Pet Food and Microbiology

Why is it important to test Pet Food for microbiology?

In the past few years there have been multiple outbreaks related to pet food affecting the health of both pets and humans.  Most people associate Salmonella as a bacterium linked to food borne illness in people food, but in recent years there have been quite a few outbreaks of Salmonella in pet food that has also affected humans.  The most concerning aspect is that it primarily caused illness in small children.  It was not believed to be caused by the children eating the dog food, but having interactions with the dog.  After it was discovered that the outbreak was caused by tainted dog food, over 23,000 tons of pet food was recalled, and when the outbreak continued, the plant that produced the tainted dog food was closed down.  There was also a pet food recall based on an aflatoxin contamination.  The Center for Disease Control (CDC) categorizes aflatoxin as a naturally occurring fungal toxin that contaminates maize and other types of crops during production, harvest storage or processing1.  The aflatoxin outbreak was linked to the death of over a hundred pets.  In the past year Kroger stores recalled a wide variety of pet foods due to a possible contamination caused by aflatoxin2.

However, it is more effective to test for indicator organisms rather than to test for pathogens such as Salmonella.  Indicator organisms are used to measure potential fecal contamination of environmental samples. The presence of coliform bacteria, such as E. coli, is a common indicator of fecal contamination. Indicator organisms are typically used to demonstrate the potential presence or absence of groups of pathogens. The use of indicators is attractive because it reduces the complexity and cost of analyzing

Indicator microbes are generally selected for the following reasons:

1) They are initially abundant in the matrix to be assayed.

2) A relatively rapid, accurate, and cost effective analytical method for enumerating the indicator exists or can be readily developed.

3) A reasonably strong correlation exists between the presence/absence of the indicator and a particular pathogen or group of pathogens. The strength of the correlation will determine the effectiveness and accuracy of the indicator as a measure of pathogen occurrence.

In pet food testing is conducted for Enterobacteriaceae or fecal coliform as indicator of fecal contamination and yeast and mold as indicators for general quality and aflaxoins.

What are the advantages of the BioLumix system?

Using the BioLumix system will allow the customers to test their products not only for Salmonella and yeast/molds, but also for indicator organisms such as coliforms, fecal coliforms, Enterobacteriaceae and more.  Indicator organisms can be used to pet food manufacturing to cleanliness and sanitary issues within the facility.  Also the presence of the organisms can affect appearance, taste and texture of the pet food.  The BioLumix system can save time when testing pet food products for Yeast and Mold, instead of taking five days using traditional plates, the BioLumix system will give the same results in under 48 hours.  This can help the manufacturers to avoid a potential aflatoxin contamination by knowing if their product contains any amount of mold.  Detecting fecal coliforms is even faster and saves even more money using the BioLumix system.  Instead of running an MPN assay which will require up to 5 days of testing as well as 9 tubes of LTB and up to 9 tubes of EC Media to wait for confirmation of a positive fecal coliform.  Finally, the last confirmation step is to streak the positive EC Media to L-EMB agar plates; the BioLumix system instead requires one test vial and 1ml of the sample in order to detect a level as low at <10 cfu/gram, and can give results in under 24 hours.  Similarly, the Enterobacteriaceae test in BioLumix requires one vial instead of multiple MPN tubes required by the European method.

BioLumix Pet Food Study

BioLumix recently conducted a study of different store bought pet foods, ranging from dry dog food samples to wet (oil based) samples.  All samples matched the results for Yeast/Mold, Enterobacteriaceae, Total Aerobic Count, E. coli and fecal coliforms when comparing between the BioLumix System and traditional plating methods.  Since there are no specifications by AAFO or FDA for indicator organisms in pet foods the levels tested for Enterobacteriaceae were based on European standards for pet food.   The products were processed and tested using FDA-BAM methods3.  Only one sample came up positive for fecal coliforms, results of the BioLumix vial matched the MPN results.  Two of the samples had counts >10 cfu/g for Enterobacteriaceae and were the only ones that were above the specification level of cfu’s of the manufacturer. 

The BioLumix system detects optical changes in the test vial, presenting results of the assays as soon as detections occur with no need for involvement of an operator or a microbiologist, providing significant savings on laboratory labor. Any out-of-spec samples are flagged in red, demanding attention. The greater the contamination level, the faster the result, ensuring a rapid warning of poor-quality raw materials, finished products or any equipment line issues.

The BioLumix System showed a high correlation between the instrument results and the BAM methodology.  It simplified the microbiological testing, offers a significant reduction in time to obtain results and reduces hands-on labor due to its automation and simplicity of use.  The time to results for bacteria was hours rather than days while yeast and mold required only 48 hours instead of 5 days. 


Fast, Accurate Dairy Microbiology Testing For Yeast and Mold

Cultured dairy products are the fastest growing area of consumer dairy consumption.1 Rapid dairy microbiology testing for yeast and mold, the most common contaminants in these products, is critical to the industry and consumer safety. Yeast and mold can cause substantial economic losses and produce harmful metabolites.2

Traditional dairy microbiology testing requires 5 days to complete using the plate count methodology. Sending samples to outside labs adds to the cost and time of testing. A microbiological system developed by BioLumix has cut dairy microbiology testing time to as little as 24-48 hours. With the BioLumix microbiological system, manufacturers can streamline existing dairy microbiology testing operations or internalize their outsourced testing for reduced costs and improved efficiency.

In-house microbiology testing with the BioLumix system is simple. Samples are placed in ready-to-use, disposable vials that contain a transparent solid sensor at the bottom. These sensors detect the production of CO2 by all yeasts and molds. This means that if yeasts and molds begin to grow in the medium above the sensor, they will produce CO2 that will diffuse into the sensor and change the sensor’s color. Only gases can penetrate the sensor, which means the optical readings cannot be masked by any liquids, microorganisms, and/or particulate matter.

The BioLumix microbiological system can then detect any optical changes, presenting the results of the assays as soon as detections occur with no need for involvement of an operator or a microbiologist, providing significant savings on laboratory labor. Any out-of-spec samples are flagged in red, demanding attention. The greater the contamination level, the faster the result, ensuring a rapid warning of poor-quality raw materials, finished products or any equipment line issues. The speed of these dairy microbiology results ensure that dairy product manufacturers don’t have delays from testing so they can move products from the warehouse to the marketplace quickly and without premature spoilage.

A recent dairy microbiology study assessed the BioLumix microbiological system with various cultured dairy products that were clean, naturally contaminated, or inoculated with different yeast or mold strains. This included products with high levels of active starter culture or probiotics.3 The BioLumix microbiological system demonstrated 100% accuracy in detecting over 100 different combinations of clean contaminant products, which was comparable to plate count methodology, the current standard in dairy microbiology. However, the BioLumix microbiological system reduced detection time from 5 days to 24 hours for most yeast and 48 hours for mold.

The BioLumix microbiological system simplifies and automates your laboratory procedures by delivering shorter sample preparation, automated real-time communication, fast product release, and early warning of contamination, as well as automated data entry, data archiving, report generation and product release. With reliable dairy microbiology results in just 24-48 hours, dairy manufacturers can focus on efficiency and product quality. For a full reprint of the study or any further information on the BioLumix microbiological system, visit or call 1-734-984-3100.


1. Cogan TM, et al. Advances in starter cultures and cultured foods. J Dairy Sci. 2007;90:4005-4021.

2. Hussein HS, Brasel JM. Toxicity, metabolism and impact of mycotoxins on human and animals. Toxicology. 2001;167:101-134.

3. Eden RF, Brideau R. Rapid automated detection of yeast and molds in cultured dairy products. International Association of Food Protection Annual Meeting 2009.

Karen F. Vieira, Ph.D.

A Rapid+Easy Method for Microbiological Testing of Dietary Supplements Complying w/cGMP & USP

Nutraceutical and dietary supplements consist of vitamin and mineral supplements, amino acids, herbs, essential oils, enzymes, homeopathic remedies and other natural products. For years dietary supplements have been unregulated by the U.S. Food and Drug Administration (FDA). In 1994 the Dietary Supplement Health and Education Act (DSHEA) was enacted, which stated that dietary supplement manufacturers must ensure supplements’ safety before marketing them.1

In 2007 the FDA issued the final rule for the implementation of current good manufacturing practices (cGMP) for supplements. 2 The FDA 21 Code of Federal Regulations (CFR) Part 111 required the implementation for large manufacturers in June 2008 and that by June 2010 all dietary supplement manufacturers test their products for identity, purity, contaminants and microbiology quality assurance, like pharmaceutical companies do. 3

To meet these new requirements, dietary supplement manufacturers must test their products for microbiology quality assurance and generate a certificate of analysis for each batch. To do this they either send product samples to contract laboratories for USP microbiological testing or test them internally. To reduce the time to get results, increase efficiency and reduce expenses, BioLumix offers a fast, automated, cost effective way for nutritional and dietary supplement companies to perform USP microbiological testing. The BioLumix system is an in-house method to easily perform accurate and automated microbiology quality assurance assays on finished products, in-process and raw materials and environmental work surfaces. This system can cut quarantine time for microbial testing from 5-6 days to 35-48 hours.

Samples are placed in ready-to-use, disposable vials inserted into an instrument that determine the microbial quality of the product. The system can perform all FDA-required tests such as total aerobic count, yeast and mold count, Enterobacterial count, and objectionable organisms such as E. coli, S. aureus, Salmonella and P. aeruginosa. The BioLumix testing system also includes a step-by-step process to optimize the installation, operation and performance so that it is easy for nutraceutical and dietary supplement manufacturers to do microbiology quality assurance.

The BioLumix testing system allows for faster sample preparation plus provides automated real-time communication, fast product release and early warning of contamination via USP microbiological testing. Because the BioLumix system is automated and its software generates the results, it is not necessary to have an employee dedicated solely to running the microbiology quality assurance tests. This makes the BioLumix system a cost-effective way for dietary supplement manufacturers to meet the new FDA cGMP requirements for microbiological testing. For more information on the BioLumix cGMP USP microbiological testing system, visit or call 1-734-984-3100.


1. Dietary supplements. FDA Web site.

2. FDA Issues Dietary Supplements Final Rule. FDA Web site.

3. FDA 21 CFR part 111. FDA Web site.

Karen F. Vieira, Ph.D.