Ji-Liang Tang

Isolation and partial characterization of novel genes encoding acidic cellulases from metagenomes of buffalo rumens

Aims:  To clone and characterize genes encoding novel cellulases from metagenomes of buffalo rumens.

Identification of Cellulase Genes from the Metagenomes of Compost Soils and Functional Characterization of One Novel Endoglucanase

Metagenomics, a new research field developed over the past decade, aims to identify potential enzymes from nonculturable microbes. In this study, genes encoding three glycoside hydrolase family (GHF) 9 endoglucanases and one GHF 5 endoglucanase were cloned and identified from the metagenome of the compost soils. The shared identities between the predicted amino acid sequences of these genes and their closest homologues in the database were less than 70%. One GHF 9 endoglucanase, Umcel9B, was further characterized. The recombinant protein, Umcel9B, showed activity against carboxymethyl cellulose, indicating that Umcel9B is an endoactive enzyme. Enzymatic activity occurs optimally at a pH of 7.0 and a temperature of 25°C.

Novel Carbohydrate-Binding Module Identified in a Ruminal Metagenomic Endoglucanase

ABSTRACT Endoglucanase C5614-1 comprises a catalytic module (CM) and an X module (XM). The XM showed no significant homology with known carbohydrate-binding modules (CBMs). Recombinant full-length endoglucanase could bind Avicel, whereas the CM could not. The XM could bind various polysaccharides. The results demonstrated that the XM was a new CBM.

Involvement of OsNPR1/NH1 in rice basal resistance to blast fungus Magnaporthe oryzae

Rice blast disease, caused by the fungus Magnaporthe oryzae, is a major threat to worldwide rice production. Plant basal resistance is activated by virulent pathogens in susceptible host plants. OsNPR1/NH1, a rice homolog of NPR1 that is the key regulator of systemic acquired resistance in Arabidopsis thaliana, was shown to be involved in the resistance of rice to bacterial blight disease caused by Xanthomonas oryzae pv. oryzae and benzothiadiazole (BTH)-induced blast resistance. However, the role of OsNPR1/NH1 in rice basal resistance to blast fungus M. oryzae remains uncertain. In this study, the OsNPR1 gene was isolated and identified from rice cultivar Gui99. Transgenic Gui99 rice plants harbouring OsNPR1-RNAi were generated, and the OsNPR1-RNAi plants were significantly more susceptible to M. oryzae infection. Northern hybridization analysis showed that the expression of pathogenesis-related (PR) genes, such as PR-1a, PBZ1, CHI, GLU, and PAL, was significantly suppressed in the OsNPR1-RNAi plants. Consistently, overexpression of OsNPR1 in rice cultivars Gui99 and TP309 conferred significantly enhanced resistance to M. oryzae and increased expression of the above-mentioned PR genes. These results revealed that OsNPR1 is involved in rice basal resistance to the blast pathogen M. oryzae, thus providing new insights into the role of OsNPR1 in rice disease resistance.

Purification of Two Antimicrobial Substances Produced by Bacillus subtilis Strain B11 and Their Properties

Two antimicrobial substances produced by Bacillus subtilis strain B11 were purified by boiling, DEAE 52 anion exchange chromatography and aluminum oxide adsorption chromatography. These purified substances showed only one spot on silica gel thin layer chromatography (TLC). Antimicrobial assays showed that antimicrobial substances A and B inhibited the growth of plant pathogens such as Fusarium oxysporum Schl f.sp. niveum, Rhizoctonia solani, Ralstonia solanacearum and Xanthomonas oryzae pv. oryzae. In addition, antimicrobial substance B could also inhibit the growth of Magnaporthe grisea. These two antimicrobial substances were resistant to proteolytic enzymes and temperature as high as 121℃.