Just as food labels now tell the content of fat, fiber, vitamins and minerals, food scientists believe the information one day will include all bacteria and fungi in the product.
“Like a nutritional profile, we are creating a microbial profile,” said Dr. Suresh Pillai, Texas AgriLife Research food microbiologist and director of the National Center for Electron Beam Research at Texas A&M University. “We are very interested in how microorganisms behave in food, and we treat all microorganisms as opportunistic pathogens.”
Knowing what microbes are in foods could become increasingly important as researchers continue to discover ways the tiny organisms impact human mental and physical health, he noted.
“Every part of the human body is colonized by very unique microorganisms that are providing functionality to humans. It’s not that they are contaminants. If you removed them, then there would be physiological effects in humans,” said Pillai, who has presented the findings with graduate student Katherine McElhany at the American Society for Microbiology meeting.
He pointed out that microbes predate humans by millions of years. If the history of the Earth was compared to months in a year, he said, microbes would have developed by Feb. 28 and humans would have come along on Dec. 31.
“We are never going to rule the microbes,” Pillai said.
Further, he said, for every one human cell in the world, there are 10 microbes.
With that ratio of bacteria to people, Pillai and colleagues have been studying how these organisms behave in the human body.
One thing that is known, he said, is that bacterial cells communicate via autoinducer or “signalling” molecules that communicate a variety of messages between cells.
“We’re also using a lot of our effort looking at how these organisms communicate with one another in the food,” Pillai said. “For example, if you have two or three cells of Salmonella in orange juice, will all the protein expression in these bacterial cells be similar if the same Salmonella cells were present in apple juice or in ground beef or chicken meat? We really do not have a clear understanding about that.”
One signaling molecule in particular — the AI-2 molecule — has been shown in Pillai’s lab to control a pathogen such as Salmonella, causing it to behave differently when the organism is in different products — in ground beef versus poultry meat, for example.
AI-2 is associated with Salmonella, E. coli, Streptococcus, Clostridium and other such pathogenic bacteria.
Different fatty acids in the products influence AI-2 activity, Pillai pointed out, as did the method in which the food was processed or prepared.
“The poultry meat and ground beef have certain fatty acids in them that actually would moderate the level of AI-2,” he said. “We also found out that the virulence genes respond differently based on how meats are processed — if it’s cooked, uncooked, etc.”
“In other words, the food material the organisms reside in will have a differential effect whether the microbe survives and how virulent it is,” Pillai said.
He said the study implies that the virulence of a potentially pathogenic microorganism can be modified in different foods and substrates.
“Infective doses could vary for the same organism in different foods and substrates and this has important ramifications for microbial risk assessment,” Pillai added.
Not only is this information important for daily food consumption, he said, but potentially could have impact over the lifelong development of people from infancy.
“A question we have is ‘what is the net result of these interactions in terms of how the gastrointestinal tract develops in infants, what happens in adults, how does this impact chronic ailments like obesity?” he said. “At what age are we sentenced to a particular microbiome, or environment of microbes in our systems?”
Information the researchers have gleaned from the study may ultimately help “fingerprint” foods for microbial data, which could be relayed to people for choosing foods that are best for their conditions.