Is This The Right Starter Culture? The RiboPrinter® Microbial Characterization System Has the Answer


Food manufacturers can only control their products if ingredients are just what the company ordered. How can they be sure? Accurate microbial analysis is the answer and genetics-based tests are the key to finding it.

Case in point: The cost benefits of buying starter cultures rather than creating them in-house appealed to a meat products manufacturer until the company realized it may have lost control of a crucial ingredient.

When the sensory quality of the company’s raw, fermented goods began declining significantly, the producer made a detailed analysis of each item in the product ingredients. Among the ingredients was an important starter culture used in the fermentation process. The producer had been buying a range of cultures from a reputable supplier for many years and the make-up of the mixed starter in question was specified: Micrococcus species, Lactobacillus and Staphylococcus carnosus each in quantities of greater than 109 colony-forming units (cfu)/gram. S. carnosus in particular gives a unique flavor to meat.

Profiling the Starter Culture

Assessing the culture and its quality required an in-depth profile of each item. Authenticating the culture was difficult using traditional biochemical methods that gave only subjective analysis and couldn’t differentiate strains definitively.

Samples of the Staphylococcus cultures were turned over to the DuPont™ RiboPrinter® System for scrutiny. The RiboPrint pattern for Staphylococcus carnosus (see Figure 1) could be linked to samples of Staphylococcus, but other laboratory tests showed that the organism was present only at 0.01% of the needed concentration. In addition other species of Staphylococci that had not been requested were present in much higher numbers. Samples of these unwanted organisms were matched to RiboPrint patterns for Staphylococcus cohnii and Staphylococcus saprophyticus.

Correcting the Formula

With this information in hand, the meat products manufacturer challenged the culture supplier on the formulation. The supplier admitted running into problems getting high yields of the needed Staphylococcus carnosus. The low concentrations of S. carnosus found in the starter culture confirmed the organism’s viability problems.

Additionally, the confirmed presence of S. cohnii suggested that the culture was being contaminated by the supplier’s personnel. (Information in the public domain indicated that there is a strong association between the organism and humans.)

Figure 1. RiboPrint® patterns show the clear genetic distinction between Staphylococcus carnosus, the desired fermenting agent, and Staphylococcus cohnii and Staphylococcus saprophyticus, undesirable contaminants. The RiboPrinter® system became a valuable quality control tool for both the purchaser and supplier of the starter cultures.


RiboPrinter® system characterization gave both the manufacturer and the culture supplier the definitive microbial profile they needed to control the quality of their products and the process by which they were made. Quality of the meat products improved with changes made based on the RiboPrint® patterns and the culture supplier suddenly had access to a new, definitive way of analyzing the microbial profile of its cultures.

RiboPrinter® and RiboPrint™ are registered trademarks or trademarks of DuPont or its affiliates. Use for research and development, quality assurance and quality control testing under supervision of technically qualified persons. Not approved for clinical use. Please read the limitation of warranty and liability before use