Bacterial diversity in rhizosphere soil from Antarctic vascular plants of Admiralty Bay, maritime Antarctica

The Antarctic is a pristine environment that contributes to the maintenance of the global climate equilibrium. The harsh conditions of this habitat are fundamental to selecting those organisms able to survive in such an extreme habitat and able to support the relatively simple ecosystems. The DNA of the microbial community associated with the rhizospheres of Deschampsia antarctica Desv (Poaceae) and Colobanthus quitensis (Kunth) BartI (Caryophyllaceae), the only two native vascular plants that are found in Antarctic ecosystems, was evaluated using a 16S rRNA multiplex 454 pyrosequencing approach. This analysis revealed similar patterns of bacterial diversity between the two plant species from different locations, arguing against the hypothesis that there would be differences between the rhizosphere communities of different plants. Furthermore, the phylum distribution presented a peculiar pattern, with a bacterial community structure different from those reported of many other soils. Firmicutes was the most abundant phylum in almost all the analyzed samples, and there were high levels of anaerobic representatives. Also, some phyla that are dominant in most temperate and tropical soils, such as Acidobacteria, were rarely found in the analyzed samples. Analyzing all the sample libraries together, the predominant genera found were Bifidobacterium (phylum Actinobacteria), Arcobacter (phylum Proteobacteria) and Faecalibacterium (phylum Firmicutes). To the best of our knowledge, this is the first major bacterial sequencing effort of this kind of soil, and it revealed more than expected diversity within these rhizospheres of both maritime Antarctica vascular plants in Admiralty Bay, King George Island, which is part of the South Shetlands archipelago. The ISME Journal (2010) 4, 989-1001; doi:10.1038/ismej.2010.35; published online 1 April 2010

Bacterial and phytoplankton dynamics in a sub-tropical estuary

Heterotrophic bacterial and biomass, production, specific growth rates and growth efficiencies were studied in July 2001 and January 2002 during both spring and neap tides, along a tidal cycle, at three sites in a subtropical estuary. Major freshwater inputs located in the Northern region led to differences in both and bacterioplankton biomass and activity along the estuary. While in the Northern region is light-limited, with mean production (PP) between 1.1 and 1.9 mu g C l(-1) h(-1) and mean specific growth rates (PSG) between 0.14 and 0.16 d(-1), the Southern region registered values as high as 24.7 mu g C l(-1) h(-1) for PP and 2.45 d(-1) (mean PP between 3.4 and 7.3 mu g C l(-1) h(-1); mean PSG between 0.28 and 0.57 d(-1)). On the other hand, maximum bacterial production (BP: 63.8 mu g C l(-1) h(-1)) and specific growth rate (BSG: 32.26 d(-1)) were observed in the Northern region (mean BP between 3.4 and 12.8 mu g C l(-1) h(-1); mean BSG between 1.98 and 6.67 day(-1)). These bacterial activity rates are among the highest recorded rates in estuarine and coastal waters, indicating that this system can be highly heterotrophic, due to high loads of allochthonous carbon (mainly derived from mangrove forest). Our results also showed that, despite that BP rates usually exceeded PP, in the Southern region BP may be partially supported (similar to 45%) by PP, since a significant regression was observed between BP and PP (r = 0.455, P < 0.001).

Spatial and Temporal Variation of Archaeal, Bacterial and Fungal Communities in Agricultural Soils

Background: Soil microbial communities are in constant change at many different temporal and spatial scales. However, the importance of these changes to the turnover of the soil microbial communities has been rarely studied simultaneously in space and time. Methodology/Principal Findings: In this study, we explored the temporal and spatial responses of soil bacterial, archaeal and fungal beta-diversities to abiotic parameters. Taking into account data from a 3-year sampling period, we analyzed the abundances and community structures of Archaea, Bacteria and Fungi along with key soil chemical parameters. We questioned how these abiotic variables influence the turnover of bacterial, archaeal and fungal communities and how they impact the long-term patterns of changes of the aforementioned soil communities. Interestingly, we found that the bacterial and fungal b-diversities are quite stable over time, whereas archaeal diversity showed significantly higher fluctuations. These fluctuations were reflected in temporal turnover caused by soil management through addition of N-fertilizers. Conclusions: Our study showed that management practices applied to agricultural soils might not significantly affect the bacterial and fungal communities, but cause slow and long-term changes in the abundance and structure of the archaeal community. Moreover, the results suggest that, to different extents, abiotic and biotic factors determine the community assembly of archaeal, bacterial and fungal communities.

Bacterial leakage along the implant-abutment interface: culture and DNA Checkerboard hybridization analyses

Objective Bacterial species have been found harboring the internal surface of dental implants as consequence of their failed connections. The aim of the present study was to compare the detection frequency of bacterial leakage from human saliva through the implantabutment interface, under non-loading conditions, using either DNA Checkerboard or culture method. Materials and methods Thirty dental implants with hexagonal platforms were connected to pre-machined abutments according to the manufacturers specifications. The assemblies were individually incubated in human saliva under anaerobic conditions for 7 similar to days at 37 degrees C. Afterward, contents from the inner parts of the implants were collected and evaluated with either DNA Checkerboard (s similar to=similar to 15) or culture (n similar to=similar to 15). Subsequently, identification and quantitation of bacterial species from saliva and implants were carried out for the group evaluated with the DNA Checkerboard method. Results Both DNA Checkerboard and culture showed positive signals of bacterial leakage in 6 of the 15 evaluated samples. Capnocytophaga gingivalis and Streptococcus mutans were the most frequently detected species harboring the internal surface of the implants followed by Veillonella parvula. Conclusion Occurrence of bacterial leakage along the implantabutment interface is comparably detected with both DNA Checkerboard hybridization and conventional culture methods.

Characterization and in vitro evaluation of bacterial cellulose membranes functionalized with osteogenic growth peptide for bone tissue engineering

The aim of this study was to characterize the physicochemical properties of bacterial cellulose (BC) membranes functionalized with osteogenic growth peptide (OGP) and its C-terminal pentapeptide OGP[10-14], and to evaluate in vitro osteoinductive potential in early osteogenesis, besides, to evaluate cytotoxic, genotoxic and/or mutagenic effects. Peptide incorporation into the BC membranes did not change the morphology of BC nanofibers and BC crystallinity pattern. The characterization was complemented by Raman scattering, swelling ratio and mechanical tests. In vitro assays demonstrated no cytotoxic, genotoxic or mutagenic effects for any of the studied BC membranes. Culture with osteogenic cells revealed no difference in cell morphology among all the membranes tested. Cell viability/proliferation, total protein content, alkaline phosphatase activity and mineralization assays indicated that BC-OGP membranes enabled the highest development of the osteoblastic phenotype in vitro. In conclusion, the negative results of cytotoxicity, genotoxicity and mutagenicity indicated that all the membranes can be employed for medical supplies, mainly in bone tissue engineering/regeneration, due to their osteoinductive properties.

INTERSPECIFIC VARIATION OF THE BACTERIAL COMMUNITY STRUCTURE IN THE PHYLLOSPHERE OF THE THREE MAJOR PLANT COMPONENTS OF MANGROVE FORESTS

Mangrove forests encompass a group of trees species that inhabit the intertidal zones, where soil is characterized by the high salinity and low availability of oxygen. The phyllosphere of these trees represent the habitat provided on the aboveground parts of plants, supporting in a global scale, a large and complex microbial community. The structure of phyllosphere communities reflects immigration, survival and growth of microbial colonizers, which is influenced by numerous environmental factors in addition to leaf physical and chemical properties. Here, a combination of culture-base methods with PCR-DGGE was applied to test whether local or plant specific factors shape the bacterial community of the phyllosphere from three plant species (Avicenia shaueriana, Laguncularia racemosa and Rhizophora mangle), found in two mangroves. The number of bacteria in the phyllosphere of these plants varied between 3.62 x 10(4) in A. schaeriana and 6.26 x 10(3) in R. mangle. The results obtained by PCR-DGGE and isolation approaches were congruent and demonstrated that each plant species harbor specific bacterial communities in their leaves surfaces. Moreover, the ordination of environmental factors (mangrove and plant species), by redundancy analysis (RDA), also indicated that the selection exerted by plant species is higher than mangrove location on bacterial communities at phyllosphere.

In Vitro Analysis of Bacterial Morphology by Atomic Force Microscopy of Low Level Laser Therapy 660, 830 and 904 nm

Objective: The objective of this study was to analyze the bacterial morphology by atomic force microscopy (AFM) after the application of low-level laser therapy (LLLT) in in vitro culture of Staphylococcus aureus ATCC 29213. Background data: Infections caused by S. aureus are among the highest occurring in hospitals and can often colonize pressure ulcers. LLLT is among the methods used to accelerate the healing of ulcers. However, there is no consensus on its effect on bacteria. Materials and methods: After being cultivated and seeded, the cultures were irradiated using wavelengths of 660, 830, and 904 nm at fluences of 0, 1, 2, 3, 4, 5, and 16 J/cm(2). Viable cells of S. aureus strain were counted after 24 h incubation. To analyze the occurrence of morphological changes, the topographical measurement of bacterial cells was analyzed using the AFM. Results: The overall assessment revealed that the laser irradiation reduced the S. aureus growth using 830 and 904 nm wavelengths; the latter with the greatest inhibition of the colony-forming units (CFU/mL) (331.1 +/- 38.19 and 137.38 +/- 21.72). Specifically with 660 nm, the statistical difference occurred only at a fluence of 3 J/cm(2). Topographical analysis showed small changes in morphological conformity of the samples tested. Conclusions: LLLT reduced the growth of S. aureus with 830 and 904 nm wavelengths, particularly with 904 nm at a fluence of 3 J/cm(2), where the greatest topographical changes of the cell structure occurred.

Effectiveness of the association of dexamethasone with antibiotic therapy in pediatric patients with bacterial meningitis

Effectiveness of the association of dexamethasone with antibiotic therapy in pediatric patients with bacterial meningitis Objective: To evaluate the efficacy of the association of corticosteroids and the standard treatment of bacterial meningitis in pediatric patients. Methods: A systematic review of the literature was conducted through the MEDLINE database. Only randomized controlled trials comparing dexamethasone with placebo in the treatment of pediatric patients with bacterial meningitis were included. Results: Eight articles met the inclusion criteria and were selected for analysis. There were no difference in mortality (p = 0.86), and incidence of neurological (p = 0.41) and auditory (p = 0.48) sequelae between the groups. Conclusion: There are no benefits in associating corticosteroids with the standard treatment of bacterial meningitis in pediatric patients.

Transparent bacterial cellulose-boehmite-epoxi-siloxane nanocomposites

Organic-inorganic composite membranes were prepared from membranes of the bio-polymer bacterial cellulose (BC) and organic-inorganic sal composed of nanoparticulate boehmite and epoxi modified siloxane. Bacterial cellulose membranes are obtained in a highly hydrated state (1% cellulose and 99% cellulose) from cultures of Gluconacetobacter xylinus and could be used in the never-dried or in the dried state. Depending on the use of dried or never-dried BC membranes two main kinds of composites were obtained. In the first one dried BC membranes coated with the hybrid sol have lead to transparent membranes displaying a hi-phase structure where the two components could be easily distinguished, with individual structures preserved. A decrease was observed for tensile strength (50.5 MPa) and Young's Modulus (2.8 GPa) when compared to pure BC membrane (112.5 MPa and 12.7 GPa). Elongation at break was observed to increase (2.5% against 1.5% observed for BC). When never-dried BC membranes were used transparent membranes were also obtained, however an improvement was observed for mechanical properties (tensile strength - 116 MPa and Young's Modulus - 13.7 GPa). A lower value was obtained for the elongation at break (1.3%). In the last case the interaction between the two-phases lead to changes in the cellulose crystallinity as shown by X rays diffraction results. Multifunctional transparent membranes displaying the cellulose structure in one side and the boehmite-siloxane structure at the opposite face could find special applications in opto-electronics or biomedical areas taking advantage of the different chemical nature of the two components. (C) 2012 Elsevier Ltd. All rights reserved.

Endophthalmitis: A Rare but Devastating Metastatic Bacterial Complication of Hemodialysis Catheter-Related Sepsis

There are many infectious complications related to vascular access in patients undergoing maintenance hemodialysis. We report two cases of endophthalmitis as a metastatic infection associated with a tunneled catheter and a temporary dual lumen catheter. Both patients were diabetic. A 61-year-old female on maintenance hemodialysis by a jugular tunnelized catheter during the past year was receiving parenteral antibiotics for catheter salvage due to fever episodes in the last 3 months. She was admitted to the hospital presenting pain, proptosis, conjunctival hyperemia, corneal infiltrate, and visual acuity of no light perception (NLP). A 51-year-old male recently undergoing hemodialysis by a temporary dual lumen catheter presented fever. His catheter was removed, but he was admitted to the hospital presenting fever, decreased vision, edema, and pain in his left eye. On examination, eyelid edema, conjunctival hyperemia, purulent secretion, hypopyon in the pupils, and visual acuity of NLP were verified. A diagnosis of endogenous endophthalmitis was made in both patients on clinical grounds and computed tomography. Evisceration of the left eye was the first option of treatment for both patients due to poor vision. Cultures of the eviscerated ocular globes showed Staphylococcus hemolyticus and Staphylococcus aureus, respectively. After evisceration, both patients received treatment, had a good outcome, and were discharged to continue their hemodialysis program. Metastatic bacterial endophthalmitis is a rare complication of dialysis catheter-related bacteremia. When suspected, urgent ophthalmologic evaluation and treatment are needed to reduce the risk of losing vision in the affected eye.

Influence of Growth Media and Temperature on Bacterial Adhesion to Polystyrene Surfaces

Bacterial adhesion to inert surfaces is a complex process influenced by environmental conditions. In this work, the influence of growth medium and temperature on the adhesion of Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, Micrococcus luteus and Listeria monocytogenes to polystyrene surfaces was studied. Most bacteria demonstrated the highest adhesion when cultured in TSYEA, except S. marcescens, which showed to be positively influenced by the pigment production, favored in poor nutrient media (lactose and peptone agar). P. aeruginosa adhesion to polystyrene increased at low temperatures whatever the medium used. The culture medium influenced the surface properties of the bacteria as assessed by the MATS test.

Establishment of the bacterial fecal community during the first month of life in Brazilian newborns

OBJECTIVE: The establishment of the intestinal microbiota in newborns is a critical period with possible long-term consequences for human health. In this research, the development of the fecal microbiota of a group of exclusively breastfed neonates living in low socio-economic conditions in the city of Sao Paulo, Brazil, during the first month of life, was studied. METHODS: Fecal samples were collected from ten neonates on the second, seventh, and 30th days after birth. One of the neonates underwent antibiotic therapy. Molecular techniques were used for analysis; DNA was extracted from the samples, and 16S rRNA libraries were sequenced and phylogenetically analyzed after construction. A real-time polymerase chain reaction (PCR) was performed on the samples taken from the 30th day to amplify DNA from Bifidobacterium sp. RESULTS: The primary phylogenetic groups identified in the samples were Escherichia and Clostridium. Staphylococcus was identified at a low rate. Bifidobacterium sp. was detected in all of the samples collected on the 30th day. In the child who received antibiotics, a reduction in anaerobes and Escherichia, which was associated with an overgrowth of Klebsiella, was observed throughout the experimental period. CONCLUSION: The observed pattern of Escherichia predominance and reduced Staphylococcus colonization is in contrast with the patterns observed in neonates living in developed countries.

Performance and composition of bacterial communities in anaerobic fluidized bed reactors for hydrogen production: Effects of organic loading rate and alkalinity

This study evaluated the effects of the organic loading rate (OLR) and pH buffer addition on hydrogen production in two anaerobic fluidized bed reactors (AFBRs) operated simultaneously. The AFBRs were fed with glucose, and expanded clay was used as support material. The reactors were operated at a temperature of 30 degrees C, without the addition of a buffer (AFBR1) and with the addition of a pH buffer (AFBR2, sodium bicarbonate) for OLRs ranging from 19.0 to 140.6 kg COD m(-3) d(-1) (COD: chemical oxygen demand). The maximum hydrogen yields for AFBR1 and AFBR2 were 2.45 and 1.90 mol H-2 mol(-1) glucose (OLR of 84.3 kg COD m(-3) d(-1)), respectively. The highest hydrogen production rates were 0.95 and 0.76 L h(-1) L-1 for AFBR1 and AFBR2 (OLR of 140.6 kg COD m(-3) d(-1)), respectively. The operating conditions in AFBR1 favored the presence of such bacteria as Clostridium, while the bacteria in AFBR2 included Clostridium, Enterobacter, Klebsiella, Veillonellaceae, Chryseobacterium, Sporolactobacillus, and Burkholderiaceae. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Evaluation of bacterial infections in organ transplantation

Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo

Comparative Studies of the (Anti) Mutagenicity of Baccharis dracunculifolia and Artepillin C by the Bacterial Reverse Mutation Test

Baccharis dracunculifolia is a plant native from Brazil, commonly known as 'Alecrim-do-campo' and 'Vassoura' and used in alternative medicine for the treatment of inflammation, hepatic disorders and stomach ulcers. Previous studies reported that artepillin C (ArtC, 3-{4-hydroxy-3,5-di(3-methyl-2-butenyl)phenyl}-2(E)-propenoic acid), is the main compound of interest in the leaves. This study was undertaken to assess the mutagenic effect of the ethyl acetate extract of B. dracunculifolia leaves (Bd-EAE: 11.4-182.8 mu g/plate) and ArtC (0.69-10.99 mu g/plate) by the Ames test using Salmonella typhimurium strains TA98, TA97a, TA100 and TA102, and to compare the protective effects of Bd-EAE and ArtC against the mutagenicity of a variety of direct and indirect acting mutagens such as 4-nitro-O-phenylenediamine, sodium azide, mitomycin C, benzo[a]pyrene, aflatoxin B1, 2-aminoanthracene and 2-aminofluorene. The mutagenicity test showed that Bd-EAE and ArtC did not induce an increase in the number of revertant colonies indicating absence of mutagenic activity. ArtC showed a similar antimutagenic effect to that of Bd-EAE in some strains of S. typhimurium, demonstrating that the antimutagenic activity of Bd-EAE can be partially attributed to ArtC. The present results showed that the protective effect of whole plant extracts is due to the combined and synergistic effects of a complex mixture of phytochemicals, the total activity of which may result in health benefits.