Preparation and characterization of high-ash coal slime-based soil amendment as well as investigations of its adsorption performance and mechanisms towards heavy metals in soil.

In this study, high-ash coal slime-based mineral soil amendment (MSA) was prepared via the hydrothermal method using high-ash coal slime as raw material, supplemented with activator calcium oxide and additive KOH solution. After hydrothermal treatment at 230 °C for 5 h, the original crystalline phase (quartz and kaolinite) of the high-ash slime was completely transformed into hydrotalcite zeolite, tobermorite, and silicate of potassium aluminosilicate, which has the largest specific surface area. The adsorption of Pb2+ and Cd2+ was adherent to the kinetic equation of secondary adsorption and Freundlich models, and the removal of Pb2+ and Cd2+ reached up to 362.58 mg g-1 and 64.67 mg g-1. The successive releases of SiO2 and CaO from MSA conformed to the Elovich equation, whereas the releases of SiO2 in Cd-containing environments and CaO in Pb- and Cd-containing environments more closely conformed to the power function; the releases of K2O all conformed to the first-order kinetic equation. The presence of Pb2+ and Cd2+ in the environment promotes the release of potassium and calcium elements with MSA's ion-exchange ability, and attenuates the release of silicon elements. Combining Pb2+ and Cd2+ with silicon resulted in the intolerant precipitation of 3PbO·2SiO2 and Cd2SiO4. The mineral precipitation mechanism is the most important mechanism of MSA in immobilizing heavy metals, accounting for 72.7%-80.5% of the total adsorption. Further contaminated soil immobilization experiments also showed that the application of MSA significantly reduced the bioavailability of soil heavy metals. When the MSA addition amount was 1.6%, the residual state increased by 63.58%. In conclusion, preparing MSA may effectively utilize coal-based solid waste with high added value.

Cloning a cuticle-degrading serine protease gene with biologic control function from Beauveria brongniartii and its expression in Escherichia coli.

Beauveria brongniartii extracellular subtilisin-like serine protease (Pr1) is one of the most virulent factors by virtue of its activity against insect cuticles. The Pr1 cDNA was cloned using the switching mechanism at the 5' end of the RNA transcript and rapid amplification of cDNA ends. The 1732-bp fragment of genomic DNA containing the predicted open-reading frame of the Pr1 gene was cloned by polymerase chain reaction and sequenced. The Pr1 cDNA is 1550 bp and contains an 1140-bp ORF. The deduced amino-acid sequence of the protein shows identity to that of proteinase K from Tritirachium album (62%), Pr1 from Metarhizium nisopliae (67%), and Pr1 from B. bassiana (76%). The Pr1 protein with an N-terminal fusion to the six-histidine tag was expressed in Escherichia coli as inclusion bodies with the expression vector pBV220. Sodium dodecylsulsulfate-polyacrylamide gel electrophoresis clearly revealed expressed product. The Pr1 protein was purified and refolded and had proteolytic activity of 0.288 U mg(-1).