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The molecular characteristics of Yersinia ruckeri such as total proteins (TP), outer membrane proteins OMP) and lipopolysaccharides (LPS) in 34 isolates from rainbow trout farms in Tehran, Mazandaran and Zanjan provinces were determined, using SDS-PAGE method. The molecular weight (MW) for TP of all bacterial isolates was mostly less than 100 KD with a banding density in range 28 to 100 KD. Also, protein pattern of OMP consisted of three major bands with MW of 28-35 KD (two bands) and 10-17 KD (one band) plus some minor bands with MW of 48-75 KD and 17-28 KD. In addition, the LPS pattern of all bacterial isolates were less than 130 KD with the most band density in range 28-100 KD. These results show that the banding profile of TP, OMP and LPS of all isolates of Y. ruckeri were identical, demonstrating minimum heterogeneity among Iranian isolates of Y. ruckeri. Therefore, it is feasible for the formulation of a monovalent vaccine to yersiniosis in future.

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Isolates were identified by molecular and morphological tests, including coleopteran-specific cry genes in the Iranian native Bacillus thuringiensis collection. Spherical and irregular shapes were observed to be the most frequent shapes using Coomassie brilliant blue staining. PCR analysis with universal and specific primer pairs was used to detect coleopteran-specific cry genes such as cry1I, cry3, cry7, cry18, and cry26. All the isolates contained at least one active coleopteran-cry gene, while the most abundant isolates had cry26 and cry18 genes. The patterns of protein size were characterized in addition to their insecticidal activity against third-instar larvae of Tribolium castaneum. Protein profiles produced bands that varied from 14-180 kDa. Four native isolates containing coleopteran-active cry genes displayed higher activity against T. castaneum larvae than B. thuringiensis subspecies galleriae as a reference strain. The median lethal concentration (LC₅₀) of the most pathogenic isolate, PS1078, was 2.72 × 10⁶ spores/ml. Its 16S rDNA gene sequence analysis demonstrated similarity to B. thuringiensiss subspecies galleriae. The characterization of isolates provided useful data for selecting new isolates to expand novel bio-insecticidal products.