Curing of a field strain of Salmonella enterica serovar Infantis isolated from poultry from its highly stable pESI like plasmid.

Salmonella enterica serovar Infantis (S. infantis) is an important emerging pathogen, associated with poultry and poultry products and related to an increasing number of human infections in many countries. A concerning trend among S.

Engineering of methionine-auxotroph via parallel evolution of two enzymes from direct-sulfurylation pathway enables its recovery in minimal medium.

Methionine biosynthesis relies on the sequential catalysis of multiple enzymes. , the main bacteria used in research and industry for protein production and engineering, utilizes the three-step trans-sulfurylation pathway catalyzed by L-homoserine O-succinyl transferase, cystathionine gamma synthase and cystathionine beta lyase to convert L-homoserine to L-homocysteine. However, most bacteria employ the two-step direct-sulfurylation pathway involving L-homoserine O-acetyltransferases and O-acetyl homoserine sulfhydrylase.

Conversion of methionine biosynthesis in Escherichia coli from trans- to direct-sulfurylation enhances extracellular methionine levels.

Methionine is an essential amino acid in mammals and a precursor for vital metabolites required for the survival of all organisms. Consequently, its inclusion is required in diverse applications, such as food, feed, and pharmaceuticals. Although amino acids and other metabolites are commonly produced through microbial fermentation, high-yield biosynthesis of L-methionine remains a significant challenge due to the strict cellular regulation of the biosynthesis pathway.

Development of toxin-antitoxin self-destructive bacteria, aimed for salmonella vaccination.

The most common source of foodborne Salmonella infection in humans is poultry eggs and meat, such that prevention of human infection is mostly achieved by vaccination of farm animals. While inactivated and attenuated vaccines are available, both present drawbacks. This study aimed to develop a novel vaccination strategy, which combines the effectiveness of live-attenuated and safety of inactivated vaccines by construction of inducible self-destructing bacteria utilizing toxin-antitoxin (TA) systems.

Oral subunit SARS-CoV-2 vaccine induces systemic neutralizing IgG, IgA and cellular immune responses and can boost neutralizing antibody responses primed by an injected vaccine.

The rapid spread of the COVID-19 pandemic, with its devastating medical and economic impacts, triggered an unprecedented race toward development of effective vaccines. The commercialized vaccines are parenterally administered, which poses logistic challenges, while adequate protection at the mucosal sites of virus entry is questionable. Furthermore, essentially all vaccine candidates target the viral spike (S) protein, a surface protein that undergoes significant antigenic drift.