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Microbial transformation of Astragalus sapogenins using Cunninghamella blakesleeana NRRL 1369 and Glomerella fusarioides ATCC 9552
No full textThe microbial transformation of Astragalus sp. derived sapogenins, namely cycloastragenol, astragenol and cyclocanthogenol, by Cunninghamella blakesleeana NRRL 1369 and Glomerella fusarioides ATCC 9552 were investigated. The unique enzyme system of both fungi resulted hydroxylation, cyclization, dehydrogenation and oxidation reactions. Structures of the new metabolites were elucidated by 1-D (H-1, C-13, NOESY), 2-D NMR (DQF-COSY, HMBC, HMQC, NOESY) and HR-MS analyses. (C) 2015 Elsevier B.V. All rights reserved
Multi-objective optimization of a novel crude lipase-catalyzed fatty acid methyl ester (FAME) production using low-order polynomial and Kriging models
No full textIn this paper, conventional response surface methodology (RSM) based on low-order polynomials and an alternative Kriging-based method are used for the model-based single and multi-objective optimization of fatty-acid methyl ester (FAME) production catalyzed by a novel crude lipase from the yeast Cryptococcus diffluens (D44). The coefficient of determination for the two modeling approaches was calculated as 0.97 for the Kriging method, and 0.86 for RSM; showing a more reliable representation of experimental data by Kriging. Both models were used to perform single (maximizing FAME titer and temporal productivity separately) and multi-objective (maximizing FAME titer and temporal productivity simultaneously) optimizations of four important operating conditions (reaction time and temperature; amount of crude enzyme; and volume of methanol used). In all cases, the highest temperature considered (60 degrees C) gave the best results. A reduction of reaction time in half was seen to be necessary to achieve optimum productivity compared to titer, when the two objectives were considered separately. The observed trade-off between the two objectives was quantified via multi-objective optimization using Pareto-front analysis
Assessment of hazelnut husk as a lignocellulosic feedstock for the production of fermentable sugars and lignocellulolytic enzymes
No full textThe present work focuses firstly on the evaluation of the effect of laccase on enzymatic hydrolysis of hazelnut husk which is one of the most abundant lignocellulosic agricultural residues generated in Turkey. In this respect, the co-enzymatic treatment of hazelnut husk by cellulase and laccase, without a conventional pretreatment step is evaluated. Using 2.75 FPU/g substrate (40 g/L substrate) and a ratio of 131 laccase U/FPU achieved the highest reducing sugars concentration. Gas chromatography mass spectrometry confirmed that the hydrolysate was composed of glucose, xylose, mannose, arabinose and galactose. The inclusion of laccase in the enzyme mixture [carboxymethyl cellulase (CMCase) and beta-glucosidase] increased the final glucose content of the reducing sugars from 20 to 50%. Therefore, a very significant increase in glucose content of the final reducing sugars concentration was obtained by laccase addition. Furthermore, the production of cellulases and laccase by Pycnoporus sanguineus DSM 3024 using hazelnut husk as substrate was also investigated. Among the hazelnut husk concentrations tested (1.5, 6, 12, 18 g/L), the highest CMCase concentration was obtained using 12 g/L husk concentration on the 10th day of fermentation. Besides CMCase, P. sanguineus DSM 3024 produced beta-glucosidase and laccase using hazelnut husk as carbon source. In addition to CMCase and b-glucosidase, the highest laccase activity measured was 2240 +/- 98 U/L (8.89 +/- 0.39 U/mg). To the best of our knowledge, this is the first study to report hazelnut husk hydrolysis in the absence of pretreatment procedures
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
Sikloartan grubu siklokantogenol ve astragenol saponinlerinin mikrobiyal biyotransformasyonu
No full textMikroorganizmalar tarafından çok çeşitli reaksiyonlar katalizlenmektedir. Mikrobiyal transformasyon, bazı biyolojik aktif ürünlerin yapılarının modifiye edilmesi ve doğal ürün metabolizmasının çalışılması açısından ekonomik ve ekolojik olarak uygulanabilir bir teknoloji olarak görülmektedir. Bu tezin amacı, farmakolojik etkilerinden dolayı son günlerde önemli hale gelmiş Astragalus cinsi sikloartan grubu sapogenollerinden olan siklokantogenol (SKG) ve astragenol (AG) üzerinde mikrobiyal transformasyon çalışmaları gerçekleştirmek, yeni türevler elde etmek ve sitotoksisitelerini incelemektir. Bu çalışmada, uygun besin ortamları kullanılarak Nocardia sp. NRRL 5646 bakterisi ile Cunninghamella blakesleeana ATCC 8688a (NRRL 1369) ve Glomerella fusarioides ATCC 9552 fungusları üretildikten sonra, organizmaların katalizlediği reaksiyonların sonucunda oluşan biyotransformasyon ürünleri incelenmiş ve karakterizasyonları yapılmıştır. Son olarak, oluşan yeni metabolitler, sitotoksisitelerinin belirlenmesi için MTT testine tabi tutulmuştur. C. blakesleeana fungusunun SKG ile gerçekleştirilen biyotransformasyon çalışması, C-11 pozisyonunda primer alkol içeren bir major molekülün eldesi ile sonuçlanırken, aynı fungusun AG ile yapılan biyotransformasyon çalışması sonucunda 3 farklı metabolit elde edilmiştir. Major molekülün C-12 pozisyonunda hidroksil grubu içerdiği belirlenmiştir. Diğer iki molekül 10,11 epoksi halkasına sahip olduğu bulunmuştur ve bunlardan birinin ayrıca C-6 pozisyonunda hidroksil grubu yerine keton grubu taşıdığı saptanmıştır. G. fusarioides fungusunun SKG ile yapılan biyotransformasyon çalışması sonucunda Baeyer-Villiger tipi oksidasyon sonrası 3,4-seko ürün oluşmuştur. Sonuç olarak beş biyotransformasyon ürünü elde edilmiştir ve bu bileşikler doğa ve literatür için yenidir. Ayrıca biyotransformasyon ürünleri kanser hücre hatlarına karşı anlamlı sitotoksisite göstermemiştir (>100 μg/mL)
Multi-objective optimization at a crude novel lipase catalyzed fame production: kriging as an alternative to rsm
No full textBiyodizel özellikle transport sektörü açısından petrol kaynaklı dizel yakıtlara yenilenebilir ve potansiyel olarak sürdürülebilir bir alternatiftir. Biyodizel, ham, rafine veya atık yağlar ile hayvansal yağlar gibi çeşitli hammaddeler kullanılarak, katalitik olmayan ısıl yöntemler, homojen ya da heterojen kimyasal dönüşümler ve biyokatalitik dönüşümler ile üretilebilmektedir. Atık pişirme yağından elde edilen biyokatalitik biyodizel üretiminin ticari olarak uygulanabilirliği, hammaddedeki trigliseritlerin transesterifikasyonunu ve serbet yağ asitlerinin esterifikasyonunu katalizleyen lokal ve ekonomik olarak üretilme potansiyeli olan yeni lipazların mevcudiyetine bağlıdır. Bu açıdan, farklı kaynaklardan değişik özelliklere sahip farklı lipazların taranması, seçilmesi ve geliştirilmesi, lipaz katalizli biyodizel üretiminin cazip hale gelmesinde temel bir görevdir. Yeni lipazlar için erken değerlendirme deneyleri, değişen reaksiyon sıcaklığı, alkil reseptör substrat mol oranı ve enzim miktarı altında zamana bağlı değişimleri gözlemlemek için uygulanmaktadır. Bu erken dönem deneylerinden elde edilen ön veriler, yeni lipazların hızlı ve etkili bir şekilde değerlendirilmesini kolaylaştırmak için uygun modelleme ve optimizasyon şeması içinde kullanılmalıdır. Geleneksel olarak, düşük mertebeden polinom modellerine dayanan yanıt yüzey yöntemi, verim gibi tek hedefli optimizasyon için kullanılır. Bu çalışmada, Kriging ve Pareto-front çok hedefli optimizasyonunu kullanan alternatif bir modelleme ve optimizasyon yaklaşımı, geleneksel şemaya kıyasla her iki prosedürün uygulanabilirliği ve verimliliği ile ilgili konulara dikkat çekerek, yeni bir lipaza uygulanmaktadır. Kriging temelli modelleme ve optimizasyon yönteminin, sınırlı ön deneysel verilerin kullanılmasında avantajlı olduğu gösterilmiştir.Biodiesel is a renewable and potentially sustainable alternative to petroleum-based diesel, especially in the transportation sector. Biodiesel can be produced by non-catalytic thermal methods, homogenous or heterogenous chemical conversions, and biocatalytic transformations using various types of feedstock such as crude, refined or waste oils, or animal fats. Commercial feasibility of biocatalytic biodiesel production from waste cooking oil critically depends on the availability of novel lipases, which catalyze the transesterification of triglycerides and esterification of free fatty acids in the feedstock into fatty acid alkyl esters, with the potential to be locally and economically produced. In this respect, screening, selection, and development of different lipases with varying properties from different sources is an essential task towards making lipase-catalyzed biodiesel production an attractive endeavor. Early evaluation of novel lipases employs time progress experiments under varying reaction temperature, alkyl receptor to substrate molar ratio, and enzyme amount. The preliminary data acquired from these early experiments need to be used within an appropriate modelling and optimization scheme to facilitate rapid and efficient evaluation of the novel lipase. Conventionally, response surface methodology based on low-order polynomial models is used for the optimization of a single objective like yield. In this work, an alternative modelling and optimization approach employing Kriging and Pareto-front multi-objective optimization is applied to a novel lipase, in comparison to the conventional scheme, highlighting the issues regarding the applicability and efficiency of both procedures. Kriging-based modelling and optimization methodology is shown to be advantageous in making use of limited preliminary experimental data
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
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