Diversity and function of microbial communities in the sand sheath of Agropyron cristatum by metagenomic analysis.

The roots of most gramineous plants are surrounded by a variety of microorganisms; however, few studies have focused on the rhizosheath of psammophytes. Therefore, in this study, we used Illumina HiSeq high-throughput sequencing technology to analyse the composition and functional diversity of microbial communities in the rhizosheath of sand-grown Agropyron cristatum (L.) Gaertn. We found that the number of species and functions of microbial communities gradually decreased from the rhizosheath to the bulk soil. Thus, the microbial composition of the rhizosheath was richer and more diverse, and the abundance of bacteria, including Sphingosinicella, Rhizorhabdus, Friedmanniella, Geodermatophilus, Blastococcus, and Oscillatoria, was higher, and the abundance of fungi, such as Mycothermus, was higher. The abundance of CO2 fixation-related genes (acsA, Pcc, and cbbL) in the carbon cycle; NO3-, NO2-, NH2OH, and N2 transformation genes (nrtP, nirS, hao, and nifK) in the nitrogen cycle; soxB/A/C, Sat, and dsrB genes in the sulphur cycle; and 1-phosphate mannitol dehydrogenase (MtlD) gene and polyketide synthase gene (pks) were higher in the rhizosheath than in the bulk soil, as well as genes related to phosphorus uptake in the phosphorus cycle. Our findings showed that the rhizosheath may host the predominant microbial species related to the formation of a rhizosheath.

Gene insertion in Saccharomyces cerevisiae using the CRISPR/Cas9 system.

The aim of this work was to rapidly and efficiently insert target DNA sequences into predetermined genomic sites in Saccharomyces cerevisiae. In this study, we designed two technical routes for gene insertion in the S. cerevisiae genome based on the CRISPR/Cas9 system, and a CRISPR array was inserted into the Amp site and the crRNA site of the pCRCT plasmid, respectively. The CRISPR array consists of a 100 bp donor sequence, the target gene and guide sequence. A 100 bp donor sequence was designed to have two 50 bp homology arms flanking the Cas9 cutting site and incorporate 8 bp or 1000 bp deletions including the PAM sequence, where the target gene was also inserted. The results showed that using only one pCRCTG plasmid and a 100 bp dsDNA mutagenizing homologous recombination donor, we can successfully insert a 2.9 kb gene fragment at the target site of the S. cerevisiae genome. However, inserting the CRISPR array into the crRNA site has a higher recombination efficiency than inserting into the Amp site. This recombination strategy represents a powerful tool for creating yeast strains with target gene inserts.

Study on acrylate peelable nuclear detergent for film formation at low temperature.

The human handling of radioactive contamination on the surface of nuclear facilities has become an important issue in the development of nuclear industry. In order to solve the poor film-forming of nuclear detergent in low temperature, a new type low temperature film-forming peelable nuclear decontaminant was proposed. The acrylate copolymers were developed by solution polymerization of acrylic monomers in the mass ratio of BA (butyl acrylate): MMA (methyl methacrylate): AA (acrylic acid): EA (ethyl acetate) is equal to 50:45:5:100 considering different proportioning methods and reaction temperature. Then the orthogonal test was carried out to study the effects of crosslinker, plasticizer, thickener, release agent on the decontamination performance based on the orthogonal test method, and the optimal peelable formula of peelable nuclear detergent was obtained. Next the infrared properties, glass transition temperature, molecular weight of polymer and decontamination efficiency of peelable nuclear decontaminant were studied by experiments. The results show that the proposed low-temperature film-forming peelable radioactive decontamination agent can form film on concrete, sand, terrazzo, stainless steel and other surfaces, and is easy to peel off. The decontamination rate of this material is more than 82%.