1,720,962 research outputs found
Electroactivity of weak electricigen Bacillus subtilis biofilms in solution containing deep eutectic solvent components
Full text linkBacillus subtilis is a Gram-positive, spore-forming bacterium with a versatile and adaptable metabolism, which makes it a viable cell factory for microbial production. Electroactivity has recently been identified as a cellular characteristic linked with the metabolic activity of B. subtilis. The enhancement of B. subtilis electroactivity can positively enhance bioproduction of high-added value metabolites under electrofermentative conditions. Here, we explored the use of deep eutectic solvents (DESs) and DES components as biocompatible nutrient additives for enhancing electroactivity of B. subtilis. The strongest electroactivity was obtained in an aqueous choline chloride: glycerol (1:2 mol mol-1) eutectic mixture. At low concentration (50-500 mM), this mixture induced a pseudodiauxic increase in planktonic growth and increased biofilm formation, likely due to a nutritional and osmoprotectant effect. Similarities in electroactivity enhancements of choline chloride-based eutectic mixtures and quinone redox metabolism in B. subtilis were detected using high performance liquid chromatography and differential pulse voltammetry. Results show that choline chloride-based aqueous eutectic mixtures can enhance biomass and productivity in biofilm-based electrofermentation. However, the specific mechanism needs to be fully elucidated
ELECTROANALYSIS OF MICROBIAL BIOFILMS AND ANTIBIOFILM DRUG TESTING
No full textMicrobial biofilms are responsible for about 80% of infectious diseases in humans, resulting in high morbidity and mortality rates. Biofilm confers protection to the microbial cells from stressors, including antimicrobial treatments. Biofilms are more difficult to remove/kill, thus, contributing to antimicrobial resistance phenomenon. Unfortunately, existing methodologies routinely employed for microbial biofilms and evaluation of anti-biofilm compounds are flawed with varying limitations. Therefore, an urgent need for the design/development and adoption of new diagnostic platforms is exigent. Additionally, the need for new therapeutic options cannot be overemphasized.
In this work, a bioelectrochemical platform that uses simple, low-cost, and commercially available screen-printed electrodes was implemented for real-time evaluation of selected antimicrobials against clinically relevant biofilm-forming species. We also adopted a drug repurposing strategy against a model resistant bacterial strain using the developed bioelectrochemical platform. Finally, attempt was made to detect a model fungal pathogen in human urine samples also via the developed platform.
In general, both biochemical and electroanalytic methods suggests that complete inhibition of biofilm formation would require concentrations higher than that needed for planktonic cells. Further optimization of the methodology on C. albicans biofilms indicated that the antifungal activity of the tested compounds is in the order of complex Ag3>Amphotericin B>Fluconazole, while the conventional XTT indicated the order of Amphotericin B > Fluconazole >complex Ag3. This variability further reiterates the necessity for a multi-method approach to validate the antibiofilm efficacy of any compound. However, this study demonstrated, for the first time, the real-time antibiofilm assessment of selected antimicrobials using electroanalytical approach and offers consistent findings as early as 10 h following inoculatio
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Electrofermentation increases concentration of poly γ‐glutamic acid in Bacillus subtilis biofilms
Full text linkAbstract Fluctuations in redox conditions in bioprocesses can alter the end‐products, reduce their concentration, and lengthen the process time. Electrofermentation enables rapid metabolic modulation of biosynthesis and allows control of redox imbalances in biofilm‐based fermentation processes. In this study, electrofermentation is used to boost the production of the bacterial biopolymer poly‐γ‐glutamic acid (γ‐PGA) from Bacillus subtilis ATCC 6051. When compared to control experiments (3.3 ± 0.99 g L−1), the application of an electrode potential E = 0.4 V versus Ag/AgCl results in a more than two‐fold increase in the production of γ‐PGA (9.13 ± 1.4 g L−1). Using an engineered B. subtilis strain, in which γ‐PGA production is driven by isopropyl β‐d‐1‐thiogalactopyranoside, electrofermentation improves polymer concentrations from 15.4 ± 1.5 to 23.1 ± 1.6 versus g L−1. These results confirm that electrofermentation conditions can be adopted to increase the concentration of γ‐PGA and perhaps other extracellular biopolymers in industrial strains
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