‘A valuable addition to QC’: FDA GutProbe may help verify accurate labelling in commercial probiotics

18-May-2015 - Last updated on 12-May-2016 at 21:42 GMT

A custom DNA microarray may provide a ‘quick, more accurate, and inexpensive’ method for identifying microbials and probiotics in dietary supplements, say the FDA researchers who developed the technique.

Scientists from the FDA’s Center for Food Safety & Applied Nutrition report that the “FDA GutProbe” is able to identify lot-to-lot differences in probiotic products, and may be “useful for routine monitoring of batch variation as part of a 'Good Manufacturing Practices' process”.

The microarray is able to identify specific strains in supplements containing a mixture of probiotics, according to a paper published in the Journal of Applied Microbiology.

Commenting on the significance of the research, Jen Patro and her co-authors wrote: “The FDA GutProbe is an efficient and reliable platform to identify the presence of microbial ingredients and determining microbe differences in dietary supplements. The GutProbe is a fast, rapid method for direct community profiling or food matrix sampling.”

The study was funded by the Center for Food Safety and Applied Nutrition (CFSAN).

IPA: This is ‘interesting’

The method is a new use of an existing technique (the Affymetrix microarray), and a statement from the scientific advisory board of the International Probiotics Association (IPA) described the paper as “interesting”.

“A custom microarray was designed which includes species commonly found in the intestine, food and dietary supplements. The system was found to detect with great accuracy organisms present in test samples,” they told NutraIngredients-USA.

“The advantage of the system is that it analyses a great number of organisms in one assay; thereby saving time. This way it can be checked if a product does indeed contain the organisms it should contain according to the manufacturer. Furthermore, there is an opportunity to detect contaminants. For this purpose, the microarray should maybe be expanded to detect common contaminants.”

Methodological details

probiotics-contains probiotics — "Our data indicated that there were no variations within the lots of all products tested in this study," said the researchers

Patro and her co-workers tested the GutProbe on eight different dietary supplements sold in the US and compared this to the information presented on the labels.

The GutProbe was able to test for a range of bacteria, including 24 Lactobacilli, 18 Bacteroides, 13 Clostridia, eight Bifidobacteriums, five Bacillus, two Enterococci, two Leuconostoc, two Pediococcus and one Lactococcus species, they said. “These strains are represented by 92 whole genomes and 229 plasmids,” they explained.

The results of probe indicated that the custom DNA microarray could indeed identify various species found within dietary supplements, and this could be used to assess labelling information.

While the majority of the supplements tested did match their labels, some mislabeling was identified, such as Lactobacillus helveticus misidentified as Lactobacillus acidophilus, they said.

The scientists also applied the GutProbe to three different lots in order to examine any variability. “Our data indicated that there were no variations within the lots of all products tested in this study except were lot formulation was changed according to the label,” they wrote.

While DNA analysis may show the identity of the strains, it cannot determine the quantity or viability of the strains, added the authors.

Limitations

While the IPA scientific advisory board was positive about the methodology, it did note certain drawbacks: “While the array is able to detect a range of organisms, it will only detect what is provided on the array; though that is still more than what many of the other quality control (QC) techniques do,” it said.

“The technology detects DNA; so, it does not give information on the viability of the organisms; which is essential for probiotics and relevant for contaminants as well. Furthermore, the technique cannot quantify. Finally, not every lab has the ability to handle microarrays; in which case the methodology requires a certain investment, but that is of course always the case with a new technique.

“So, what is the final verdict of this technique? It may be a valuable addition to QC. On its own it is, however, not sufficient. But it can provide a quick first evaluation; are the organisms that are supposed to be there present or not, and are there other organisms present?”

‘IPA welcomes innovative thinking and new applications of methodologies’

In an additional comment, George Paraskevakos, Executive Director of the IPA, told us that the organization welcomes innovative thinking and new applications of methodologies for the probiotic industry. “IPA believes that in order to remain credible amongst regulators and establish deeper consumer confidence, raising the bar for scientific standards and disseminating this message, becomes almost obligatory.

“Advancing the science and understanding of how probiotics work and interact with the host will help root out their benefits and increase acceptance amongst all stakeholders and experts in our industry.”

Source: Journal of Applied Microbiology
Published online ahead of print, doi: 10.1111/jam.12795
“Development and utility of the FDA 'GutProbe' DNA microarray for identification, genotyping and metagenomic analysis of commercially available probiotics”
Authors: J.N. Patro, P. Ramachandran, J.L. Lewis, et al.