Host-controlled restriction and modification of TP-1C phage and infectious phage DNA occurs in Bacillus stearothermophilus and is subject to control by TP-8 or TP-12 prophage.

Prophage induction in lysogenic Escherichia coli W1709 (iota) was determined for 29 N-nitroso compounds, 13 of their denitrosated derivatives, and 7 hydroxylamino and hydrazino analogues of nitrosamines. Minimal inducing concentrations of 0.1 to 2.0 mug/ml were demonstrated for eight nitrosamidines, and concentrations of 0.5 to 25.0 mug/ml were shown for six nitrosamides. Weak inducing activiti...

The global regulator H-NS of Escherichia coli controls genes related to stress response, biofilm formation and virulence by recognizing curved DNA and by silencing acquired genes. Here, we rewired H-NS to control biofilm formation using protein engineering; H-NS variant K57N was obtained that reduces biofilm formation 10-fold compared with wild-type H-NS (wild-type H-NS increases biofilm format...

Prophage typically are induced to a lytic cycle under stressful environmental conditions or when the host's survival is threatened. However, stress-independent, spontaneous induction also occurs in nature and may be cell density dependent, but the in vivo signal(s) that can trigger induction is unknown. In the present study, we report that acyl-homoserine lactones (AHL), the essential signaling...

Prophages of Helicobacter pylori, a bacterium known to co-evolve in the stomach of its human host, were recently identified. However, their role in the diversity of H. pylori strains is unknown. We demonstrate here and for the first time that the diversity of the prophage genes offers the ability to distinguish between European populations, and that H. pylori prophages and their host bacteria s...

Diarrheic food poisoning by bacteria of the Bacillus cereus group is mostly due to several toxins encoded in the genomes. One of them, cytotoxin K, was recently identified as responsible for severe necrotic syndromes. Cytotoxin K is similar to a class of proteins encoded by genes usually annotated as haemolysin II (hlyII) in the majority of genomes of the B. cereus group. The partially sequence...

Humans play little role in the epidemiology of Escherichia coli O157:H7, a commensal bacterium of cattle. Why then does E. coli O157:H7 code for virulence determinants, like the Shiga toxins (Stxs), responsible for the morbidity and mortality of colonized humans? One possibility is that the virulence of these bacteria to humans is coincidental and these virulence factors evolved for and are mai...

When I was an undergraduate at Caltech, I worked in Bob Edgar’s laboratory on an obscure aspect of phage T4 morphogenesis, which had previously been studied by a little-known South African geneticist, Sydney Brenner [1]. I remember a journal club presented by one of the graduate students in the lab, about the lac repressor binding to DNA. I don’t remember the precise experiments but I know I wa...

Cytolethal distending toxins (CDT) are potent cytotoxins of several Gram-negative pathogenic bacteria, including Escherichia coli, in which five types (CDT-I to CDT-V) have been identified so far. CDT-V is frequently associated with Shiga-toxigenic E. coli (STEC), enterohemorrhagic E. coli (EHEC) O157 strains, and strains not fitting any established pathotypes. In this study, we were the first ...