Volume 2 Issue 1
Expression of Protein Tyrosine Kinase c-Src by Means of Protein Tyrosine Phosphatase in Pichia pastoris
Pham Ngoc Tu, Lei Shi, Xiangshan Zhou*, Yuanxing Zhang*
Active non-receptor Src protein tyrosine kinases are usually expressed with very low yield due to protein toxicity associated with its kinase activity. In this study, Src was expressed by means of Protein Tyrosine Phosphatase 1B (PTP1B) to facilitate the production of active Src by neutralizing their apparent toxicity to cells in Pichia pastoris. Several recombinant Src-producing strains were constructed, and they displayed the catalytic activity of protein tyrosine phosphatase. The plasmid with c-Src fused with a his-tag and Green Fluorescent Protein (GFP) was transformed into P. pastoris with/without PTP1B, resulting in five recombinants with different expression levels.
Production and Functional Properties of Free and Immobilized Glucoamylases of Penicillium citrinum
Caio Cesar de Carvalho, Luciana Sobrani Ziotti, Marita Gimenez Pereira, Andrezza Furquim da Cruz, João Atílio Jorge, Maria de Lourdes Teixeira Moraes Polizeli*
Amylases are enzymes with important biotechnological applications that are produced by several microorganisms in the form of filamentous fungi. Penicillium citrinum was recently isolated from the decomposed materials of tlantic Forest, Brazil. It was identified by internal transcribed spacer (ITS) and beta-tubulin, and presented with excellent amylolytic levels. Thin layer chromatography showed that the amylase system was constituted by glucoamylase. This enzyme showed high activity at 60°C, pH 5.5, and an increment of 160% of the relative activity in the presence of 2 mM MgCl2.
Assessment of the Role of Extracellular DNA and Protozoan Grazing in Aerobic Granular Sludge Development
Sodhi N, Scott A Rice, Staffan Kjelleberg, Diane McDougald*
A scaled-down batch reactor system, modelled on traditional laboratory scale batch reactors, was developed for the preliminary assessment of the role of a number of factors on microbial aggregation. Long-term batch reactors were used to investigate the role of extracellular DNA in the re-granulation of crushed granular sludge, while short-term reactors were used to assess the impact of protozoan grazing on aggregation and microbial community structure. Extracellular DNA was observed as halos and honeycomb structures within granules and was found to be integral to granular architecture. Grazing by heterotrophic protists was shown to increase and maintain aggregate size as well as significantly affect the microbial community structure.
Engineered Production of Tryprostatins in E. coli through Reconstitution of a Partial ftm Biosynthetic Gene Cluster from Aspergillus sp.
Gopitkumar R Shah# Shane R. Wesener# and Yi-Qiang Cheng*
Tryprostatin A and B are indole alkaloid-based fungal products that inhibit mammalian cell cycle at the G2/M phase. They are biosynthetic intermediates of fumitremorgins produced by a complex pathway involving a nonribosomal peptide synthetase (FtmA), a prenyltransferase (FtmB), a cytochrome P450 hydroxylase (FtmC), an O-methyltransferase (FtmD), and several additional enzymes.
Synthesis of Selenium Nanoparticles by Geobacillus wiegelii strain GWE1 Isolated from a Drying Oven
Muñoz-Ibacache SA*, Correa-Llantén, DN*, Blamey, JM*
Microorganisms play an important role absorbing and accumulating metals from their environments. In some cases this process leads to the formation of well-defined metallic nanoscale particles. These biologically synthesized nanoparticles differ from the chemically produced in their physical properties and stability, opening additional technological opportunities for their use. In this study, the thermophilic bacterium Geobacillus wiegelii strain GWE1 was able to produce selenium nanoparticles. Cultures exposed to Na2SeO3 turned from colourless into an intense red colour. This is indicative of salt reduction confirming the presence of elemental selenium. The use of 5% polyvinylpyrrolidone (PVP) in the culture medium reduced the size of the nanoparticles from 250 nm to 120 nm (52% smaller).