the most sensible (MIC ≤ 4 µM). Moreover, the AgNPs35 and AgNPs58 did not induce phytotoxic effects on the germination and development of rice seedlings. In conclusion, these AgNPs are promising candidates to biocontrol of these phytopathogens without endangering rice plants.
Assuntos
Actinobacteria , Nanopartículas Metálicas , Oryza , Nanopartículas Metálicas/toxicidade , Prata/toxicidade , Actinomyces , RNA Ribossômico 16S/genética , Sementes , Plântula , Antibacterianos/farmacologiaRESUMO
We have established how natural compounds from green propolis collected by the species Apis mellifera act against the growth of Pythium aphanidermatum. On the basis of mass spectrometry (Q-ToF MS), we determined that Artepillin C, the major constituent of green propolis, underlies the effect and displays activity against P. aphanidermatum at a minimal inhibitory concentration of 750 µg.mL-1. Biophysical studies based on model membranes showed that this inhibitory effect may be linked with a membrane-related phenomenon: Artepillin C increases the permeability of membranes with relatively high fluidity in their lateral structure, a feature that is in line with the lipid composition reported for the cytoplasmic membrane of P. aphanidermatum. Therefore, the present study supports the use of the effective and inexpensive green propolis to control the impact of the dangerous phytopathogen P. aphanidermatum on agriculture.
Assuntos
Antifúngicos/farmacologia , Fenilpropionatos/farmacologia , Própole/química , Pythium/efeitos dos fármacos , Animais , Antifúngicos/isolamento & purificação , Abelhas , Espectrometria de Massas , Testes de Sensibilidade Microbiana , Fenilpropionatos/isolamento & purificaçãoRESUMO
In this study, 16S rRNA gene amplicon sequencing was used to assess bacterial diversity and dynamics throughout different stages of leaves decomposition of three plant species (Rhizophora mangle, Laguncularia racemosa, and Avicennia schaueriana) in three distinct mangroves of São Paulo state, Brazil. The experiments were conducted in microcosms. Phylogenetic diversity (Faiths' PD) index showed differences between samples and suggested that some treatments like R. mangle increased their bacterial diversity through time. Principal coordinate analysis revealed that community's profile varied based on mangroves, followed by plant species and time. A clear succession patterns was observed in this study, i.e., some microorganisms with low abundance in the initial phases gradually became dominant (e.g., Alphaproteobacteria), whereas microbes that were initially predominant became low (e.g., Gammaproteobacteria). Co-occurrence analyses were performed for all times of plant degradation aiming to better understand the relationships between bacterial populations. The c-score index was done to test the randomness of the community assemblage during the stages of decomposition. For all degradation time points, the values of the observed c-score were higher than the values of the simulated c-score. This result indicated that during plant decomposition, the bacterial communities presented less co-occurrence than expected by chance and that these communities were not randomly assembled but instead they are driven by species interactions. Network analyses results showed that in the conditions presented in this experiment, the initial stages of leaf decomposition formed more connected and complex networks than the later stages. These results suggest that resource competition was a determinant in these specific mangroves during plant degradation, mainly in the initial periods.
Assuntos
Avicennia/microbiologia , Bactérias/crescimento & desenvolvimento , Combretaceae/microbiologia , Microbiota , Folhas de Planta/microbiologia , Rhizophoraceae/microbiologia , Bactérias/classificação , Brasil , RNA Bacteriano/análise , RNA Ribossômico 16S/análise , Análise de Sequência de RNARESUMO
Thirteen Gram-negative, aerobic, motile with polar flagella, rod-shaped bacteria were isolated from root nodules of Centrolobium paraense Tul. grown in soils from the Amazon region of Brazil. Growth of strains was observed at temperature range 20-36 °C (optimal 28 °C), pH ranges 5-11 (optimal 6.0-7.0), and 0.1-0.5%NaCl (optimal 0.1-0.3%). Analysis of 16S rRNA gene placed the strains into two groups within Bradyrhizobium. Closest neighbouring species (98.8%) for group I was B. neotropicale while for group II were 12 species with more than 99% of similarity. Multi-locus sequence analysis (MLSA) with dnaK, glnII, recA, and rpoB confirmed B. neotropicale BR 10247T as the closest type strain for the group I and B. elkanii USDA 76T and B. pachyrhizi PAC 48T for group II. Average Nucleotide Identity (ANI) differentiated group I from the B. neotropicale BR 10247T (79.6%) and group II from B. elkanii USDA 76T and B. pachyrhizi PAC 48T (88.1% and 87.9%, respectively). Fatty acid profiles [majority C16:0 and Summed feature 8 (18:1ω6c/18:1ω7c) for both groups], DNA G + C content, and carbon compound utilization supported the placement of the novel strains in the genus Bradyrhizobium. Gene nodC and nifH of the new strains have in general low similarity with other Bradyrhizobium species. Both groups nodulated plants from the tribes Crotalarieae, Dalbergiae, Genisteae, and Phaseoleae. Based on the presented data, two novel species which the names Bradyrhizobium centrolobii and Bradyrhizobium macuxiense are proposed, with BR 10245T (=HAMBI 3597T) and BR 10303T (=HAMBI 3602T) as the respective-type strains.
Assuntos
Bradyrhizobium , Fabaceae/microbiologia , Nódulos Radiculares de Plantas/microbiologia , Proteínas de Bactérias/genética , Composição de Bases/genética , Bradyrhizobium/classificação , Bradyrhizobium/genética , Bradyrhizobium/isolamento & purificação , Brasil , DNA Bacteriano/genética , Ácidos Graxos/química , Tipagem de Sequências Multilocus , N-Acetilglucosaminiltransferases/genética , Fixação de Nitrogênio/genética , Fixação de Nitrogênio/fisiologia , Hibridização de Ácido Nucleico , Oxirredutases/genética , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Solo , Microbiologia do SoloRESUMO
This review summarizes the reports on antibacterial compounds that have been obtained from marine-derived bacteria during the period 2010-2015. Over 50 active compounds were isolated during this period, most of which (69%) were obtained from Actinobacteria. Several compounds were already known, such as etamycin A (11) and nosiheptide (65), and new experiments with them showed some previously undetected antibacterial activities, highlighting the fact that known natural products may be an important source of new antibacterial leads. New broad-spectrum antibacterial compounds were reported with activity against antibiotic resistant Gram-positive and Gram-negative bacteria. Anthracimycin (33), kocurin (66), gageotetrins A-C (72-74), and gageomacrolactins 1-3 (86-88) are examples of compounds that display promising properties and could be leads to new antibiotics. A number of microbes produced mixtures of metabolites sharing similar chemical scaffolds, and structure-activity relationships are discussed.
Assuntos
Actinobacteria/química , Antibacterianos/química , Bactérias/efeitos dos fármacos , Macrolídeos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
The Antarctic endophytic fungus (strain ITA1-CCMA 952) was isolated from the moss Schistidium antarctici found in Admiralty Bay, King George Island, Antarctica. Strain ITA1-CCMA 952 was assigned to the specie Mortierella alpina by phylogenetic analysis based on 18S rRNA gene sequences. This strain produces high levels of polyunsaturated fatty acids (PUFAs), including y-(gamma) linolenic acid and arachidonic acid, which when combined represents 48.3% of the total fatty acid content. Fungal extracts demonstrated strong antioxidant activity with the EC50 value of 48.7 µg mL(-1) and also a strong antibacterial activity, mainly against the following bacteria: Escherichia coli, with a MIC of 26.9 µg mL(-1) and Pseudomonas aeruginosa and Enterococcus faecalis, both with a MIC of 107 µg mL(-1). A GC-MS analysis of the chloroform fraction obtained from the crude extract revealed the presence of potential antimicrobials (Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) and Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(phenylmethyl)) as the major compounds. Therefore, the M. alpina strain ITA1-CCMA 952 is a promising fungus for the biotechnological production of antibiotics, antioxidant substances and PUFAs. This study highlights the need for more research in extreme environments, such as Antarctica.
Assuntos
Bryopsida/microbiologia , Mortierella/isolamento & purificação , Antibacterianos/análise , Ácidos Graxos/análise , Mortierella/química , Mortierella/genética , RNA Fúngico/genética , RNA Ribossômico 18S/genéticaRESUMO
Mangroves are coastal environments that provide resources for adjacent ecosystems due to their high productivity, organic matter decomposition, and carbon cycling by microbial communities in sediments. Since the industrial revolution, the increase of Greenhouse Gases (GHG) released due to fossil fuel burning led to many environmental abnormalities such as an increase in average temperature and ocean acidification. Based on the hypothesis that climate change modifies the microbial diversity associated with decaying organic matter in mangrove sediments, this study aimed to evaluate the microbial diversity under simulated climate change conditions during the litter decomposition process and the emission of GHG. Thus, microcosms containing organic matter from the three main plant species found in mangroves throughout the State of São Paulo, Brazil (Rhizophora mangle, Laguncularia racemosa, and Avicennia schaueriana) were incubated simulating climate changes (increase in temperature and pH). The decay rate was higher in the first seven days of incubation, but the differences between the simulated treatments were minor. GHG fluxes were higher in the first ten days and higher in samples under increased temperature. The variation in time resulted in substantial impacts on α-diversity and community composition, initially with a greater abundance of Gammaproteobacteria for all plant species despite the climate conditions variations. The PCoA analysis reveals the chronological sequence in ß-diversity, indicating the increase of Deltaproteobacteria at the end of the process. The GHG emission varied in function of the organic matter source with an increase due to the elevated temperature, concurrent with the rise in the Deltaproteobacteria population. Thus, these results indicate that under the expected climate change scenario for the end of the century, the decomposition rate and GHG emissions will be potentially higher, leading to a harmful feedback loop of GHG production. This process can happen independently of an impact on the bacterial community structure due to these changes.
RESUMO
Aspergillus tubingensis and Bionectria ochroleuca showed excellent extracellular ability to synthesize silver nanoparticles (Ag NP), spherical in shape and 35 ± 10 nm in size. Ag NP were characterized by transmission electron microscopy, X-ray diffraction analysis, and photon correlation spectroscopy for particle size and zeta potential. Proteins present in the fungal filtrate and in Ag NP dispersion were analyzed by electrophoresis (sodium dodecyl sulfate polyacrylamide gel electrophoresis). Ag NP showed pronounced antifungal activity against Candida sp, frequently occurring in hospital infections, with minimal inhibitory concentration in the range of 0.11-1.75 µg/mL. Regarding antibacterial activity, nanoparticles produced by A. tubingensis were more effective compared to the other fungus, inhibiting 98.0 % of Pseudomonas. aeruginosa growth at 0.28 µg/mL. A. tubingensis synthesized Ag NP with surprisingly high and positive surface potential, differing greatly from all known fungi. These data open the possibility of obtaining biogenic Ag NP with positive surface potential and new applications.
Assuntos
Antibacterianos/metabolismo , Antibacterianos/farmacologia , Aspergillus/metabolismo , Hypocreales/metabolismo , Nanopartículas Metálicas/química , Prata/metabolismo , Antibacterianos/química , Pseudomonas aeruginosa/efeitos dos fármacosRESUMO
The chemical reactions carried out by microorganisms have been used as a tool in modern chemistry. This paper reports the production of mycophenolic acid and a new phthalide by the endophytic fungus Penicillium crustosum obtained from coffee seeds. The fungus was cultivated in a liquid medium for a period of seven days and after that the culture medium was divided into four treatments: A, B, C and D, to which different organic substances were added. Treatment A was maintained as the control to evaluate the occurrence of biotransformation. Organic acids were added to the culture media of treatments B (ferulic and quinic acids) and C [cinnamic and 3,4-(methylenedioxy) cinnamic acids], and caffeine was added in the treatment D. All these organic compounds were dissolved in DMSO, and the fermentation was maintained for more 13 days, totalizing 20 days. Mycophenolic acid was isolated from the culture with no added acids (treatment A). Mycophenolic acid and a new phthalide, 5-hydroxy-7-methoxy-4-methylphthalide were isolated from treatments B and C, and mycophenolic acid and caffeine (added to the culture medium) were isolated from treatment D. The structures were determined by NMR techniques and confirmed by MS and MS/MS techniques.
Assuntos
Benzofuranos/metabolismo , Ácido Micofenólico/biossíntese , Penicillium/metabolismo , Benzofuranos/química , Biotransformação , Café/microbiologia , Meios de Cultura , Espectroscopia de Ressonância Magnética , Ácido Micofenólico/química , Espectrometria de Massas em Tandem , Fatores de TempoRESUMO
Paper spray mass spectrometry (PS-MS) is an ambient ionization technique that allows for rapid and direct mass spectrometry analysis for a wide range of chemical compounds due to its portability, little to no sample preparation, and cost-effective materials. As applications with this technique continue to expand, the identification and discrimination of bacteria at the strain level remain a promising avenue for researchers. Although studies in the past demonstrated the applicability of PS-MS to discriminate bacteria at the strain level, no one has reported the strain-level differentiation of actinobacteria without using solvent for PS-MS. Hence, this study demonstrates that optimization of PS-MS permits the investigation and differentiation of the metabolic profiles of actinobacteria without the need for solvents, diminishing the potential for sample contamination and consequently increasing the versatility of this technique. In doing so, strains of actinobacteria (CAAT P5-21, CAAT P5-16, CAAT 8-25, CAAT P8-92, and CAAT P11-13) were grown and transferred to produce a crude growth medium. The supernatant was used for the PS-MS analyses using a Thermo Scientific LTQ mass spectrometer. Multivariate statistical analysis, including principal component analysis (PCA) and hierarchal cluster analysis (HCA), was employed to chemically distinguish the strains of bacteria. As a result, each strain of actinobacteria could be visually differentiated based on their metabolic profile. These findings demonstrate the practicability of using a liquid medium as an alternative to many other organic solvents when analyzing bacteria, making PS-MS a crucial addition to a microbiologist's research toolkit.
Assuntos
Actinobacteria , Actinobacteria/metabolismo , Solo , Espectrometria de Massas/métodos , Bactérias , Solventes/química , Metaboloma , PapelRESUMO
The genus Leuconostoc belongs to a group of lactic acid bacteria usually isolated from fermented vegetables, which includes species involved in the production of exopolysaccharides (EPS). These biopolymers possess considerable commercial potential. Because of the wide variety of industrial applications of EPS, this study aimed to produce and characterize the native exopolysaccharide strain Leuconostoc pseudomesenteroides R2, which was isolated from cabbage collected in a semi-arid region of Bahia. We employed the following conditions for the production of EPS: 10.7% sucrose, pH 8.2, without agitation and incubation at 28ºC for 30 hours. The fermentation broth was treated with ethanol and generated two types of polysaccharide substances (EPS I and EPS II). The identification of EPS I and EPS II was conducted using FT-IR, (1)H, (13)C and DEPT-135 NMR spectra. The two substances were identified as linear dextran α polysaccharides (1 â 6) which indicated different characteristics with respect to thermal analysis and density of free packaging, viscosity and time of solubilization. Both dextrans are of low density, possess high thermal stability and exhibited the behavior characteristic of pseudoplastic polymers.
Assuntos
Brassica/microbiologia , Leuconostoc/metabolismo , Polissacarídeos Bacterianos/biossíntese , Fermentação , Espectroscopia de Ressonância Magnética , Polissacarídeos Bacterianos/isolamento & purificação , ViscosidadeRESUMO
Leaf decomposition is the primary process in release of nutrients in the dynamic mangrove habitat, supporting the ecosystem food webs. On most environments, fungi are an essential part of this process. However, due to the peculiarities of mangrove forests, this group is currently neglected. Thus, this study tests the hypothesis that fungal communities display a specific succession pattern in different mangrove species and this due to differences in their ecological role. A molecular approach was employed to investigate the dynamics of the fungal community during the decomposition of three common plant species (Rhizophora mangle, Laguncularia racemosa, and Avicennia schaueriana) from a mangrove habitat located at the southeast of Brazil. Plant material was the primary driver of fungi communities, but time also was marginally significant for the process, and evident changes in the fungal community during the decomposition process were observed. The five most abundant classes common to all the three plant species were Saccharomycetes, Sordariomycetes, Tremellomycetes, Eurotiomycetes, and Dothideomycetes, all belonging to the Phylum Ascomycota. Microbotryomycetes class were shared only by A. schaueriana and L. racemosa, while Agaricomycetes class were shared by L. racemosa and R. mangle. The class Glomeromycetes were shared by A. schaueriana and R. mangle. The analysis of the core microbiome showed that Saccharomycetes was the most abundant class. In the variable community, Sordariomycetes was the most abundant one, mainly in the Laguncularia racemosa plant. The results presented in this work shows a specialization of the fungal community regarding plant material during litter decomposition which might be related to the different chemical composition and rate of degradation.
Assuntos
Avicennia , Combretaceae , Microbiota , Rhizophoraceae , Avicennia/metabolismo , Brasil , Folhas de Planta/metabolismo , Plantas , Rhizophoraceae/microbiologiaRESUMO
Acremonium camptosporum, a fungus associated with the marine sponge Aplysina fulva, was collected from the isolated mid-Atlantic Saint Peter and Saint Paul Archipelago, Brazil, and was found to produce secondary metabolites that displayed antibacterial activities. Mass spectra data obtained by UPLC-ESI-MS/MS analyses of these extracts were compared to several databases and revealed the presence of several different cytotoxic acremonidins and acremoxanthones. The close association between the sponge and the fungi with its compounds could be of strategic importance in defending both from the high predation pressure and spatial competition in the warm-water scarps of the islands.
Assuntos
Acremonium , Poríferos , Animais , Brasil , Ilhas , Espectrometria de Massas em TandemRESUMO
The bacterial diversity present in sediments of a well-preserved mangrove in Ilha do Cardoso, located in the extreme south of São Paulo State coastline, Brazil, was assessed using culture-independent molecular approaches (denaturing gradient gel electrophoresis (DGGE) and analysis of 166 sequences from a clone library). The data revealed a bacterial community dominated by Alphaproteobacteria (40.36% of clones), Gammaproteobacteria (19.28% of clones) and Acidobacteria (27.71% of clones), while minor components of the assemblage were affiliated to Betaproteobacteria, Deltaproteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. The clustering and redundancy analysis (RDA) based on DGGE were used to determine factors that modulate the diversity of bacterial communities in mangroves, such as depth, seasonal fluctuations, and locations over a transect area from the sea to the land. Profiles of specific DGGE gels showed that both dominant ('universal' Bacteria and Alphaproteobacteria) and low-density bacterial communities (Betaproteobacteria and Actinobacteria) are responsive to shifts in environmental factors. The location within the mangrove was determinant for all fractions of the community studied, whereas season was significant for Bacteria, Alphaproteobacteria, and Betaproteobacteria and sample depth determined the diversity of Alphaproteobacteria and Actinobacteria.
Assuntos
Bactérias/classificação , Bactérias/crescimento & desenvolvimento , Biodiversidade , Sedimentos Geológicos/microbiologia , Rhizophoraceae/microbiologia , Microbiologia do Solo , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/crescimento & desenvolvimento , Alphaproteobacteria/classificação , Alphaproteobacteria/genética , Alphaproteobacteria/crescimento & desenvolvimento , Bactérias/genética , Bacteroidetes/classificação , Bacteroidetes/genética , Bacteroidetes/crescimento & desenvolvimento , Composição de Bases , Betaproteobacteria/classificação , Betaproteobacteria/genética , Betaproteobacteria/crescimento & desenvolvimento , Brasil , DNA Bacteriano/análise , DNA Bacteriano/genética , Deltaproteobacteria/classificação , Deltaproteobacteria/genética , Deltaproteobacteria/crescimento & desenvolvimento , Ecossistema , Gammaproteobacteria/classificação , Gammaproteobacteria/genética , Gammaproteobacteria/crescimento & desenvolvimento , Variação Genética , Sedimentos Geológicos/análise , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/análise , RNA Ribossômico 16S/genética , Água do Mar , Análise de Sequência de DNA , TemperaturaRESUMO
Social interactions impact microbial communities and these relationships are mediated by small molecules. The chemical ecology of bacteria on the phylloplane environment is still little explored. The harsh environmental conditions found on leaf surface require high metabolic performances of the bacteria in order to survive. That is interesting both for scientific fields of prospecting natural molecules and for the ecological studies. Important queries about the bacterial lifestyle on leaf surface remain not fully comprehended. Does the hostility of the environment increase the populations' cellular altruism by the production of molecules, which can benefit the whole community? Or does the reverse occur and the production of molecules related to competition between species is increased? Does the phylogenetic distance between the bacterial populations influence the chemical profile during social interactions? Do phylogenetically related bacteria tend to cooperate more than the distant ones? The phylloplane contains high levels of yet uncultivated microorganisms, and understanding the molecular basis of the social networks on this habitat is crucial to gain new insights on the ecology of the mysterious community members due to interspecies molecular dependence. Here, we review and discuss what is known about bacterial social interactions and their chemical lifestyle on leaf surface.
Assuntos
Bactérias/isolamento & purificação , Microbiota , Folhas de Planta/microbiologia , Bactérias/classificação , Bactérias/genética , Ecossistema , FilogeniaRESUMO
Mangroves are dynamic and unique ecosystems that provide important ecological services to coastal areas. The phylloplane is one of the greatest microbial habitats, and most of its microorganisms are uncultivated under common laboratory conditions. Bacterial community structure of Laguncularia racemosa phylloplane, a well-adapted mangrove species with salt exudation at foliar levels, was accessed through 16S rRNA amplicon sequencing. Sampling was performed in three different sites across a transect from upland to the seashore in a preserved mangrove forest located in the city of Cananéia, São Paulo State, Brazil. Higher bacterial diversity was observed in intermediary locations between the upland and the seashore, showing that significant intraspecific spatial variation in bacterial communities exists between a single host species with the selection of specific population between an environmental transect.
Assuntos
Bactérias/isolamento & purificação , Biodiversidade , Combretaceae/microbiologia , Bactérias/classificação , Bactérias/genética , Brasil , DNA Bacteriano/genética , Ecossistema , RNA Ribossômico 16S/genética , Áreas AlagadasRESUMO
Drylands occupy approximately 41% of the Earth's terrestrial surface. Climate change and land use practices are expected to affect biogeochemical cycling by the soil microbiome in these ecosystems. Understanding how soil microbial community might respond to these drivers is extremely important to mitigate the processes of land degradation and desertification. The Caatinga, an exclusively Brazilian biome composed of an extensive seasonal tropical dry forest, is exposed to variable spatiotemporal rainfall patterns as well as strong human-driven pressures. Herein, an integrated analysis of shotgun metagenomics approach coupled to meteorological data was employed to unravel the impact of seasonality and land use change on soil microbiome from preserved and agriculture-affected experimental fields in Caatinga drylands. Multivariate analysis suggested that microbial communities of preserved soils under seasonal changes were shaped primarily by water deficit, with a strong increase of Actinobacteria and Proteobacteria members in the dry and rainy seasons, respectively. In contrast, nutrient availability notably played a critical role in driving the microbial community in agriculture-affected soils. The strong enrichment of bacterial genera belonging to the poorly-known phylum Acidobacteria ('Candidatus Solibacter' and 'Candidatus Koribacter') in soils from dry season affected by ferti-irrigation practices presupposes a contrasting copiotrophic lifestyle and ecological role in mitigating the impact of chemical fertilization. Functional analyses identify overrepresented genes related to osmotic stress response (synthesis of osmoprotectant compounds, accumulation of potassium ions) and preferential carbon and nitrogen utilization when comparing the microbiome of preserved soils under seasonal changes, reflecting differences in the genetic potential for nutrient cycling and C acquisition in the environment. However, the prevalence of nitrosative stress and denitrification functions in irrigation/fertilization-affected soils of the dry season clearly suggest that nutrient input and disruption of natural water regime may impact biogeochemical cycles linked to the microbial processes, with potential impacts on the ecosystem functionality. These findings help to better understand how natural seasonality and agricultural management differentially affect soil microbial ecology from dry forests, providing support for the development of more sustainable land management in dryland ecosystems.
RESUMO
A new polycyclic antibiotic, pradimicin-IRD, was isolated from actinobacteria Amycolatopsis sp. IRD-009 recovered from soil of Brazilian rainforest undergoing restoration area. This molecule is the major compound produced in solid culture media. The new compound was detected by a focused method of precursor ion (high-performance liquid chromatography coupled to tandem mass spectrometer) developed previously to identify unusual aminoglycosyl sugar moieties. The compound was isolated and its structure was, therefore, elucidated by high-resolution mass spectrometry, and 1D and 2D nuclear magnetic resonance experiments. Pradimicin-IRD displayed potential antimicrobial activity against Streptococcus agalactiae (MIC 3.1 µg/mL), Pseudomonas aeruginosa (MIC 3.1 µg/mL) and Staphylococcus aureus (MIC 3.1 µg/mL), and also cytotoxicity against tumour and non-tumour cell lines with IC50 values ranging from 0.8 µM in HCT-116 colon carcinoma cells to 2.7 µM in MM 200 melanoma cells. Particularly, these biological properties are described for the first time for this chemical class.
Assuntos
Actinobacteria/química , Antraciclinas/isolamento & purificação , Antibacterianos/isolamento & purificação , Antraciclinas/química , Antibacterianos/química , Brasil , Linhagem Celular , Linhagem Celular Tumoral , Cromatografia Líquida de Alta Pressão , Humanos , Concentração Inibidora 50 , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/efeitos dos fármacos , Microbiologia do Solo , Staphylococcus aureus/efeitos dos fármacos , Espectrometria de Massas em TandemRESUMO
BACKGROUND: Mangroves are important coastal ecosystems known for high photosynthetic productivity and the ability to support marine food chains through supply of dissolved carbon or particular organic matter. Most of the carbon found in mangroves is produced by its vegetation and is decomposed in root associated sediment. This process involves a tight interaction between microbial populations, litter chemical composition, and environmental parameters. Here, we study the complex interactions found during litter decomposition in mangroves by applying network analysis to metagenomic data. METHODS: Leaves of three species of mangrove trees typically found in the southeast of Brazil (Rhizophora mangle, Laguncularia racemosa, and Avicennia schaueriana) were collected in separate litter bags and left on three different mangroves for 60 days. These leaves were subsequently used for metagenome sequencing using Ion Torrent technology. Sequences were annotated in MG-RAST and used for network construction using MENAp. RESULTS: The most common phyla were Proteobacteria (classes Gamma and Alphaproteobacteria) followed by Firmicutes (Clostridia and Bacilli). The most abundant protein clusters were associated with the metabolism of carbohydrates, amino acids, and proteins. Non-metric multidimensional scaling of the metagenomic data indicated that substrate (i.e., tree species) did not significantly select for a specific community. Both networks exhibited scale-free characteristics and small world structure due to the low mean shortest path length and high average clustering coefficient. These networks also had a low number of hub nodes most of which were module hubs. DISCUSSION: This study demonstrates that under different environmental pressures (i.e., plant species or mangrove location) the microbial community associated with the decaying material forms a robust and stable network.
RESUMO
The litterfall is the major organic material deposited in soil of Brazilian Caatinga biome, thus providing the ideal conditions for plant biomass-degrading microorganisms to thrive. Herein, the phylogenetic composition and lignocellulose-degrading capacity have been explored for the first time from a fosmid library dataset of Caatinga soil by sequence-based screening. A complex bacterial community dominated by Proteobacteria and Actinobacteria was unraveled. SEED subsystems-based annotations revealed a broad range of genes assigned to carbohydrate and aromatic compounds metabolism, indicating microbial ability to utilize plant-derived material. CAZy-based annotation identified 7275 genes encoding 37 glycoside hydrolases (GHs) families related to hydrolysis of cellulose, hemicellulose, oligosaccharides and other lignin-modifying enzymes. Taxonomic affiliation of genes showed high genetic potential of the phylum Acidobacteria for hemicellulose degradation, whereas Actinobacteria members appear to play an important role in celullose hydrolysis. Additionally, comparative analyses revealed greater GHs profile similarity among soils as compared to the digestive tract of animals capable of digesting plant biomass, particularly in the hemicellulases content. Combined results suggest a complex synergistic interaction of community members required for biomass degradation into fermentable sugars. This large repertoire of lignocellulolytic enzymes opens perspectives for mining potential candidates of biochemical catalysts for biofuels production from renewable resources and other environmental applications.