1,720,959 research outputs found
Polyextremotolerant Amylase Produced from Novel Enterococcus with Potpourri of Applications
No full textAmylolytic toluene-tolerant Enterococcus faecalis mercadA7 isolated from asbestos contaminated black soil from the Tokat province of Turkey was used for statistically optimized liquid phase fermentation to spawn elevated levels of amylase. Box Behnken technique of Response surface Methodology is followed to optimize three significant factors influencing Amylase production. To purify the amylase, ammonium sulfate fractionation, dialysis and gel filtration on Sephadex G-100 column chromatography were used. Submerged state fermentation at statistically optimized conditions augmented amylase production levels (8467 U ml(-1)) 8.74-fold compared to the conventional optimization. Purified amylase was found to possess specific activity of 1022 U mg(-1), optimal activity at pH 9 and 60 degrees C, 80% stable at 8.0-10.0 pH range and 90% stable at 45-75 degrees C for 1 h; with Km value of 8.06 mg ml(-1) and a V-max of 4.36 mmol h(-1) ml(-1), noteworthy stability up to 43% toluene, and upto 8% NaCl. High titers of Amylase produced from Enterococcus faecalis mercadA7 might find applications in copious industrial processes due to noteworthy stability of the cell-free purified enzyme at elevated temperatures, alkaline, and high toluene or salt concentrated environments
Catalytic Profile and Amylolytic Studies of Toluene-Tolerant Enterococcus faecalis str. nov mercadA7
No full textThis work pivots around screening a toluene-tolerant bacterium with concomitant alpha-amylase production ability. Eighteen alpha-amylase-producing bacterial strains were isolated from samples collected from Tokat province of Turkey among which strain A7 showed maximum alpha-amylase production titers (968 U/ml). The strain A7 was identified as Enterococcus faecalis mercadA7 (KX298857) with 54% GC content and 98% similarity to the closest strain, Enterococcus faecalis NBRC100480 through 16srRNA typing studies. The amylase production was improved 2.6-folds compared to the basal medium at optimal conditions recorded: 37 degrees C, pH 7.0, 18 h incubation, 1% v/v inoculum content and 20% toluene (carbon) supplementation. The amylase activity was demonstrated to increase upon exposure to toluene by a yet to be determined mechanism. The various growth kinetic parameters recorded are specific growth rate, mu(max) of 0.318 h(-1); constant, K-s 10.48 mg/ml; yield coefficient, Y-x/s of 0.1157 mg/g; and cell doubling time, t(d) of 51 min. The enzyme was partially purified with a threefold increase in specific activity; it was found to be active at pH 8 and 40 degrees C; stable from 30 to 50 degrees C and 7-10 pH range; maintaining stability up to 40% of toluene. The purified enzyme's maximum velocity, V-max of 3.33 mmol/h ml with constant, Km of 5 mg/ml were determined by Line Weaver Burke plot. Both Enterococcus faecalis mercadA7 and the purified alpha-amylase might find applications in several industrial processes due to the catalytic promiscuity triggered by the presence of toluene, and augmented stability of the cell-free purified enzyme as well as the organism to high alkaline/toluene levels
Redefining methods for augmenting lactic acid bacteria robustness and phenyllactic acid biocatalysis: Integration valorizes simplicity
No full textThe production of phenyllactic acid (PLA) has been reported by several researchers, but so far, no mention has been made of augmented PLA production using an orchestrated assembly of simple techniques integrated to improve lactic acid bacteria (LAB) metabolism for the same. This review summarizes sequentially tailoring LAB growth and metabolism for augmented PLA catalysis through several strategies like monitoring LAB sustenance by choosing appropriate starter PLA-producing LAB strains isolated from natural environments, with desirably fastidious growth rates, properties like acidification, proteolysis, bacteriophage-resistance, aromatic/texturing-features, etc.; entrapping chosen LAB strains in novel cryogels and/or co-cultivating two/more LAB strains to improve their biotransformation potential and promote growth dependency/sustainability; adopting adaptive evolution methods designed to improve LAB strains under selection pressure inducing desired phenotypes tolerant to stress factors like heat, salt, acid, and solvent; monitoring physico-chemical LAB fermentation factors like temperature, pH, dissolved oxygen content, enzymes, and cofactors for PLA biosynthesis; and modulating purification/downstream processes to extract substantial PLA yields. This review paper serves as a comprehensive preliminary guide that can evoke a strategic experimental plan to produce industrial-scale PLA yields using simple techniques orchestrated together in the pursuit of conserving time, effort, and resources
Lactic Acid Bacteria: Isolation–characterization Approaches and Industrial Applications
No full textThe current state-of-art research pertaining to lactic acid bacteria (LAB) calls for the screening and
isolation of robust LAB strains to achieve holistic exploitation of LAB and their metabolites of
marketable importance. Hence it is imperative to comprehend LAB sources, growth requisites,
isolation and characterization strategies necessary for featured cataloging and appropriate culturing.
This review comprehensively describes various growth media and biomasses used for supporting
LAB sustenance, assay procedures needed for the isolation and characterization of LAB strains,
and their application in diverse sectors. The various industrial patents and their summarized claims
about novel LAB strains isolated and identified, methods and media (used for detection/screening,
isolation, adaptation, culturing, preservation, growth improvement), the techniques and/or
methodologies supporting LAB fermentation, and applications of produced industrial metabolites
in various market scenarios are detaile
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Biosynthesis and Characterization of an Anticoagulant Chitinase from Fermented Wheat Bran & Shrimp Shells’ Substratum
Get PDFSolid state fermentation (SSF) of wheat bran coupled with shrimp shellfish waste Citrobacter freundii str. nov. haritD11 was optimized conventionally (112.43 U/gds) and statistically (124.73 U/gds). Chitinase was purified 4.24-fold with 31% yield and specific activity of 64.87 U/mg protein. The purified chitinase had a specific activity of 64.87 U/mg with optimal activity at pH 9 and temperature 45 ºC. The enzyme was stable at 8.0–9.5 pH range with 90% stability and between 45 °C – 60 °C for 1 hour. The Km value of the Citrobacter freundii haritD11 purified chitinase with swollen chitin (substrate) is 7.53 mg/mL with a Vmax of 2.27 mmol h−1mL−1. The purified chitinase was halotolerant showing maximum activity and stability up to 9% Sodium chloride, it also possessed potential antifungal and anticoagulant activity. This is the first report to date elucidating the production of halotolerant chitinase from wheat bran supplemented with shrimp shellfish waste using Citrobacter freundii haritD11 with notable tolerance to heavy metal ions, its application as an antifungal and anticoagulant agent.HIGHLIGHTS•Optimization of solid-state fermentation of Citrobacter freundii str. nov. haritD11.•The halotolerant chitinase was produced from wheat bran supplemented with shrimp shellfish waste.•The enzyme had notable tolerance to heavy metal ions.•Chitinase was purified 4.24-fold with 31% yield and specific activity of 64.87 U/mg.•The enzyme can be applied as an antifungal and anticoagulant agent
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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