This Bacterium May Improve Food Security

07/12/2015 09:41 EDT | Updated 07/12/2016 05:59 EDT
A man cuts the good part of a rotten tomato in the dump of Buenos Aires biggest vegetable market Tuesday, May 21, 2002. A four-year-old economic downturn has become the worst recession in Argentine history. The jobless rate has soared to 20 percent, the peso has devalued more than 70 percent against the dollar, and more than one-third of the 36 million people now live in poverty. (AP Photo/Diego Giudice)

There's nothing worse than discovering rotten food. The once pristine source of nourishment has transformed into a stinking, discoloured shell of its former self and is relegated to the trash bin or the organic recycling container. For most of us, this phenomenon simply means a trip back to the grocery store to restore supplies. But in many parts of the world, spoilage is a much greater problem.

Based on information from the Rockefeller Foundation about 1/3 of all food is wasted as a result of spoilage. Finding solutions could improve the quality of life for about a billion people worldwide. It could also help to reduce prices helping to keep more money in our pockets.

Finding solutions has been difficult. Some of the original ideas, such as pesticides have been regarded as anathema. Another once hailed concept using irradiation has only limited value as equipment is not universally available and the cost can be quite high. Another option, antimicrobials has some use but the use of this technique requires specialized labs to make the effective preservatives and has costs some cannot bear.

Some of the major targets for reducing spoilage are microbes including bacteria. In the wild, a variety of species roam effortlessly searching for the next place to thrive. For them, vegetables and fruit are the perfect residence. When they attach, they begin a common process of growth and spread. The result is a large microbial mass called a biofilm. As the microbes continue to grow, they break down the cellular matrix of the food, causing it to turn colour and eventually degrade to slime. Also, as the bacteria feed, they release waste, which can sometimes be noxious to our sensitive nostrils. Within a few days, the once-beautiful food becomes nothing more than a mess.

But there may be a way to preserve foods to ensure a longer shelf life at a reasonable cost. The answer is not physical or chemical, it's microbiological. Using bacteria to preserve foods has been around for millennia in the guise of fermentation. The practice has been for the most part forgotten in Canada thanks to refrigeration and chemical preservatives. Yet in many areas of the world, this routine continues to be one of the best ways to keep food fresh.

The fermentation procedure is essentially the same. A bacterial mix -- sometimes called a starter culture -- is added to foods usually in water or some other liquid. Over time, the bacteria change the nature of the food, adding acidity and a host of antimicrobial compounds. This helps to prevent spoiling bacteria from growing. After a matter of a few hours, days, weeks, or in some cases months, the food is kept fresh and can be enjoyed far later than the usual shelf life.

But there is a requirement with traditional fermentation preventing it from being used en masse for food security. It has to be performed in batches. This significantly reduces the flow of the food continuum and potentially leaves valuable food resources left to spoil while it waits. The process can be upscaled but can never reach the volume needed to sate billions of people.

That may all change for the better. Last week, a team of Malaysian scientists introduced a fermenting bacterium with the ability to protect food without the need for batches. Based on the results of the study, in the future, all that may be needed is a quick spray and the food would be safe from microbial spoilers.

The group decided not to look at fermentation starter cultures but instead at plants known to resist spoiling in the wild. They looked at the bacterial population of one plant, pandan, which is used in Asian cuisine. They found quite a number of different species, many of which are known fermenters. But amongst the population, they found one that was quite unique in that it acted just like a spoiler without the drastic consequences.

The strain is called Lactobacillus plantarum PA21 and in the lab, it not only grew like all other bacteria, but it formed biofilms. This was both new for this bacterium and also opened the door to a novel idea. The bacterium could create a barrier on fruits and vegetables to block out spoiling species. When they tested the concept, they were happy to see on surfaces in the lab, biofilms grew quite well in temperatures similar to that of the Malaysian climate.

This was was only half the goal. The next step was to introduce various species of bacteria to see if the good biofilms would hold strong. Compared to controls without biofilms, the results were dramatic. The spoiling bacteria were either completely eliminated or reduced significantly to safe levels. In essence, at least in the lab, the results provided the promise for future preservation.

While this information was already positive, the authors hinted it could get better. They attempted to put other factors into the bacterium using genetic modification. They were successful suggesting other preservative factors, such as antimicrobials could one day be introduced to make them even more powerful.

In the context of food security, the team suggested L. plantarum PA21 represents a bright future. The bacterium is easy and inexpensive to grow, can be manipulated genetically, and also can be used worldwide as it has no pathogenic properties. With further testing, the perfect microbial preserver may be developed and then eventually mass produced. If all goes well, it may one day end up not only on crops in countries suffering from food shortages, but perhaps even the local Canadian grocery store.


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