Search

A powerful strategy for long-term and diffusional-resistance-minimized whole-cell biocatalysis in biphasic systems is reported where individually encapsulated bacteria are employed as robust and recyclable Pickering interfacial biocatalysts. By individually immobilizing bacterial cells and optimizing the hydrophobic/hydrophilic balance of the encapsulating magnetic mineral shells, the encased bacteria became interfacially active and locate at the Pickering emulsion interfaces, leading to dramatically enhanced bioconversion performances by minimizing internal and external diffusional resistances. Moreover, in situ product separation and biocatalyst recovery was readily achieved using a remote magnetic field. Importantly, the mineral shell effectively protected the entire cell from long-term organic-solvent stress, as shown by the reusability of the biocatalysts for up to 30 cycles, while retaining high stereoselective catalytic activities, cell viabilities, and proliferative abilities. [ABSTRACT FROM AUTHOR]

Chitin is a component of fungal cell walls, and its fragments act as elicitors in many plants. The plasma membrane glycoprotein CEBiP, which possesses LysM domains, is a receptor for the chitin elicitor (CE) in rice. Here, we report that the perception of CE by CEBiP contributes to disease resistance against the rice blast fungus, Magnaporthe oryzae, and that enhanced responses to CE by engineering CEBiP increase disease tolerance. Knockdown of CEBiP expression allowed increased spread of the infection hyphae. To enhance defense responses to CE, we constructed chimeric genes composed of CEBiP and Xa21, which mediate resistance to rice bacterial leaf blight. The expression of either CRXa1 or CRXa3, each of which contains the whole extracellular portion of CEBiP, the whole intracellular domain of XA21, and the transmembrane domain from either CEBiP or XA21, induced cell death accompanied by an increased production of reactive oxygen and nitrogen species after treatment with CE. Rice plants expressing the chimeric receptor exhibited necrotic lesions in response to CE and became more resistant to M. oryzae. Deletion of the first LysM domain in CRXA1 abolished these cellular responses. These results suggest that CEs are produced and recognized through the LysM domain of CEBiP during the interaction between rice and M. oryzae and imply that engineering pattern recognition receptors represents a new strategy for crop protection against fungal diseases. [ABSTRACT FROM AUTHOR]

Background: Terminal restriction fragment length polymorphism (T-RFLP) analysis is commonly used to analyze microbial communities, including oral microflora. However, accurate identification of terminal restriction fragment (T-RF) origins is prevented by unpredictable errors in sizing, thus necessitating the clone library analysis. To minimize sizing errors, we proposed optimizing the size definition of internal standards. Methods: GeneScan-1000 ROX was regenerated as an internal standard by redefining the fragment sizes in terms of molecular weight (MW) based on their mobility relative to 6-carboxyfluorescein (FAM) -labeled restriction fragments derived from the 16S recombinant RNA gene of Porphyromonas gingivalis. Using the new size definition, the average sizing error among eight oral bacteria from six phyla was estimated and compared with that of the conventional method. Microbial communities isolated from saliva were analyzed using the new MW size definition. Bacterial species were assigned to peaks using TRFMA, a Web-based tool for T-RFLP analysis, and compared with those identified in a clone library analysis. Results: Using the new size definition, the average sizing error for 40 T-RFs was drastically reduced from 2.42 to 0.62 bases, and large sizing errors (more than two bases) were eliminated. More than 90% of the total bacterial clones detected by the clone library analysis were assigned by T-RFLP. Conclusion: The size definition of the newly constructed internal standards reduced fragment sizing errors and allowed for accurate assignment of bacteria to peaks by the T-RFLP analysis. This provided a more effective means for studying microbial communities, including the oral microflora. [ABSTRACT FROM AUTHOR]

Discusses the designing of safer genetically engineered organisms for environmental release with specific emphasis on the use of bacterial plasmid addiction systems to limit their survival thus minimizing the anticipated risk. Conceptualization of a novel strategy to construct suicidal genetically engineered microorganisms by exploring/combining the knowledge of different plasmid addiction systems.

Studies molecular cloning, functional complementation in Saccharomyces cerevisiae and enzymatic properties of phosphatidylinositol synthase from the protozoan parasite Toxoplasma gondii. Measurement of mRNA levels; Construction of yeast expression vector containing Toxoplasma gondii cDNA; Disruption of Saccharomyces cerevisiae PIS1 locus.