Tuesday, January 15, 2013
Bacteriophages and their role in food safety.
Bacteriophages and their role in food safety.
2012
Source
Institute for Biotechnology and Bioengineering (IBB), Centre for Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
Abstract
The interest for natural antimicrobial compounds has increased due to alterations in consumer positions towards the use of chemical preservatives in foodstuff and food processing surfaces. Bacteriophages fit in the class of natural antimicrobial and their effectiveness in controlling bacterial pathogens in agro-food industry has led to the development of different phage products already approved by USFDA and USDA. The majority of these products are to be used in farm animals or animal products such as carcasses, meats and also in agricultural and horticultural products. Treatment with specific phages in the food industry can prevent the decay of products and the spread of bacterial diseases and ultimately promote safe environments in animal and plant food production, processing, and handling. This is an overview of recent work carried out with phages as tools to promote food safety, starting with a general introduction describing the prevalence of foodborne pathogens and bacteriophages and a more detailed discussion on the use of phage therapy to prevent and treat experimentally induced infections of animals against the most common foodborne pathogens, the use of phages as biocontrol agents in foods, and also their use as biosanitizers of food contact surfaces.
Labels: antimicrobial compounds, bacteriophages, biocontrol, biosanitizers, food safety, USDA, USFDA
# posted by Pat O'Connor @ 7:47 AM
Friday, November 09, 2012
Viruses evolve to prevent bacterial hosts from committing suicide
Viruses evolve to prevent bacterial hosts from committing suicide
Nov 9, 2012
University of Cambridge researchers have discovered an extraordinary way that bacterial parasites prevent their hosts from killing themselves to protect the wider colony.
Nov 9, 2012
University of Cambridge researchers have discovered an extraordinary way that bacterial parasites prevent their hosts from killing themselves to protect the wider colony.
Researchers funded by BBSRC discovered that a strain of the potato soft rot and blackleg bacterium Pectobacterium atrosepticum (AKA Erwinia) had evolved to commit suicide in the presence of certain viral parasites, known as bacteriophages, to limit the spread of viral infection in the wider bacterial population.
Some mutant bacteriophages have evolved to stop their hosts from committing suicide.
Image: iStockphoto, Thinkstock 2012
Image: iStockphoto, Thinkstock 2012
The bacterial cells in a population that commit "suicide" by dying prematurely can be viewed as acting "altruistically", giving up their lives to prevent viral replication in siblings in the rest of the culture, in a process called abortive infection.
The paper, Viral Evasion of a Bacterial Suicide System by RNA-Based Molecular Mimicry Enables Infectious Altruism, published in PLoS Genetics on October 18 2012, also identified how the evolutionary arms race had produced low numbers of bacteriophage mutants that could suppress bacterial suicide in infected cells. These rare mutants (from a new transducing bacteriophage of the Myoviridae family) had evolved to produce an RNA antitoxin similar to that normally manufactured by the bacteria to suppress the lethality of the endogenous toxin, thus evading the suicide defence mechanism. By producing the mimic antitoxin, the virus could continue replicating without becoming a victim of the host's defensive system.
The mutant bacteriophage was also able to transfer DNA encoding the defense system to a new bacterial host. In doing so it may have indirectly created populations of host cells inside which it could successfully replicate while potentially providing the new host with better protection from competing viral predators.
Professor George Salmond, deputy head at Cambridge University's Department of Biochemistry, said: "This work highlights the incredibly dynamic world of adaptive co-evolution in bacteria and their viruses. The emergence of an RNA-based molecular mimicry in the virus to suppress bacterial suicide is an exciting observation.
"Furthermore, multiple alternative and novel routes, through which different bacteriophages may evolve to evade abortive infection, remain to be discovered. Because the bacteriophage investigated can pick up DNA from one bacterium and transfer it to a new host, this meant that escape mutants might be able to transfer the abortive infection system to other hosts - and that was confirmed. In effect, this could be viewed as an example of 'infectious altruism' - with a virus acting as a vector to transmit an anti-viral defense system between bacteria.
"Hypotheses about the molecular evolution of the "altruistic" trait, and possible adaptive impacts and fitness consequences (for both virus and bacterial host) can now be formally tested."
Labels: bacteria, bacterial death, bacteriophages, parasites, RNA antitoxin, virus
# posted by Pat O'Connor @ 7:51 AM
Monday, June 18, 2007
Bacteriophages: an appraisal of their role in the treatment of bacterial infections.
Bacteriophages: an appraisal of their role in the treatment of bacterial infections.
Int J Antimicrob Agents. 2007 Jun
Hanlon GW.
School of Pharmacy and Biomolecular Sciences, University of Brighton, Moulsecoomb, Brighton BN2 4GJ, UK.
Bacteriophages were first used successfully to treat bacterial infections a decade before penicillin was discovered. However, the excitement that greeted those initial successes was short-lived, as a lack of understanding of basic phage biology subsequently led to a catalogue of clinical failures. As a consequence, bacteriophage therapy was largely abandoned in the West in favour of the newly emerging antibiotics.
Now, as the problem of antibiotic resistance becomes ever more acute, a number of scientists and clinicians are looking again at bacteriophages as a therapeutic option in the treatment of bacterial infections. The chances of success second time round would appear to be much better given our current extensive knowledge of bacteriophage biology following their important role in underpinning the advances in molecular biology.
We also have available to us the experience of nearly 80 years of clinical usage in the countries of the former Soviet Union and Eastern Europe as well as a political climate that encourages sharing of that knowledge.
This review outlines those features of bacteriophages that contribute to their utility in therapy and explores the potential for their re-introduction into Western medicine. An abundance of clinical evidence is available in the Soviet literature but much of this is technically flawed and a more realistic appraisal of the clinical value of phages can be obtained from animal studies conducted in the West. As interest in bacteriophages increases, a number of companies throughout the world have begun investing in phage technology and this has led to novel approaches to therapy, some of which will be discussed.
PMID: 17566713 [PubMed - as supplied by publisher]
Int J Antimicrob Agents. 2007 Jun
Hanlon GW.
School of Pharmacy and Biomolecular Sciences, University of Brighton, Moulsecoomb, Brighton BN2 4GJ, UK.
Bacteriophages were first used successfully to treat bacterial infections a decade before penicillin was discovered. However, the excitement that greeted those initial successes was short-lived, as a lack of understanding of basic phage biology subsequently led to a catalogue of clinical failures. As a consequence, bacteriophage therapy was largely abandoned in the West in favour of the newly emerging antibiotics.
Now, as the problem of antibiotic resistance becomes ever more acute, a number of scientists and clinicians are looking again at bacteriophages as a therapeutic option in the treatment of bacterial infections. The chances of success second time round would appear to be much better given our current extensive knowledge of bacteriophage biology following their important role in underpinning the advances in molecular biology.
We also have available to us the experience of nearly 80 years of clinical usage in the countries of the former Soviet Union and Eastern Europe as well as a political climate that encourages sharing of that knowledge.
This review outlines those features of bacteriophages that contribute to their utility in therapy and explores the potential for their re-introduction into Western medicine. An abundance of clinical evidence is available in the Soviet literature but much of this is technically flawed and a more realistic appraisal of the clinical value of phages can be obtained from animal studies conducted in the West. As interest in bacteriophages increases, a number of companies throughout the world have begun investing in phage technology and this has led to novel approaches to therapy, some of which will be discussed.
PMID: 17566713 [PubMed - as supplied by publisher]
Labels: bacterial infections, bacteriophages
# posted by Pat O'Connor @ 10:49 AM
Friday, April 06, 2007
Targeted drug-carrying bacteriophages as anti bacterial nanomedicines.
Targeted drug-carrying bacteriophages as anti bacterial nanomedicines.
Antimicrob Agents Chemother. 2007 Apr 2
Department of Molecular Microbiology and Biotechnology, The George S. wise faculty of Life Sciences, and Department of Organic Chemistry School of Chemistry, Tel-Aviv University, Ramat Aviv 69978, Israel.
While the resistance of bacteria to traditional antibiotics is a major public health concern, the use of extremely potent antibacterial agents is limited by their lack of selectivity. As in cancer therapy, anti bacterial targeted therapy could provide an opportunity to re-introduce toxic substances to the anti-bacterial arsenal. A desirable targeted anti-bacterial agent should combine binding specificity, a large drug payload per binding event and a programmed drug release mechanism. Recently we presented a novel application of filamentous bacteriophages as targeted drug carriers that could partially inhibit the growth of Staphylococcus aureus bacteria.
This partial success was due to limitations of drug-loading capacity that resulted from the hydrophobicity of the drug. Here we present a novel drug conjugation chemistry which is based on connecting hydrophobic drugs to the phage via aminoglycoside antibiotics that serve as solubility-enhancing branched linkers. This new formulation allowed a significantly larger drug-carrying capacity of the phages resulting in a drastic improvement in their performance as targeted drug carrying nanoparticles. As an example for a potential systemic use for potent agents that are limited for topical use, we present antibody-targeted phage nanoparticles that carry a large payload of the hemolytic antibiotic chloramphenicol connected through the aminoglycoside neomycin.
We demonstrate complete growth inhibition towards the pathogens Staphylococcus aureus, Streptococcus pyogenes and Escherichia coli with an improvement in potency by a factor of approximately 20,000 as compared to the free drug.
Antimicrobial Agents and Chemotherapy
Antimicrob Agents Chemother. 2007 Apr 2
Department of Molecular Microbiology and Biotechnology, The George S. wise faculty of Life Sciences, and Department of Organic Chemistry School of Chemistry, Tel-Aviv University, Ramat Aviv 69978, Israel.
While the resistance of bacteria to traditional antibiotics is a major public health concern, the use of extremely potent antibacterial agents is limited by their lack of selectivity. As in cancer therapy, anti bacterial targeted therapy could provide an opportunity to re-introduce toxic substances to the anti-bacterial arsenal. A desirable targeted anti-bacterial agent should combine binding specificity, a large drug payload per binding event and a programmed drug release mechanism. Recently we presented a novel application of filamentous bacteriophages as targeted drug carriers that could partially inhibit the growth of Staphylococcus aureus bacteria.
This partial success was due to limitations of drug-loading capacity that resulted from the hydrophobicity of the drug. Here we present a novel drug conjugation chemistry which is based on connecting hydrophobic drugs to the phage via aminoglycoside antibiotics that serve as solubility-enhancing branched linkers. This new formulation allowed a significantly larger drug-carrying capacity of the phages resulting in a drastic improvement in their performance as targeted drug carrying nanoparticles. As an example for a potential systemic use for potent agents that are limited for topical use, we present antibody-targeted phage nanoparticles that carry a large payload of the hemolytic antibiotic chloramphenicol connected through the aminoglycoside neomycin.
We demonstrate complete growth inhibition towards the pathogens Staphylococcus aureus, Streptococcus pyogenes and Escherichia coli with an improvement in potency by a factor of approximately 20,000 as compared to the free drug.
Antimicrobial Agents and Chemotherapy
Labels: anti bacterial nanomedicines, bacteriophages, escherichia coli, Staphylococcus aureus, Streptococcus pyogenes
# posted by Pat O'Connor @ 5:08 AM
