PHAGE TECHNOLOGY-ANOTHER WEAPON AGAINST LISTERIA CONTAMINATION

Bacteriophage are viruses which can kill bacteria through infecting the latter. Wherever there is a colony of bacteria, phages are likely to be seen acting as a check on their uncontrolled proliferation. Phages inject their genetic material into the bacterial cell and hijack their metabolic system leading to their eventual death of the host. It has been reported that phages were extensively used in the erstwhile Soviet Union against pathogens successfully, as an alternative to antibiotics, though as a therapy it never emerged out side this region. Realizing that Listeria contamination is threatening the food markets in some of the developed countries, attempts to use phages against this deadly pathogen resulted in preparations containing the phage for effectively decontamination of surface areas in many solid foods without affecting the sensory quality of the food treated and posing no safety problem to the consumer. With approvals from safety authorities in many countries, phage technology is likely to emerge as a significant tool to fight food poisoning episodes involving food pathogens in the coming years. Here is a take on this latest development in food processing.     

Food Standards Australia New Zealand (FSANZ) has approved Listex P100 as a processing aid against Listeria monocytogenes, making Listex the first phage for product safety approved in Australia and New Zealand. The phage is produced by Dutch company Micreos. According to FSANZ's approval report: * The safety assessment did not identify any public health and safety concerns associated with using Listex P100 to treat food. * It is effective at reducing levels of Listeria monocytogenes on the surface of solid RTE foods evaluated. * There is no appreciable ongoing technological function when it is applied to the surface of various solid RTE foods, therefore it fits into the category of processing aids. This is consistent with international approaches.  * There were no measures that would be more cost effective than Listex P100. "FSANZ's decision marks an important step in the acceptance and appreciation of phage technology," said Mark Offerhaus, CEO of Micreos. "The review process was thorough, transparent and involved all stakeholders; an example of how new - and suitable - technology should be brought to market." Following approvals in the USA, Canada and the Netherlands, Micreos applied for approval of Listex in Australia and New Zealand. Easy to apply, Listex is sprayed onto the surface of food products during processing, killing Listeria without any sensory or other effects.

With many multi drug resistant bacteria emerging during the last few years, world is not seeing any new antibiotics being developed that can fight diseases caused by increasingly virulent and rugged bugs evolving through mutation. As phages occur widely they provide an answer to the prayer by human beings to develop newer technologies against diseases which do not respond to existing antibiotics. Sea water is supposed to be one of the richest sources of phages and it is possible that man may increasingly turn to this source to develop a variety of phage based technologies to fight human and animal diseases in the coming years.

V.H.POTTY
http://vhpotty.blogspot.com/
http://foodtechupdates.blogspot.com

ENEMY'S ENEMY IS A FRIEND?-THE PHAGE THERAPY

The very name of virus evokes fear in the minds of people and deploying these vectors for crop protection and food preservation can attract adverse reaction from the consumers.The most recent viral pandemic in the form of H1N1 virus or Swine Flu virus is fresh in the memory of the world which increased the sense of apprehension about the dangers of viral vectors. Some recent research studies have brought out the benefit of using phage particles for improving yield and counteracting bacterial diseases that affect the crops like tomato which are well documented. But using the phages for food preservation may be some what far fetched as far as the consumers are concerned. Against this background clearance given for use of phages to neutralize the infection from Listeria monocytogenes by safety authorities in some countries could be a desperate move to control wide spread contamination of meat products by this pathogen. Probably the stubborn persistance of Listeria even at refrigerated temperatures must have prompted agencies to provide another tool in the hands of processors to outwit this much feared pathogen.

The Food and Drug Administration has approved phages for use in foods – but only against Listeria monocytogenes, notes food microbiologist Ipek Goktepe of North Carolina Agricultural and Technical State University in Greensboro. And these products find use primarily on meat and deli products, she added. But that's not bad, since Listeria is one of the most common food-poisoning agents. And a particularly recalcitrant one since it happily grows at refrigerated temperatures. Goktepe reported new data showing that Listeria phages aren't uniformly effective in protecting every contaminated food to which they're applied. Food producers would like to see at least a "4 log" reduction in bacteria – that is, a reduction to one ten-thousandth of the starting population of bugs. In some of Goktepe's tests, she may see a three log reduction or less.One recent success: An E. coli phage that targets O157:H7 strains killed a huge share of these bacterial cells that had been growing on loose lettuce and spinach leaves. When the phages were applied in a moist mist, Goktepe says, "We achieved a 3 to 7 log reduction – and that's a lot. We were not expecting that," she says. "Usually a 4 log reduction is considered very significant." She cautions that the big bacterial drop occurred under fairly ideal conditions, such as at 3 °C, a good refrigerator's temperature. Raise the leafy greens' temperature to 10 °C (about 50 °F) and the phage delivered only a 2 to 5 log drop in E. coli numbers.

The phage treatment against both Listeria and E.coli 0157:H7 opens up new avenues for protecting foods against serious microbial contaminants and it should be possible to evolve species-specific phages for widespread use by the industry. Phages occur in abundance in soil, water,sewage,feces,retail foods, process plant effluents from which high titer purified lysates can be made. Most studies have concentrated on Salmonella, Listeria. Campylobacter and Enterogenic E.coli. Typical applications include pre and post harvest spraying on animals like chickens, piglets, calves and lambs. Use of phages in refrigerated foods like fruits, dairy products, poultry products and meat has been found to be good bio-control strategy for extending their shelf life. The technique is self perpetuating, highly discriminatory, natural and cost-effective. Limitation of the phage technology include limited phage range, requirement of threshold number, phage resistant mutants and potential for transduction of undesirable characteristics from one strain to another. How far the technology can be made acceptable to the consumer is a critical question that does not have an answer to day.

V.H.POTTY
http://vhpotty.blogspot.com/
http://foodtechupdates.blogspot.com