Genetic Diversity and Phylogeny of Antagonistic Bacteria against Phytophthora nicotianae Isolated from Tobacco Rhizosphere

The genetic diversity of antagonistic bacteria from the tobacco rhizosphere was examined by BOXAIR-PCR, 16S-RFLP, 16S rRNA sequence homology and phylogenetic analysis methods. These studies revealed that 4.01% of the 6652 tested had some inhibitory activity against Phytophthora nicotianae. BOXAIR-PCR analysis revealed 35 distinct amplimers aligning at a 91% similarity level, reflecting a high degree of genotypic diversity among the antagonistic bacteria. A total of 25 16S-RFLP patterns were identified representing over 33 species from 17 different genera. Our results also found a significant amount of bacterial diversity among the antagonistic bacteria compared to other published reports. For the first time; Delftia tsuruhatensis, Stenotrophomonas maltophilia, Advenella incenata, Bacillus altitudinis, Kocuria palustris, Bacillus licheniformis, Agrobacterium tumefaciens and Myroides odoratimimus are reported to display antagonistic activity towards Phytophthora nicotianae. Furthermore, the majority (75%) of the isolates assayed for antagonistic activity were Gram-positives compared to only 25% that were Gram-negative bacteria

The mid-infrared instrument for the James Webb space telescope, II: design and build

Instrumentatio

Constitutive modeling of strain-dependent bond breaking and healing kinetics of chemical Polyampholyte (PA) gel

A finite strain nonlinear viscoelastic constitutive model is used to study the uniaxial tension behaviour　of a chemical Polyampholyte (PA) gel. This PA gel is cross-linked by chemical and physical bonds.　Our constitutive model attempts to capture the time and strain dependent breaking and healing kinetics of physical bonds. We compare model prediction with uniaxial tension, cyclic and relaxation tests. Material parameters in our model are obtained by least squares optimization. These parameters gave fits that are in good agreement with the experiments