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Background: Salmonella enterica is the etiological agent of salmonellosis, with a high infection rate worldwide in Mexico, ST213 genotype of S. enterica ser. Typhimurium is displacing the ancestral ST19 genotype. Bacterial cytoskeleton protein complex MreBCD plays an important role in S. enterica pathogenesis, but underlying mechanisms are unknown. Results: In this study, 106 interactions among MreBCD and 15 proteins from S. Typhimurium Pathogenicity Islands 1 (SP-I) and 2 (SP-2) involved in both bacterial virulence and stress response were predicted in ST213 and ST19 genotypes, of which 12 interactions were confirmed in vitro. In addition, gene cluster analysis in 100 S. Typhimurium genomes was performed for these genes. Results and Conclusion: The in silico and in vitro results showed a novel MreBCD interactome involved in regulating pathogenesis and stress response through interactions with virulence factors located at SPI-1 and SPI-2. Furthermore, both pseudogene presence and sequence variations in four tested proteins between genotypes resulted in differential interaction patterns involved in Salmonella motility and survival in eukaryotic cells, which could explain the replacement of ST19 by ST213 in Mexico.

The present work looks at the effectiveness of microbound spray-dried feed (MB-SD) elaborated with two phycocolloids, sodium alginate (ALG) and kappa-carrageenan (KAPACA), and no binder at all (SL). Feeding trials were carried out on larval Pacific white shrimp Litopenaeus vannameifrom wild broodstock. Nauplii were stocked in 1.5-L round-bottomed flasks at a rate of 100 larvae/tank. Thirty thousand cells/mL (70% Chaetoceros muelleriand 30% Isochrysis galbana)were added to the artificial feed treatments as a single dose of live algae (SDLA) administered on the first day of the experiment. The MB-SD was given at 6-16 mg/L daily every 4 h from 0800 to 2000 hours. Water was not exchanged during the 10-d experimental period. The MB-SD with KAPACA gave the highest survival (61 ± 4.6%), good mean individual dry weight (104 ± 20.9 mg), and high metamorphic rate (81 ± 14%), followed by MB-SD with ALG (56.9 ± 4.1% survival; 65 ± 10% metamorphic rate) and MB-SD with SL (49.2 ± 6.2% survival; 76 ± 12% metamorphic rate). The latter feeds did not show a significant difference; however, they were slightly better than live food (algae plus brine shrimp Artemiasp.; 51.3 ± 7.9% survival; 52 ± 8% metamorphic rate). The MB-SD with KAPACA provided good larval survival and growth and could be used in experimental larviculture.