The bactericidal spectrum and virucidal effects of silver nanoparticles against the pathogens in sericulture

Silver nanoparticles have mainly been studied for their antimicrobial potential against bacteria, but have also proven to be active against several types of viruses, even against pebrine as well. Methods: Petri dishes and transmission electronic microscope were applied to observe silver nanoparticles against bacteria strains and nuclear polyhedral viruses (NPV) and cytoplasmic polyhedral viruses (CPV). For biological test, 108 CFU/mL NPV with strong pathogenicity, and the NPV samples treated with 1:100 ratio of “Sumerian Silver” for 8 hrs were sprayed on the mulberry leaves, respectively, for silkworm rearing. Conclusion: Silver nanoparticle solution showed a strong bactericidal effect against both G+ and G﹣bacterial pathogenic strains from Bombyx mori and mulberry. Under transmission electronic microscope (TEM), Bacillus sp. Samples showed light particles in the cells when treated with silver nanoparticles, in contrast, untreated samples showed homogeneity contents. Further, NPV particles showed no significant differences between treated and untreated samples, but CPV showed strong effects that almost all CPV were collapsed. For biological test, “Sumerian Silver” treated NPV showed no diseased silkworm but nearly all silkworms were dead with no treatment. It seems like that silver nanoparticles were proved to be more effective against CPV than that of NPV. The significant differences between two antivirus or virucidal mechanism should be greatly aroused the scientific interest.

Secretive Expression of Insect Antifungal Peptide-Encoded Genes in Pichia pastoris and Activity Assay of the Products

The antifungal peptides, drosomycin (Drs) and its isoform drosomycin-like C (Drs-lC) from Drosophila melanogaster and Thanatin from Podisus maculiventris, have potent activity with broad spectrum against filamentous fungi. Secretive expression of these genes in yeasts makes it possible to utilize the supernatants of yeast culture as protective reagents on fruit, vegetable, food and other agricultural products. So the study of effective secretion by yeast expression system is of great importance. Three genes, Drs, Drs-lC, and Thanatin, were cloned into pPICZαA and the recombinant vectors, pPICZαA-Drs, pPICZαA-Drs-lC, and pPICZαA-Thanatin were transformed into Pichia pastoris by the electric transfer method. The recombinant P. pastoris, which was screened by phenotype selection and PCR amplification, was induced to express antifungal peptide by methanol. The expressive products of the three recombinants showed antifungal activity against 5 out of 6 test fungi strains, and the products of Thanatin also had strong activity against the tested bacteria. The three antifungal peptide genes, Drs, Drs-lC, and Thanatin, were constructed into yeast P. pastoris. The expressed peptides were successfully secreted into the culture medium and exhibited potent activities against the test strains.

Inducing and isolation of antibacterial peptides from oriental fruit fly, Bactrocera dorsalis Hendel

从一只使免疫的 dipteran 昆虫的一抗菌剂活动部分， Bactrocera 背面由 prepurification，离子交换层析，胶化过滤层析和反向阶段的高效液体层析(HPLC ) 是，被孤立并且净化。最后的净化的部分在聪明的系统 HPLC 上被检查并且被认为是纯部分。Theresults 物理并且生物检验表明这部分是热对克积极的细菌的生长的稳定、显示出的强壮的活动。它拥有 antibicrobial 肽性质并且值得进一步的调查。