A Novel L-Asparaginase from Hyperthermophilic Archaeon Thermococcus sibiricus: Heterologous Expression and Characterization for Biotechnology Application

L-asparaginase (L-ASNase) is a vital enzyme with a broad range of applications in medicine and food industry. Drawbacks of current commercial L-ASNases stimulate the search for better-producing sources of the enzyme, and extremophiles are especially attractive in this view. In this study, a novel L-asparaginase originating from the hyperthermophilic archaeon Thermococcus sibiricus (TsA) was expressed in Escherichia coli, purified and characterized. The enzyme is optimally active at 90 °C and pH 9.0 with a specific activity of 2164 U/mg towards L-asparagine. Kinetic parameters KM and Vmax for the enzyme are 2.8 mM and 1200 µM/min, respectively. TsA is stable in urea solutions 0–6 M and displays no significant changes of the activity in the presence of metal ions Ni2+, Cu2+, Mg2+, Zn2+ and Ca2+ and EDTA added in concentrations 1 and 10 mmol/L except for Fe3+. The enzyme retains 86% of its initial activity after 20 min incubation at 90 °C, which should be enough to reduce acrylamide formation in foods processed at elevated temperatures. TsA displays strong cytotoxic activity toward cancer cell lines K562, A549 and Sk-Br-3, while normal human fibroblasts WI-38 are almost unsensitive to it. The enzyme seems to be a promising candidate for further investigation and biotechnology application.

Characterization of a new esterase for enantioselective resolution of (R, S)-methyl mandelate

A new esterase gene (EST35) was cloned from Dactylosporangium sp. BB08 and expressed in E. coli BL21 (DE3). Optimum catalytic activity of EST35 was at 30 C and it could be activated at 0 °C. EST35 remained high activity in 20% (V/V) cyclohexane, hexane, heptane, methanol and DMSO. Interestingly the enzyme exhibits good enantioselectivity towards (R, S)-methyl mandelate leaving with an optical purity of 97% (R)-methyl mandelate and make EST35 a promising enzyme for biotechnology application.

Study of Siderurgy Slags for the Reuse of Iron Oxides for Biotechnology Application

The reuse of slag for the extraction of iron oxides, besides allowing the use of potentially polluting material, allows its strategic use in biotechnological applications. For this it is necessary a characterization of the slag as the proportion of iron oxides to study the feasibility of extraction and reuse. For this work siderurgy slag was collected in the steel mill slag yards, as a remnant of the transformation of pig iron into steel and study for identify the presence of magnetite in the samples. Results were discussed in the context of reuse possibility in biotechnological application, for example, in implants of the magnetic materials. The siderurgy slag studied presents iron oxides in a proportion that encourages future work of extraction for use in the composition of magnetic materials for biotechnological applications.