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  • Articles  (1,095)
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  • Articles  (1,095)
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  • 11
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    Transformation of cellobiose during the interaction of cellobiose dehydrogenase and β-glucosidase of Cerrena unicolor (2018)
    Wiley-Blackwell
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    Publication Date: 2018-02-09
    Description: This work investigated the regulatory role of the interaction between cellobiose dehydrogenase (CDH) and β-glucosidase (β-GLU) in the conversion of cellobiose into cellobionolactone or glucose in vitro . To study the regulation, the two enzymes were isolated from the culture medium of the fungus Cerrena unicolor grown on a medium with microcrystalline cellulose. The enzymes were obtained in an electrophoretically homogeneous state. Their properties were studied. Both enzymes had acidic pH optima and were more stable in the acidic pH range. CDH was moderately thermostable, while β-GLU had a low thermostability. Both enzymes efficiently catalyzed the transformation of cellobiose. A mixture of CDH and β-GLU transformed cellobiose to glucose or cellobionolactone in the presence of various concentrations of laccase and hydroquinone. Formation of glucose and cellobionolactone in vitro during the competition between CDH and β-GLU for cellobiose depended on the availability of quinones, formed as a result of the interaction of laccase and hydroquinone, for CDH. At low laccase and hydroquinone concentrations, the formation of glucose was found to predominate over that of cellobionolactone. The possible physiological role of the enzymes’ interaction is discussed.
    Print ISSN: 0233-111X
    Electronic ISSN: 1521-4028
    Topics: Biology
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  • 12
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    Cloning, expression, and characterization of thermal-stable and pH-stable agarase from mangrove sediments (2018)
    Wiley-Blackwell
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    Publication Date: 2018-02-08
    Description: AgaM1, a β-agarase belonging to glycoside hydrolases family 16 (GH16), was cloned from the environmental DNA of mangrove sediments. The gene agaM1 is 2136 bp in length and encodes a protein of 712 amino acids. The properties of recombinant AgaM1 (rAgaM1) were studied using prokaryotic expression. The optimum temperature and pH were 50 °C and 7.0, respectively, and rAgaM1 exhibited a high adaptability to wide ranges of temperature and pH. A relatively high activity was retained at from 30 to 60 °C and from pH 6.0 to 9.0. Thermal stability was showed more than 70% relative activity after pre-incubation at 40 °C for 60 h. Outstanding pH stability were observed for rAgaM1 from pH 5.0 to 10.0 after pre-incubation for 60 h. Thin-layer chromatography revealed neoagarotetraose (NA4) and neoagarohexaose (NA6) were the end-products of rAgaM1-degraded agarose. Besides, rAgaM1 were found with a K m of 1.82 mg ml −1 and a V m of 357.14 U mg −1 for agarose. The K m was smaller than those of most agarases reported previously. This discrepancy revealed the high affinity of rAgaM1 to agarose. Overall, the results indicated the potential of rAgaM1 in future industrial application.
    Print ISSN: 0233-111X
    Electronic ISSN: 1521-4028
    Topics: Biology
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  • 13
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    Green synthesized silver nanoparticles demonstrating enhanced in vitro and in vivo antibiofilm activity against Candida spp. (2018)
    Wiley-Blackwell
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    Publication Date: 2018-02-08
    Description: Candida species are opportunistic fungal pathogens, which are known for their biofilm associated infections on implanted medical devices in clinical settings. Broad spectrum usage of azole groups and other antifungal agents leads to the occurrence of drug resistance among Candida species. Most of the antifungal agents have failed to treat the biofilm mediated Candida infections. In the present study, silver nanoparticles (AgNPs) were synthesized using Dodonaea viscosa and Hyptis suoveolens methanolic leaf extracts and characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy and Scanning electron microscopy, Dynamic light scattering, and Zeta potential analysis. The main goal of this study was to assess the AgNPs for their antibiofilm efficacy against Candida spp. through microscopic analysis and in vitro virulence assays. The results revealed that AgNPs strongly inhibited more than 80% biofilm formed by Candida spp. Furthermore, the AgNPs also reduced the yeast-to-hyphal transition, exopolysaccharide biosynthesis, secreted aspartyl proteinase production which are the major virulence factors of Candida species. This study reveals that biosynthesized AgNPs can be considered for the treatment of biofilm related Candida infections.
    Print ISSN: 0233-111X
    Electronic ISSN: 1521-4028
    Topics: Biology
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  • 14
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    Expression and characterization of the processive exo-β-1,4-cellobiohydrolase SCO6546 from Streptomyces coelicolor A(3) (2018)
    Wiley-Blackwell
    Details
    Publication Date: 2018-02-06
    Description: The sco6546 gene of Streptomyces coelicolor A3(2) was annotated as a putative glycosyl hydrolase belonging to family 48. It is predicted to encode a 973-amino acid polypeptide (103.4 kDa) with a 39-amino acid secretion signal. Here, the SCO6546 protein was overexpressed in Streptomyces lividans TK24, and the purified protein showed the expected molecular weight of the mature secreted form (934 aa, 99.4 kDa) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. SCO6546 showed high activity toward Avicel and carboxymethyl cellulose, but low activity toward filter paper and β-glucan. SCO6546 showed maximum cellulase activity toward Avicel at pH 5.0 and 50 °C, which is similar to the conditions for maximum activity toward cellotetraose and cellopentaose substrates. The kinetic parameters k cat and K M , for cellotetraose at pH 5.0 and 50 °C were 13.3 s −1 and 2.7 mM, respectively. Thin layer chromatography (TLC) of the Avicel hydrolyzed products generated by SCO6546 showed cellobiose only, which was confirmed by mass spectral analysis. TLC analysis of the cello-oligosaccharide and chromogenic substrate hydrolysates generated by SCO6546 revealed that it can hydrolyze cellodextrins mainly from the non-reducing end into cellobiose. These data clearly demonstrated that SCO6546 is an exo-β-1,4-cellobiohydrolase (EC 3.2.1.91), acting on nonreducing end of cellulose.
    Print ISSN: 0233-111X
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    Topics: Biology
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  • 15
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    Issue Information: Journal of Basic Microbiology. 2/2018 (2018)
    Wiley-Blackwell
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    Publication Date: 2018-02-03
    Print ISSN: 0233-111X
    Electronic ISSN: 1521-4028
    Topics: Biology
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  • 16
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    Taxonomy characterization and plumbum bioremediation of novel fungi (2018)
    Wiley-Blackwell
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    Publication Date: 2018-02-03
    Description: The objective of this study was to investigate the screening, taxonomy characterization, Pb biosorption, and application of the high Pb-resistant fungus F1 separated from the heavy metal contaminated soil. Fungus F1 was screened through metal concentration gradient ranging from 25 to 4000 mg L −1 . The internal transcribed spacers (ITS) of the strain was analyzed by molecular biotechnology. The adsorption conditions were also evaluated. The precipitation of fungus F1 was analyzed by Scanning Electron Microscopy (SEM), Fourier transformer infrared spectroscopy (FTIR) and energy dispersive X-ray (EDX) techniques. The Pb speciation was determined by BCR three-step sequential extraction. The highest concentration of fungus F1 resistance to Pb 2+ was 3500 mg L −1 . The fungus was identified as Trichoderma asperellum . The optimum condition for the Pb 2+ removal rate was discovered as follows: MTL: 3500 mg L −1 ; pH: 7; Pb2+ concentration: 800 mg L −1 ; temperature was 30 °C; initial biosorbent dosage: 6% (v/v). The surface chemical functional groups of fungus F1 were amino, hydroxyl, and carbonyl groups, which may be involved in the biosorption of Pb. Application test showed that the exchangeable, acid-and water soluble Pb were reduced, and the sulfide, organic combination state, and residual Pb were increased. With the preferable absorption capacity, fungus F1 was considered to have good prospects of bioremediation.
    Print ISSN: 0233-111X
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    Topics: Biology
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  • 17
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    Cover: Journal of Basic Microbiology. 2/2018 (2018)
    Wiley-Blackwell
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    Publication Date: 2018-02-03
    Description: Cover illustration: Mixed filaments of G-1 and SF mutant of Arthrospira platensis (straight bundles) showing segregation of straight filament of SF mutant from the G-1 mutant (circular filaments). (Photo: P. K. Singh, Department of Botany, Banaras Hindu University, Varanasi, India)
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    Topics: Biology
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  • 18
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    Development of an efficient host-vector system of Ruminiclostridium josui (2018)
    Wiley-Blackwell
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    Publication Date: 2018-02-02
    Description: Although Ruminiclostridium josui (formerly Clostridium josui ), a strictly anaerobic mesophilic cellulolytic bacterium, is a promising candidate for biomass utilization via consolidated bioprocessing, its host-vector system has not yet been established. The existence of a restriction and modification system is a significant barrier to the transformation of R. josui . Here, we partially purified restriction endonuclease Rjo I from R. josui cell extract using column chromatography. Further characterization showed that Rjo I is an isoschizomer of Dpn I, recognizing the sequence 5′-G met ATC-3′, where the A nucleotide is Dam-methylated. Rjo I cleaved the recognition sequence between the A and T nucleotides, producing blunt ends. We then successfully introduced plasmids prepared from Escherichia coli C2925 ( dam − / dcm − ) into R. josui by electroporation. The highest transformation efficiency of 6.6 × 10 3 transformants/μg of DNA was obtained using a square-wave pulse (750 V, 1 ms). When the R. josui cel48A gene, devoid of the dockerin-encoding region, cloned into newly developed plasmid pKKM801 was introduced into R. josui , a truncated form of RjCel48A, RjCel48AΔdoc, was detected in the culture supernatant but not in the intracellular fraction. This is the first report on the establishment of fundamental technology for molecular breeding of R. josui .
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    Topics: Biology
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  • 19
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    Mercury tolerance and biosorption in bacteria isolated from Ny-Ålesund, Svalbard, Arctic (2018)
    Wiley-Blackwell
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    Publication Date: 2018-02-01
    Description: Mercury tolerant bacteria Pseudarthrobacter oxydans strain MM20 and Pseudomonas frederiksbergensis strain SS18 were isolated from the tundra ecosystem of Ny-Ålesund, Svalbard, where commercial exploitation of the coal existed till 1960s. Minimum inhibitory concentration (MIC), mercury removal, mercury biosorption, and antibiotic resistance of these strains were analyzed. P. frederiksbergensis strain SS18 showed high tolerance (2.0 ppm) to mercury than P. oxydans strain MM20 (1.5 ppm). Mercury removal and biosorption studies were carried out in liquid media containing 1.0 ppm mercury. More than 90% of mercury was removed from the culture media by the selected strains. The mercury biosorption assay revealed that a part of mercury was accumulated in cell pellets and was 22 and 25% respectively for P. oxydans strain MM20 and P. frederiksbergensis strain SS18. Fourier transform infrared study revealed that alkyl halide, alkynes, alcoholic, aliphatic and aromatic amines, alkanes, nitro compound, primary amines, carboxylic acid, alkenes, and amide groups play a major role in the development of tolerance towards mercury. Out of eleven antibiotics tested, P. oxydans strain MM20 was found to be resistant to lincomycin and novobiocin while P. frederiksbergensis strain SS18 was found to be resistant to seven antibiotics. Our study demonstrates that under experimental conditions, bacterial isolates undergo detailed structural and functional changes to tolerate as well as immobilize toxic elements like mercury.
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  • 20
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    Catechol 2,3-dioxygenase from a new phenolic compound degrader Thauera sp. K11: purification and biochemical characterization (2018)
    Wiley-Blackwell
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    Publication Date: 2018-01-31
    Description: Catechol 2,3-dioxygenase (C23O) from a new phenolic compound degrader Thauera sp. K11 was purified and characterized. The native form of the enzyme was determined as a homotetramer with a molecular weight of 140 kDa, and its isoelectric point was close to 6.4. One iron per enzyme subunit was detected using atom absorption spectroscopy, and the effective size of C23O in its dilute solution (0.2 g L −1 , pH 8.0) was 14.5 nm. The optimal pH and temperature were 8.4 and 45 °C, respectively. The addition of Mg 2+ , Cu 2+ , Fe 2+ , and Mn 2+ could improve the enzyme activity, while Ag + was found to be a strong inhibitor. C23O was stable in alkali conditions (pH 7.6–11.0) and thermostable below 50 °C. The final purified C23O had a sheet content of 53%, consistent with the theoretical value. This showed that the purified catechol 2,3-dioxygenase folded with a reasonable secondary structure.
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    Topics: Biology
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