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We report a draft sequence for the genome of the domesticated silkworm (Bombyx mori), covering 90.9% of all known silkworm genes. Our estimated gene count is 18,510, which exceeds the 13,379 genes reported for Drosophila melanogaster. Comparative analyses to fruitfly, mosquito, spider, and butterfly reveal both similarities and differences in gene content., Silk fibers are derived from the cocoon of the silkworm Bombyx mori, which was domesticated over the past 5000 years from the wild progenitor Bombyx mandarina (1). Silkworms are second [...]

Plant surface is colonised with a vast community of non-pathogenic epiphytic microorganisms which play an important role in host defence. In the present study, we reported a fungus from mulberry leaf surface that showed an antagonistic effect against mulberry powdery mildew fungal pathogenPhyllactiniasp. This novel isolate is a yeast-like fungus that was identified asPseudozyma aphidisCNm2012 based on morphologic and phylogenetic analysis. According to our research,P. aphidisCNm2012 directly acted on the powdery mildew conidia via parasitism which caused conidial atrophy, collapse and eventually, cleavage and death. During the parasitic process, we found the isolate could gather around the conidia ofPhyllactiniasp. and form hyphae that grew on the conidial surface and utilise the conidia as a nutrient source. Field studies revealed thatP. aphidisCNm2012 could suppress the disease incidence of mulberry powdery mildew caused byPhyllactiniasp., and reduce the disease severity. To our knowledge, it is the first report ofP. aphidisdirectly against powdery mildew fungusPhyllactiniaspp. by parasitism. Our results indicated thatP. aphidisCNm2012 could be served as an environmentally friendly alternative of chemical pesticides to manage mulberry powdery mildew disease. [ABSTRACT FROM AUTHOR]

To investigate whether Bombyx mori Linnaeus (Lepidoptera: Bombycidae) intestinal microorganism play a role in the host defence system against viral pathogens, a lipase gene from the silkworm intestinal bacterium Bacillus pumilus SW41 was characterized, and antiviral activity of its protein against B. mori nucleopolyhedrovirus (BmNPV) was tested. The lipase gene has an open-reading frame of 648 bp, which encodes a 215-amino-acid enzyme with a 34-amino-acid signal peptide. The recombinant lipase (without signal peptide) was expressed and purified by using an Escherichia coli BL21 (DE3) expression system. The total enzyme activity of this recombinant lipase reached 277.40 U/mg at the optimum temperature of 25°C and optimum pH value of 8.0. The antiviral test showed that a relative high concentration of the recombinant lipase reduced BmNPV infectivity in vitro, which resulted in decreased viral DNA abundance and viral occlusion bodies. Besides, the preincubation method also suggested that the lipase probably directly acting on the budded virions. The results suggest that the lipase from intestinal bacterium B. pumilus SW41 is a potential antiviral factor for silkworm against BmNPV. [ABSTRACT FROM AUTHOR]

Objective: We screened bacterial strains that have strong antagonism against Beauveria bassiana, an important pathogen of silkworm industry, and detected the antagonistic activity of lipopeptide metabolites., Methods: We identified bacterium SWB16 by morphological observation, physiological and biochemical experiments, 16SrRNA, and gyrA gene sequence analysis, tested antagonistic activity of strain SWB16 against Beauveria bassiana by measuring the inhibition zone diameter using filter paper diffusion method (Kirby-Bauer method), obtained lipopeptide metabolites of the strain using methanol extraction and observed the antagonism of strain SWB16 lipopeptide extracts against the conidia and hyphae of Beauveria bassiana, detected main ingredients and genes of lipopeptide metabolites by high-performance liquid chromatography-mass spectrometry and PCR amplification., Results: SWB16 isolated from tissue of plant Dioscorea zingiberensis C. H. Wright belongs to Bacillus amyloliquefaciens and showed high antagonistic activity to Beauveria bassiana, and the lipopeptide extracts of isolate SWB16 exhibited significant inhibition to conidial germination and mycelial growth of Beauveria bassiana. The result of mass spectrometric detection indicated main component of the lipopeptide metabolites were fengcin and iturin, and genes fenB, ituA involved in the synthesis of them were amplified in the genome., Conclusion: Bacillus amyloliquefaciens strain SWB16 could produce lipopeptide antibiotics with strong antagonism to the entomopathogenic fungus Beauveria bassiana, and the results suggested that strain SWB16 has potential application value for controlling white muscardine of economic insects including silkworm.

Objective: We studied the antibiotic activity and selective cytotoxicity of beta-1,3-1,4-glucanase from endophytic Bacillus subtilis SWB8., Methods: Based on gel permeation chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and liquid chromatography-tandem mass spectrometry methods, protein fragments of beta-1,3-1,4-glucanase from endophytic Bacillus subtilis strain SWB8 were purified and identified. Then, beta-1,3-1,4-glucanase was used to evaluate the antimicrobial activity against Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, Escherichia coli, Salmonella typhi, Salmonella paratyphi A, Shigella dysenteriae, Candida albicans and Cryptococcus neoformans and cytotoxicity against human pulmonary adenocarcinoma cells (A549) and human bone marrow mesenchymal stem cells (MSCs) by using the disc diffusion, methyl thiazolyl tetrazolium and flow cytometry methods, respectively., Results: Bacterial beta-1,3-1,4-glucanase showed broad antimicrobial spectrum against all nine bacterial and fungal strains. Furthermore, beta-1,3-1,4-glucanase possessed significant anticancer activity against A549 cells that the IC50 and IC90 values were 11.5 and 20.1 microg/mL, respectively. The percentage of apoptotic A549 cells treated with different concentrations of beta-1,3-1,4-glucanase was significantly increased from 4.43% of the control to 43.1% of 19.2 microg/mL glucanase in a dose dependent manner. In contrast, these changes could not be observed in human bone marrow mesenchymal stem cells., Conclusion: Beta-1,3-1,4-glucanase could be a potential source of desirable antimicrobial agent, or anticancer compounds with higher efficiency and lower toxicity.

Objective: In order to understand the role of the entomopathogenic fungal chitinase in invasion and pathogenic process, we cloned and expressed a chitinase gene from Nomuraea rileyi CQ strain, and detected chitinase activity in recombinant Pichia pastori fermentation supernatant., Methods: Specific primers were used to amplify the complete sequence of chitinase gene and open reading frame (ORF) from genomic DNA of N. rileyi Cq Strain extracted by CTAB. The fragment of ORF was linked with vector plasmid pPIC9K to construct the pPIC9K-chit1 expressing vector and transferred into Pichia pastori. The recombinant yeast P. pastori was screened by 1.5 mg/L G418 and PCR check. Activity of chitinase in recombinant P. pastori fermentation liquid was verified by transparent zone test and OD540 determination, and the molecular weight of chitinase was analyzed by SDS-PAGE., Results: The complete sequence length of chitinase gene of N. rileyi CQ strain is 2756 bp (GenBank accession number EU795711) that contains a 1827bp of ORF chit1, a 76 bp uncoding region at the 5' end, a 240 bp uncoding region at the 3' end, and 3 introns. The ORF chit1 encoding 424 amino acids of chitinase precursor, and the theoretical restriction site of single peptide is between Gly (20) and Leu (21). Activity of chitinase expressed by recombinant P. pastoris increased with fermentation time, and reached the peak of 482.5 U/100 microL at 72 h. Hydrolysis test of chitin showed clear transparent zone at the 1% colloidal chitin plate. SDS-PAGE analysis suggested that the molecular weight of chitinase was 41.0 kDa., Conclusion: We cloned the chitinase gene Chit1 from N. rileyi CQ strain and expressed in recombinant P. pastori successfully to study the infection and lethal mechanism of pathogenic fungi to insects.

Objective: Vairimorpha ceraces is a new microsporidium that isolated from the insect of Lepidoptera, Cerace Stipatana (Walker). We used 16S rDNA sequence to explore genetic status of Vairimorpha ceraces., Methods: SSU rDNA (small subunit ribosomal RNA) of Vairimorpha ceraces was cloned and sequenced for constructing phylogenetic tree through Neighbor-joining., Results: The core sequence of SSU rRNA of Vairimorpha ceraces with a length of 1228 nucleotides (GenBank EU267796) was successfully cloned and sequenced. Phylogenetic analysis showed that Vairimorpha ceraces was closer to the species of Vairimorpha sp. Germany (GenBank AF124331) and Vairimorpha imperfecta (GenBank AJ131645), both isolated from Plutella xylostella. The three species of genera Vairimorpha included Vairimorpha ceraces formed a clade with the Nosema spp. which from Lepidoptera host in phylogenetic tree. Conversely, other three Vairimorpha spp. from Lepidoptera (Vairimorpha necatrix, Vairimorpha sp. NISM12 and Vairimorpha lymantriae) were mixed with Nosema spp. from non-lepidopteran host in the other clade., Conclusion: Combined with the biological characters, Vairimorpha ceraces was a member of genera Vairimorpha, Family Nosematidae.