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Anoth Maharjan,Bassam Alkotaini,김범수 한국생물공학회 2018 Biotechnology and Bioprocess Engineering Vol.23 No.1
Bifunctional cellulase (glycoside hydrolase 5, GH5) from Bacillus sp. D04 having both endo- and exoglucanase activities was fused with two types of carbohydrate binding modules (CBMs). CBM3 from Bacillus sp. D04 and CBM9 from Thermotoga maritima Xyn10A were added to GH5 to hydrolyze microcrystalline cellulose (Avicel) as well as water-soluble cellulose (carboxymethyl cellulose, CMC). The optimum temperature of GH5 was 50oC, while it increased to 60oC for the fusion GH5-CBM3 and GH5-CBM9, indicating that addition of CBM increased the thermostability of the enzyme. Addition of CBM3 and CBM9 enhanced the GH5 affinity (KM), for which KM decreased from 104 to 33.9 ~ 35.1 mg/mL for CMC, and from 115 to 55.5 ~ 80.3 mg/mL for Avicel, respectively. The catalytic efficiency (kcat/KM) also increased from 4.80 to 5.36 ~ 6.46 (mL/mg)/sec for CMC, and from 1.77 to 2.40 ~ 4.45 (mL/mg)/sec for Avicel, respectively, by addition of CBM3 and CBM9.
Beom Soo Kim,Bassam Alkotaini,Hyunseok Koo 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.5
Polyhydroxyalkanoates (PHAs) are linear polyesters synthesized by microbial fermentation of various substrates. PHAs are accumulated in microbial cells in order to store carbon and energy for future use. We used acid-pretreated red alga (Gelidium amansii) as a cheap, abundant carbon source to produce PHA via batch and fed-batch cultivation of Bacillus megaterium KCTC 2194. After acid treatment of 10% (w/v) G. amansii, 25.5 g/L galactose, 3.6 g/L glucose, 6 g/L 5-HMF, and 1.05 g/L levulinic acid were formed. In batch culture at pH 7, the dry cell weight (DCW) and PHA content increased to 5.5 g/L and 51.4%, respectively. The cell concentration was enhanced by fed-batch cultivation using two feeding strategies: pH-stat and intermittent feeding. When the pH-stat feeding strategy was employed to add concentrated hydrolysate to the fermentor, DCW increased to 8.2 g/L, with 53.2% PHA content. When concentrated hydrolysate was fed using the intermittent feeding strategy, higher DCW (10.1 g/L) was obtained, along with a slight increase of PHA content to 54.5%. This study demonstrates that red algae could be used after simple acid treatment, to produce PHA without steps for enzymatic hydrolysis and inhibitor removal.
SALUNKE BIPINCHANDRA,김범수,Jia Shin,Shailesh S. Sawant,Bassam Alkotaini,이시춘 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.11
Silver nanoparticles (AgNPs) have promising potential in biomedicine, energy science, optics, and healthcare applications. We synthesized AgNPs using plant, leaf extract. UV-visible spectrophotometricstudy showed the characteristic peak for AgNPs at wavelength 430 nm. The optical density at 430 nm increased afteraddition of plant leaf extract, indicating increase in formation of nanoparticles. Comparative time course analyses forAgNP synthesis carried out at different reaction temperatures (20, 60, and 90 oC) revealed higher reaction rate forthan plant leaf extract, which showed highest AgNP synthesis rate in the previous report. Electronmicroscopy analyses confirmed the presence of well dispersed AgNPs, predominantly with spherical shapes. In trans-mission electron microscopy, the particle size decreased with increase in temperature. Electron dispersive X-ray spec-troscopy analyses indicated that Ag content increased with increase in reaction temperature. Fourier transform-infraredspectroscopy studies revealed capping of bioorganics from plant to the synthesized AgNPs. The antimicrobial activityof the synthesized AgNPs against increased with increase in reaction temperature. The observationsin this study will prove beneficial in approaching rapid synthesis of AgNPs and their antimicrobial application.
Salunke, Bipinchandra K.,Sawant, Shailesh S.,Kang, Tae Koo,Seo, Deok Yun,Cha, Youngjong,Moon, Sun A.,Alkotaini, Bassam,Sathiyamoorthi, Ezhaveni,Kim, Beom Soo Hindawi Limited 2015 Journal of nanomaterials Vol.2015 No.-
<P>Silver nanoparticles (AgNPs) as a result of their excellent optical and electronic properties are promising catalytic materials for various applications. In this study, we demonstrate a novel approach for enhanced degradation of cellulose using biosynthesized AgNPs in an enzyme catalyzed reaction of cellulose hydrolysis by cellulase. AgNPs were synthesized through reduction of silver nitrate by extracts of five medicinal plants (<I>Mentha arvensis</I>var.<I>piperascens, Buddleja officinalis</I>Maximowicz,<I>Epimedium koreanum</I>Nakai,<I>Artemisia messer-schmidtiana</I>Besser, and<I>Magnolia kobus</I>). An increase of around twofold in reducing sugar formation confirmed the catalytic activity of AgNPs as nanocatalyst. The present study suggests that immobilization of the enzyme onto the surface of the AgNPs can be useful strategy for enhanced degradation of cellulose, which can be utilized for diverse industrial applications.</P>