Microbiologia
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11840
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Item Arbuscular mycorrhizal fungal diversity in rhizosphere spores versus roots of an endangered endemic tree from Argentina: Is fungal diversity similar among forest disturbance types?(Applied Soil Ecology, 2016-02) Soteras, Florencia; Moreira, Bruno Coutinho; Grilli, Gabriel; Pastor, Nicolás; Mendes, Flávia Carneiro; Mendes, Daniele Ruela; Renison, Daniel; Kasuya, Maria Catarina Megumi; Souza, Francisco Adriano de; Becerra, AlejandraThe aim of this study was to compare the arbuscular mycorrhizal fungal (AMF) community of the rhizosphere and inside the roots of the perennial Polylepis australis tree. Three forest types differing in their structural complexity due to anthropogenic disturbances were chosen at three different sites at the high mountains of central Argentina. Rhizosphere spores and P. australis roots of four randomly selected trees were isolated from 36 soil samples, DNA was extracted and the 18S rDNA fragments were amplified by nested-PCR. The products were analyzed by DGGE and the bands were excised for sequencing. In total, 36 OTUs were defined from 56 DGGE bands successfully sequenced. Forest disturbance types showed similar communities of AMF, as rhizosphere spores and within the roots of P. australis. However, DGGE lustering showed mainly differences between rhizosphere spores and root-colonizing AMF. Members of Glomeraceae, Pacisporaceae, Acaulosporaceae and Gigasporaceae were shown in rhizosphere spore samples. Root samples showed only members of Acaulosporaceae and Gigasporaceae, which might be complementary in terms of soil resources exploration. The prevalence of the root system with their community of symbionts might explain the resilience of AMF soil communities to forests structural changes. This study presents evidence of a possible preference in the AMF–P. australis interaction.Item Bovicin HC5 and nisin reduce Staphylococcus aureus adhesion to polystyrene and change the hydrophobicity profile and Gibbs free energy of adhesion(International Journal of Food Microbiology, 2014-11-03) Pimentel-Filho, Natan de Jesus; Martins, Mayra Carla de Freitas; Nogueira, Guilherme Bicalho; Mantovani, Hilário Cuquetto; Vanetti, Maria Cristina DantasStaphylococcus aureus is an opportunistic pathogen often multidrug-resistant that not only causes a variety of human diseases, but also is able to survive on biotic and abiotic surfaces through biofilm communities. The best way to inhibit biofilm establishment is to prevent cell adhesion. In the present study, subinhibitory concentrations of the bacteriocins bovicin HC5 and nisin were tested for their capability to interfere with the adhesion of S. aureus to polystyrene. Subinhibitory dosages of the bacteriocins reduced cell adhesion and this occurred probably due to changes in the hydrophobicity of the bacterial cell and polystyrene surfaces. After treatment with bovicin HC5 and nisin, the surfaces became more hydrophilic and the free energy of adhesion (∆Gadhesion) between bacteria and the polystyrene surface was unfavorable. The transcriptional level of selected genes was assessed by RT-qPCR approach, revealing that the bacteriocins affected the expression of some important biofilm associated genes (icaD, fnbA, and clfB) and rnaIII, which is involved in the quorum sensing mechanism. The conditioning of food-contact surfaces with bacteriocins can be an innovative and powerful strategy to prevent biofilms in the food industry. The results are relevant for food safety as they indicate that bovicin HC5 and nisin can inhibit bacterial adhesion and consequent biofilm establishment, since cell adhesion precedes biofilm formation.Item Characterizing the microbiota across the gastrointestinal tract of a Brazilian Nelore steer(Veterinary Microbiology, 2013-02-16) Oliveira, Marcelo Nagem Valério de; Jewell, Kelsea A.; Freitas, Fernanda S.; Benjamin, Laércio A.; Tótola, Marcos R.; Borges, Arnaldo C.; Moraes, Célia A.; Suen, GarretThe gastrointestinal tracts (GIT) of herbivores harbor dense and diverse microbiota that has beneficial interactions with the host, particularly for agriculturally relevant animals like ruminants such as cattle. When assessing ruminant health, microbiological indicators are often derived from the rumen or feces. However, it is probable that ruminal and fecal microbiota do not reflect the microbial communities within the GIT of ruminants. To test this, we investigated the compartments of the GIT from a Brazilian Nelore steer and performed a 16S rRNA pyrosequencing analysis on the collected samples. Our results showed high intra-individual variation, with samples clustering according to their location in the GIT including the forestomach, small intestine, and large intestine. Although sequences related to the phyla Firmicutes and Bacteroidetes predominated all samples, there was a remarkable variation at the family level. Comparisons between the microbiota in the rumen, feces, and other GIT components showed distinct differences in microbial community. This work is the first intensive non-culture based GIT microbiota analysis for any ruminant and provides a framework for understanding how host microbiota impact the health of bovines.Item Misguided phylogenetic comparisons using DGGE excised bands may contaminate public sequence databases(Journal of Microbiological Methods, 2016-04-22) Pylro, Victor Satler; Morais, Daniel Kumazawa; Kalks, Karlos Henrique Martins; Roesch, Luiz Fernando Wurdig; Hirsch, Penny R.; Tótola, Marcos Rogério; Yotoko, KarlaControversy surrounding bacterial phylogenies has become one of the most important challenges for microbial ecology. Comparative analyses with nucleotide databases and phylogenetic reconstruction of the amplified 16S rRNA genes from DGGE (Denaturing Gradient Gel Electrophoresis) excised bands have been used by several researchers for the identification of organisms in complex samples. Here, we individually analyzed DGGE-excised 16S rRNA gene bands from 10 certified bacterial strains of different species, and demonstrated that this kind of approach can deliver erroneous outcomes to researchers, besides causing/emphasizing errors in public databases.Item Mobilisation of bacteria in a fine-grained residual soil by electrophoresis(Journal of Hazardous Materials, 2009-01-15) Rocha, Ulisses Nunes Da; Tótola, Marcos Rogério; Pessoa, Denise Maria Mano; Araruna Júnior, José Tavares; Neves, Júlio César Lima; Borges, Arnaldo ChaerAn investigation of electrokinetic bacterial mobilisation in a residual soil from gneiss is presented here. The experimental program aimed at assessing the efficacy of electrophoresis against the electro-osmotic flow to transport endospores of Bacillus subtilis LBBMA 155 and nitrogen-starved cells of Pseudomonas sp. LBBMA 81. Electrokinesis was performed on a low hydraulic reconstituted clayey soil column submitted to a 5 mA electrical current for 24 h. Cells were coccoid-shaped and characterised as possessing low surface hydrophobicity and less than 1 μm in diameter. Distribution coefficient for B. subtilis in the soil was between 16.8 and 19.9 times higher than that for Pseudomonas sp. Distribution coefficient for B. subtilis between eluate and anionic exchange column was 11.8 times higher than that for Pseudomonas sp. After the electrokinesis, it was shown that cells and endospores were distributed hyperbolically through the soil probe and moved against the electro-osmotic flow; however, endospores were transported throughout all soil core and starved cells only till half of its length. The higher transport efficiency of B. subtilis endospores was attributed to their higher negative charge on cell surface. These results demonstrate that electrokinesis can be used for bacteria transport in soils with low hydraulic conductivity, even against the electro-osmotic flow.