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Phage display technology is a unique gene recombination expression technology, and it is also a simple and effective screening tool. Through panning, a protein or peptide with high affinity and selectivity to the target is obtained. Antibody phage display has become the first and most widely used in vitro screening technology. Phage display derivatives play an important role in the diagnosis and treatment of diseases. This article reviews the phage display system of phage display technology, the size and classification of antibody libraries and their applications, and discusses the application prospects and challenges of phage display technology. This thesis lays the foundation for the theoretical and experimental research of bacteriophages.

In order to understand the variation of FPV strains in the Jinan area, Shandong Province, China, the VP2 gene of 6 FPV strains was sequenced, and the analysis of the genetic relationship, evolution and main functional site variation was carried out. It was found that FPV-XY2, FPV-XY3 and FPV-XY6 were the same strain with 100% homology, and also close to FPV-XY1, and the homology between FPV-XY4 and FPV-XY5 was close. The homology between the reference strain and the test strain was over 99.3%. According to the evolutionary analysis, the genetic relationship among FPV-XY1, FPV-XY2, FPV-XY3, FPV-XY6 was close, and the genetic relationship between FPV-XY4 and FPV-XY5 was close, and the result was similar to the homologous result. Compared with the VP2 amino acid sequence of the standard strain FPV-CU4, the VP2 protein of all the test strains changed from I to t on the 101st Amino acid, this may be the cause of immune failure in these 6 cases; the change of a to s in the 91st amino acid position of FPV-XY1, FPV-XY2, FPV-XY3, FPV-XY6 may be the cause of enhanced virulence of FPV. This study provides a reference for exploring the epidemic law of FP in the Jinan area, the standard of FP treatment plan and the research and development of FPV subunit vaccine.

Electrolytic manganese residue (EMR) is a type of industrial solid waste with a high silicon content. The silicon in EMR can be used as an essential nutrient for plant growth, but most of the silicon is found in silicate minerals with very low water solubility, that is, it is inactive silicon and cannot be absorbed and used by plants directly. Thus, developing a highly effective and environmentally friendly process for the activation of silicon in EMR is important both for reusing solid waste and environmental sustainability. The aim of this study was to investigate the desilication of EMR using cultures of Paenibacillus mucilaginosus (PM) and Bacillus circulans (BC). The results showed that the two types of silicate bacteria and a mixed strain of them were all able to extract silicon from EMR with a high efficiency, but the desilication performance of the mixed PM and BC was the best. Fourier transform infrared spectroscopy indicated that silicate bacteria can induce a suitable micro-environment near the EMR particles and release Si into the solution through their metabolism. X-ray diffraction analysis confirmed that layered crystal minerals, such as muscovite and diopside, were more likely to be destroyed by the bacterial action than quartz, which has a frame structure. Scanning electron microscopy-energy dispersive spectrometry proved that the silicate structures were destroyed and that Si in the residue was decreased, indicating the dissolution of silicon under the action of these microorganisms. This study suggests that bioleaching may be a promising method for the activation of silicon in EMR.