Bordetella bronchiseptica, an emerging zoonotic pathogen, infects a broad range of mammalian hosts. B. bronchiseptica-associated atrophic rhinitis incurs substantial losses to the pig breeding industry. The true burden of human disease caused by B. bronchiseptica is unknown, but it has been postulated that some hypervirulent B. bronchiseptica isolates may be responsible for undiagnosed respiratory infections in humans. B. bronchiseptica was shown to acquire antibiotic resistance genes from other bacterial genera, especially Escherichia coli. Here, we present a new B. bronchiseptica lytic bacteriophage—vB_BbrP_BB8—of the Podoviridae family, which offers a safe alternative to antibiotic treatment of B. bronchiseptica infections. We explored the phage at the level of genome, physiology, morphology, and infection kinetics. Its therapeutic potential was investigated in biofilms and in an in vivo Galleria mellonella model, both of which mimic the natural environment of infection. The BB8 is a unique phage with a genome structure resembling that of T7-like phages. Its latent period is 75 ± 5 min and its burst size is 88 ± 10 phages. The BB8 infection causes complete lysis of B. bronchiseptica cultures irrespective of the MOI used. The phage efficiently removes bacterial biofilm and prevents the lethality induced by B. bronchiseptica in G. mellonella honeycomb moth larvae.

Polaromonas sp. str. GM1 is an aerobic, psychrotolerant, heterotrophic member of the Betaproteobacteria and is the only isolate capable of oxidising arsenite at temperatures below 10 °C. Sequencing of the aio gene cluster in GM1 revealed the presence of the aioB and aioA genes, which encode the arsenite oxidase but the regulatory genes typically found upstream of aioB in other members of the Proteobacteria were absent. The GM1 Aio was purified to homogeneity and was found to be a heterodimer. The enzyme contained Mo and Fe as cofactors and had, using the artificial electron acceptor 2,6-dichlorophenolindophenol, a Km for arsenite of 111.70 ± 0.88 μM and a Vmax of 12.16 ± 0.30 U mg(-1), which is the highest reported specific activity for any known Aio. The temperature-activity profiles of the arsenite oxidases from GM1 and the mesophilic betaproteobacterium Alcaligenes faecalis were compared and showed that the GM1 Aio was more active at low temperatures than that of A. faecalis. A homology model of the GM1 Aio was made using the X-ray crystal structure of the Aio from A. faecalis as the template. Structural changes that account for cold adaptation were identified and it was found that these resulted in increased enzyme flexibility and a reduction in the hydrophobicity of the core.

Food preservation is a vital issue on a global scale. It reflects both the need to prevent food spoilage as well as the necessity for reduction in the occurrence of food-borne pathogens. Progress of technology allowed for the development of various techniques that inhibit the growth or activity of food contaminating microbes. In the last few years we saw creation of various types of antimicrobial food packaging systems. They contain active antimicrobial agents immobilized on a material that acts as a food wrap. In this paper we have tested the efficiency of Abeego, a commercially available food wrap, against representatives of different groups of microbes. The Abeego wrap contains natural products such as waxes and oils, which can display antimicrobial activity. We analyzed the ability of the wrap and its components to affect the growth and replication of various groups of microorganisms. We have discovered that the Abeego wrap was capable of significantly inhibiting the viable cell count of bacterial species – both gram positive and gram negative. However no noticeable antifungal or antiviral activity has been observed. This implies that Abeego wrap can act as an efficient mean of inhibiting the spread of food-borne bacterial pathogens, as well as contribute to preventing food spoilage.

We have assembled a collection of 13 psychrophilic ligA alleles that can serve as genetic elements for engineering mesophiles to a temperature-sensitive (TS) phenotype. When these ligA alleles were substituted into Francisella novicida, they conferred a TS phenotype with restrictive temperatures between 33 and 39°C. When the F. novicida ligA hybrid strains were plated above their restrictive temperatures, eight of them generated temperature-resistant variants. For two alleles, the mutations that led to temperature resistance clustered near the 5= end of the gene, and the mutations increased the predicted strength of the ribosome binding site at least 3-fold. Four F. novicida ligA hybrid strains generated no temperature-resistant variants at a detectable level. These results suggest that multiple mutations are needed to create temperature-resistant variants of these ligA gene products. One ligA allele was isolated from a Colwellia species that has a maximal growth temperature of 12°C, and this allele supported growth of F. novicida only as a hybrid between the psychrophilic and the F. novicida ligA genes. However, the full psychrophilic gene alone supported the growth of Salmonella enterica, imparting a restrictive temperature of 27°C. We also tested two ligA alleles from two Pseudoalteromonas strains for their ability to support the viability of a Saccharomyces cerevisiae strain that lacked its essential gene, CDC9, encoding an ATP-dependent DNA ligase. In both cases, the psychrophilic bacterial alleles supported yeast viability and their expression generated TS phenotypes. This collection of ligA alleles should be useful in engineering bacteria, and possibly eukaryotic microbes, to predictable TS phenotypes.O ne aspect of synthetic biology is the development of genetic elements that can be used for genome engineering (1). These elements include promoters (2, 3), transcriptional enhancers (4), transcriptional stop elements (5), riboswitches (6), or site-specific recombinases (7). Some include reporter genes that encode fluorescent proteins, pigments, or odors (8). Others (9, 10) have proposed that essential genes could be a useful class of genetic elements that might be widely used to engineer the limits of viability of a variety of microbes under a specified restrictive condition, such as high temperature. One application of temperature restriction of growth could be in creating bacterial pathogens that are identical to the wild type in every trait except for growth above a defined temperature, such as 35°C. Such pathogens could be used in research, teaching, and diagnostic antigen preparation with minimal chance of causing invasive disease in humans. Another application is in creating attenuated vaccines, where temperature sensitivity is already a well-established approach for attenuation.Essential genes are defined as those that are required for the viability of an organism under all growth conditions (11-13). Biologists try to determine an organism's complement of essential genes for the inherent interest in...