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Mutagenesis and selective breeding of a high producing

Tian WANG, Shiru JIA, Zhilei TAN, Yujie DAI, Shuai SONG, Guoliang WANG

《化学科学与工程前沿（英文）》 2012年第6卷第2期页码 179-183 doi: 10.1007/s11705-012-1273-6

摘要： -Poly- -lysine ( -PL) is an -lysine linear homopolymer, which is produced by bacteria belonging to the family and by ergot fungi. However, the production of -PL by the wild bacteria strain is very low, which limits its utilization. In most bacteria including the genus, -lysine is a precursor of -PL and is biosynthesized by the -aspartate pathway. Aspartokinase (Ask) is the first key enzyme in this pathway and is subject to complex regulation such as the feedback inhibition by the end product amino acids. In addition, phosphoenolpyruvate carboxykinase is feedback-regulated by -aspartate. To reduce these feedback inhibitions and to improve -PL productivity, resistant mutants were produced using sulfaguanidine (SG) + glycine+ -lysine+ -3-hydroxynorvaline (AHV) as selective markers. Using the interaction between -PL and the charged dye in the solid culture medium, hundreds of colonies were simultaneously screened in a quick and effective manner. Finally, one -PL-producing strain, L9, was selected. The productivity of this strain during flask fermentation was 0.77 g/L, which was 15% higher than that of the original strain. Moreover, its fermentation performance and genetic characteristics were very stable.

关键词： ?-poly-L-lysine plasma AHV Streptomyces diastatochromogenes fermentation

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Application of statistical design for the production of inulinase by

M. DILIPKUMAR, M. RAJASIMMAN, N. RAJAMOHAN

《化学科学与工程前沿（英文）》 2011年第5卷第4期页码 463-470 doi: 10.1007/s11705-011-1112-1

摘要： A Plackett-Burman design was employed for screening 18 nutrient components for the production of inulinase using sp. and pressmud as the substrate via solid-state fermentation (SSF). From the experiments, three nutrients viz. yeast extract, FeSO ·7H O, and NH NO were found to be the most significant components. Hence these three components were selected and optimized using Response Surface Methodology (RSM). The optimum conditions are: yeast extract 0.00274 g/gds, FeSO ·7H O 0.00011 g/gds and NH NO 0.00772 g/gds. The effect of the substrate concentration and initial moisture content were also studied. A substrate concentration of 12 g and an initial moisture content of 65% are optimum for the maximum production of inulinase (89 U/gds).

关键词： inulinase pressmud Response Surface Methodology (RSM) streptomyces sp

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Biosorption of mercury and lead by aqueous

Pratibha SANJENBAM, Kumar SAURAV, Krishnan KANNABIRAN

《化学科学与工程前沿（英文）》 2012年第6卷第2期页码 198-202 doi: 10.1007/s11705-012-1285-2

摘要： Toxic heavy metals are increasingly accumulating in the environment worldwide and are considered to be life threatening contaminants. The biosorption of mercury and lead by marine actinomycetes isolated from marine sediment collected from the Bay of Bengal coast of Puducherry, India, was evaluated. The maximum tolerance concentration (MTC) of sp. was determined by a well diffusion method and a broth dilution method. The effects of the initial metal ion concentration, the pH and the biomass dosage on the biosorption of mercury and lead ions were investigated. The MTC of the isolate to metals was 200 mg·L for mercury and 1800 mg·L for lead. At neutral pH, the isolate had a maximum biosorption of metal ions of 200 mg·L and 150 mg·L for mercury and lead respectively. Fourier transform infrared (FTIR) absorption spectra showed the chemical interactions between the functional groups in the biomass such as hydroxyl (-OH), amine (-NH ), carboxyl (-COOH) and the metal ions. The isolate was further characterized by molecular taxonomy and identified as a member of the genus Based on the phenotypic and phylogenetic analysis, the strain was classified as a new species of the genus and designated as VITSVK9 sp. (HM137310). A blast search of the 16S rDNA sequence of the strain showed the most similarity (95%) with sp. A515 Ydz-FQ (EU384279). Based on the results, it can be concluded that this marine could be used as a biosorbent for the removal of heavy metal ions from aqueous environments.

关键词： mercury lead biosorption maximum tolerance concentration Streptomyces VITSVK9 sp.

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VITHM1 mediated green synthesis of silver nanoparticles: Mechanism and biological applications

Mani Abirami, Krishnan Kannabiran

《化学科学与工程前沿（英文）》 2016年第10卷第4期页码 542-551 doi: 10.1007/s11705-016-1599-6

摘要： We present the microbial green synthesis of silver nanoparticles (NPs) by VITHM1 strain (MTCC No. 12465). The secondary metabolites in the cell free supernatant of this bacterium when incubated with 1 mmol/L AgNO , mediated the biological synthesis of AgNPs. The synthesized AgNPs were characterized by UV-visible spectrum, X-ray diffraction (XRD), atomic force microscope, scanning electron microscopy equipped with energy dispersive spectroscopy, transmission electron microscopy, FT-IR spectroscopy, dynamic light scattering and zeta potential. They were highly stable and, spherical in shape with the average size of 30?50 nm. The secondary metabolites involved in the formation of AgNPs were identified gas chromatography-mass spectrography. The 3D structure of the unit cell of the synthesized AgNPs was determined using XRD data base. The synthesized AgNPs exhibited significant antibacterial activity against tested bacterial pathogens, and did not show haemolysis on human red blood cells. This green synthesis could provide a new platform to explore and use AgNPs as antibacterial therapeutic agents.

关键词： Streptomyces ghanaensis VITHM1 nanoparticles 3D structure antibacterial activity