BackgroundManganese peroxidase (MnP) from Irpex lacteus F17 has been shown to have a strong ability to degrade recalcitrant aromatic pollutants. In this study, a recombinant MnP from I. lacteus F17 was expressed in Escherichia coli Rosetta (DE3) in the form of inclusion bodies, which were refolded to achieve an active enzyme. Further, we optimized the in vitro refolding conditions to increase the recovery yield of the recombinant protein production. Additionally, we attempted to express recombinant MnP in soluble form in E. coli, and compared its activity with that of refolded MnP.ResultsRefolded MnP was obtained by optimizing the in vitro refolding conditions, and soluble MnP was produced in the presence of four additives, TritonX-100, Tween-80, ethanol, and glycerol, through incubation at 16 °C. Hemin and Ca2+ supplementation was crucial for the activity of the recombinant protein. Compared with refolded MnP, soluble MnP showed low catalytic efficiencies for Mn2+ and H2O2 substrates, but the two enzymes had an identical, broad range substrate specificity, and the ability to decolorize azo dyes. Furthermore, their enzymatic spectral characteristics were analysed by circular dichroism (CD), electronic absorption spectrum (UV-VIS), fluorescence and Raman spectra, indicating the differences in protein conformation between soluble and refolded MnP. Subsequently, size exclusion chromatography (SEC) and dynamic light scattering (DLS) analyses demonstrated that refolded MnP was a good monomer in solution, while soluble MnP predominantly existed in the oligomeric status.ConclusionsOur results showed that two forms of recombinant MnP could be expressed in E. coli by varying the culture conditions during protein expression.Electronic supplementary materialThe online version of this article (doi:10.1186/s12896-016-0317-2) contains supplementary material, which is available to authorized users.
Abstract65 strains of endophytic actinomycetes were isolated from Achyranthes bidentata, Paeonia lactiflora, Radix Platycodi and Artemisiae argyi. Active strains of inhibiting penicillin-resistant staphylococcus aureus were screened from these strains and some were identified preliminarily. The results showed that 12 strains among these 65 strains of endophytic actinomycetes were able to suppress penicillin-resistant staphylococcus aureus. Through the observation on morphology of mycelium and phylogenetic analysis of 16S rDNA, a strain belongs to the genus Glycomyces and most other as the genus Streptomyces.
An endophytic actinomycete strain, IXS4 T and the closely related type strains were well below 70 %. The strain also showed a number of physiological and biochemical characteristics that were distinct from the closely related species. The strain contained MK-10(H 2 ) and MK-11(H 0 ) as the detected menaquinones. The peptidoglycan was mainly meso-diaminopimelic acid and the whole-cell sugars contained galactose, glucose, mannose, xylose and ribose. The major cellular fatty acids were iso-C 14 : 0 , iso-C 15 : 0 , iso-C 16 : 0 , anteiso-C 15 : 0 and anteiso-C 17 : 0 . Based on the genetic and phenotypic properties, it is proposed that strain IXS4 T represents a novel species of the genus Glycomyces, with the name http://dx.
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