Wiley
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Power output and columbic efficiencies from biofilms of <i>Geobacter sulfurreducens</i> comparable to mixed community microbial fuel cells Summary It has been previously noted that mixed communities typically produce more power in microbial fuel cells than pure cultures. If true, this has important implications for the design of microbial fuel cells and for studying the process of electron transfer on anode biofilms. To further evaluate this, Geobacter sulfurreducens was grown with acetate as fuel in a continuous flow ‘ministack’ system in which the carbon cloth anode and cathode were positioned in close proximity, and the cation‐selective membrane surface area was maximized in order to overcome some of the electrochemical limitations that were inherent in fuel cells previously employed for the study of pure cultures. Reducing the size of the anode in order to eliminate cathode limitation resulted in maximum current and power densities per m2 of anode surface of 4.56 A m−2 and 1.88 W m−2 respectively. Electron recovery as current from acetate oxidation was c . 100% when oxygen diffusion into the system was minimized. This performance is comparable to the highest levels previously reported for mixed communities in similar microbial fuel cells and slightly higher than the power output of an anaerobic sludge inoculum in the same ministack system. Minimizing the volume of the anode chamber yielded a volumetric power density of 2.15 kW m−3 , which is the highest power density per volume yet reported for a microbial fuel cell. Geobacter sulfurreducens formed relatively uniform biofilms 3–18 μm thick on the carbon cloth anodes. When graphite sticks served as the anode, the current density (3.10 A m−2 ) was somewhat less than with the carbon cloth anodes, but the biofilms were thicker (c . 50 μm) with a more complex pillar and channel structure. These results suggest that the previously observed disparity in power production in pure and mixed culture microbial fuel cell systems can be attributed more to differences in the fuel cell designs than to any inherent superior capability of mixed cultures to produce more power than pure cultures.
Wiley - Tập 10 Số 10 - Trang 2505-2514 - 2008
Diversity, distribution and sources of bacteria in residential kitchens Summary Bacteria readily colonize kitchen surfaces, and the exchange of microbes between humans and the kitchen environment can impact human health. However, we have a limited understanding of the overall diversity of these communities, how they differ across surfaces and sources of bacteria to kitchen surfaces. Here we used high‐throughput sequencing of the 16S rRNA gene to explore biogeographical patterns of bacteria across > 80 surfaces within the kitchens of each of four households. In total, 34 bacterial and two archaeal phyla were identified, with most sequences belonging to the A ctinobacteriaB acteroidetesF irmicutesP roteobacteriaG ram‐negative lineages. Community composition was influenced by conditions on individual surfaces, usage patterns and dispersal from source environments. Human skin was the primary source of bacteria across all kitchen surfaces, with contributions from food and faucet water dominating in a few specific locations. This study demonstrates that diverse bacterial communities are widely distributed in residential kitchens and that the composition of these communities is often predictable. These results also illustrate the ease with which human‐ and food‐associated bacteria can be transferred in residential settings to kitchen surfaces.
Wiley - Tập 15 Số 2 - Trang 588-596 - 2013
Gliotoxin – bane or boon? Summary Gliotoxin (GT ) is the most important epidithiodioxopiperazine (ETP )‐type fungal toxin. GT was originally isolated from T richoderma species as an antibiotic substance involved in biological control of plant pathogenic fungi. A few isolates of GT ‐producing T richoderma virens are commercially marketed for biological control and widely used in agriculture. Furthermore, GT is long known as an immunosuppressive agent and also reported to have anti‐tumour properties. However, recent publications suggest that GT is a virulence determinant of the human pathogen A spergillus fumigatus . This compound is thus important on several counts – it has medicinal properties, is a pathogenicity determinant, is a potential diagnostic marker and is important in biological crop protection. The present article addresses this paradox and the ecological role of GT . We discuss the function of GT as defence molecule, the role in aspergillosis and suggest solutions for safe application of T richoderma ‐based biofungicides.
Wiley - Tập 18 Số 4 - Trang 1096-1109 - 2016
Towards a taxonomy of<i>Bacteria</i>and<i>Archaea</i>based on interactive and cumulative data repositories Summary Taxonomy in the second decade of the 21st century is benefiting from technological advances in molecular microbiology, especially those related to genomics. Gene and genome databases are significantly increasing due to intense research activities in the field of molecular ecology and genomics. Taxa, and especially species, are tailored by means of the recognition of a phylogenetic, genomic and phenotypic coherence that reveal their uniqueness in the classification schema. Phylogenetic coherence is mainly revealed by means of 16S rRNA gene analyses for which curated databases such as EzTaxon and LTP provide a valuable tool for tree reconstruction to taxonomy users. On the other hand,in silico full or partial genomic sequence comparisons are called on to substitute cumbersome techniques such as DNA–DNA hybridization (DDH) to genomically circumscribe species. DDH similarity values around 70% would be equivalent to ANI values of 96%. Finally, finding an exclusive phenotypic property for the taxa to be classified is of paramount relevance to producing an operative and predictive classification system. The current methods used for taxonomic classification require significant laboratory experimentation, and generally will not produce interactive databases. The new high‐throughput metabolomic technologies, such as ICR‐FT and MALDI‐TOF mass spectrometry methods, open the door to the construction of metabolic databases for taxonomic purposes. It is to be foreseen that, in the future, taxonomists will benefit significantly from public databases speeding up the classification process. However, serious effort will be needed to harmonize them and to prevent inaccurate material.
Wiley - Tập 14 Số 2 - Trang 318-334 - 2012
Taxonomic resolution, ecotypes and the biogeography of <i>Prochlorococcus</i> Summary In order to expand our understanding of the diversity and biogeography of Prochlorococcus ribotypes, we PCR‐amplified, cloned and sequenced the 16S/23S rRNA ITS region from sites in the Atlantic and Pacific oceans. Ninety‐three per cent of the ITS sequences could be assigned to existing Prochlorococcus clades, although many novel subclades were detected. We assigned the sequences to operational taxonomic units using a graduated scale of sequence identity from 80% to 99.5% and correlated Prochlorococcus diversity with respect to environmental variables and dispersal time between the sites. Dispersal time was estimated using a global ocean circulation model. The significance of specific environmental variables was dependent on the degree of sequence identity used to define a taxon: light correlates with broad‐scale diversity (90% cut‐off), temperature with intermediate scale (95%) whereas no correlation with phosphate was observed. Community structure was correlated with dispersal time between sample sites only when taxa were defined using the finest sequence similarity cut‐off. Surprisingly, the concentration of nitrate, which cannot be used as N source by the Prochlorococcus strains in culture, explains some variation in community structure for some definitions of taxa. This study suggests that the spatial distribution of Prochlorococcus ecotypes is shaped by a hierarchy of environmental factors as well dispersal limitation.
Wiley - Tập 11 Số 4 - Trang 823-832 - 2009
Heavy use of prophylactic antibiotics in aquaculture: a growing problem for human and animal health and for the environment Summary The accelerated growth of finfish aquaculture has resulted in a series of developments detrimental to the environment and human health. The latter is illustrated by the widespread and unrestricted use of prophylactic antibiotics in this industry, especially in developing countries, to forestall bacterial infections resulting from sanitary shortcomings in fish rearing. The use of a wide variety of antibiotics in large amounts, including non‐biodegradable antibiotics useful in human medicine, ensures that they remain in the aquatic environment, exerting their selective pressure for long periods of time. This process has resulted in the emergence of antibiotic‐resistant bacteria in aquaculture environments, in the increase of antibiotic resistance in fish pathogens, in the transfer of these resistance determinants to bacteria of land animals and to human pathogens, and in alterations of the bacterial flora both in sediments and in the water column. The use of large amounts of antibiotics that have to be mixed with fish food also creates problems for industrial health and increases the opportunities for the presence of residual antibiotics in fish meat and fish products. Thus, it appears that global efforts are needed to promote more judicious use of prophylactic antibiotics in aquaculture as accumulating evidence indicates that unrestricted use is detrimental to fish, terrestrial animals, and human health and the environment.
Wiley - Tập 8 Số 7 - Trang 1137-1144 - 2006
Core sediment bacteria drive community response to anthropogenic contamination over multiple environmental gradients Summary In this study, 454 pyrosequencing of the 16S rRNA gene was used to investigate sediment bacterial community response to contaminant disturbance across six estuaries with differing levels of ‘modification’. We observed a significant influence of metal and polycyclic aromatic hydrocarbon contaminants in shaping bacterial community composition, structure and diversity, with metals being the more influential contaminant. An abundant and pervasive ‘core’ set of bacteria found in every sample were largely responsible for mediating community response to contamination. These 13 core operational taxonomic units were mostly comprised of G amma‐D elta‐, A lphaproteobacteriaA cidobacteria
Wiley - Tập 15 Số 9 - Trang 2517-2531 - 2013
Infection‐competent monkeypox virus contamination identified in domestic settings following an imported case of monkeypox into the <scp>UK</scp> Abstract An imported case of monkeypox was diagnosed in December 2019 in a traveller returning from Nigeria to the UK. Subsequently, environmental sampling was performed at two adjoining single‐room residences occupied by the patient and their sibling. Monkeypox virus DNA was identified in multiple locations throughout both properties, and monkeypox virus was isolated from several samples 3 days after the patient was last in these locations. Positive samples were identified following the use of both vacuum and surface sampling techniques; these methodologies allowed for environmental analysis of potentially contaminated porous and non‐porous surfaces via real‐time quantitative reverse transcriptase PCR analysis in addition to viral isolation to confirm the presence of infection‐competent virus. This report confirms the potential for infection‐competent monkeypox virus to be recovered in environmental settings associated with known positive cases and the necessity for rapid environmental assessment to reduce potential exposure to close contacts and the general public. The methods adopted in this investigation may be used for future confirmed cases of monkeypox in order to establish levels of contamination, confirm the presence of infection‐competent material and to identify locations requiring additional cleaning.
Wiley - Tập 24 Số 10 - Trang 4561-4569 - 2022
Effects of environmental temperature on the gut microbial communities of tadpoles Summary Numerous studies have investigated the effects of diet, phylogeny and immune status on the gut microbial communities of animals. Most of these studies are conducted on endotherms, especially mammals, which maintain constant body temperature in the face of environmental temperature variability. However, the majority of animals and vertebrates are ectotherms, which often experience fluctuations in body temperature as a result of their environment. While there have been several studies investigating the gut microbial diversity of ectotherms, we lack an understanding of how environmental temperature affects these communities. Here, we used high‐throughput sequencing to inventory the gut microbial communities of tadpoles exposed to cool (18°C) or warm (28°C) temperature treatments. We found that temperature significantly impacted the community structure and membership of the tadpole gut. Specifically, tadpoles in the warm treatment exhibited higher abundances of the phylum Planctomycetes and the genus Mycobacterium . These results may be due to the direct effects of temperature, or mediated through changes in host physiology. Given that environmental temperatures are expected to increase due to global climate change, understanding the effects of temperature on the diversity and function of gut microbial communities is critical.
Wiley - Tập 18 Số 5 - Trang 1561-1565 - 2016
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