The Synonyms of Bacterial Strains
Microbial Solutions
Sunhee Hong

The Synonyms of Bacterial Strains

Our quest to obtain global accreditation inadvertently turns up a glitch in the scientific literature—a bacterium’s fraternal twin. MicroPhyles Case No. 6

“We passed, however one of the sample IDs we submitted was actually wrong, so we received our test result for that sample as incorrect.”

This was the internal email I received from a senior leader alerting us to the results of a routine quality assurance test intended to measure proficiency and competence at identifying microbes correctly. The underlying message: We had misnamed our Pseudomonas sample, a rookie mistake.

Say what??!!!

Charles River prides itself on its accurate identification of microbes, with a service process firmly compliant with current Good Manufacturing Practices. And the International Organization for Standardization (ISO) assures good quality systems are in place to ensure that laboratories are competent.

We rarely miss. It didn’t make sense that we would have mixed up our bacterial strains, a potentially serious error had this been an actual request from a client.

During all the head-scratching, I thought back to what had led up to this quality assurance test. With multiple branches being established abroad, it made sense for all our sites in the US and elsewhere to follow the same quality system. This led us to apply for accreditation from the ISO under its testing and calibration laboratories category. ISO, with its 162 members, is the world's largest developer of voluntary international standards, and facilitates world trade by providing common standards between nations.

As part of the accreditation process, we received three blind samples last year to process and identify in-house. One of the samples appeared to be Pseudomonas oleovorans—a Gram-negative bacteria found in oil-water emulsions used as lubricants and cooling agents in the cutting and grinding of materials. Even though I was confident of the result, the company providing the sample said it was actually Pseudomonas pseudoalcaligenes, a strain first isolated in swimming pools.

A bit of detective work on my part explained the discrepancy. An article I found from 20101 suggested that Pseudomonas pseudoalcaligenes was a later heterotypic synonym of Pseudomonas oleovorans. In other words, it had undergone a name change, but no one had caught up with the story, including the National Collection of Type Culture (NCTC), the repository that supplied the reference strains for our quality assurance test.

Yes, Pseudomonas pseudoalcaligenes was reclassified to Pseudomonas oleovorans and this name change has already been applied to our library as well as many other culture collections including American Type Culture Collection (ATCC) and Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSMZ).

We also provided an update to the company that administered the compliance test, and they amended their report to reflect a higher score—another fun day in the world of bacterial taxonomy.

Keeping taxonomic names current for the libraries and databases used for a microbial identification service is very important for providing accurate identifications. We must keep in mind that misidentification could be eventually harmful for the end-user and also detrimental to a company’s finances and reputation.

As I emphasized in my previous blog2, communicating with the appropriate organizations to share what we found is very important. Of course, we have also informed NCTC and are awaiting their review. They already expressed to us that they are grateful for our efforts and would review and make any necessary amendments to their catalogue entry.

  1. List of Changes in Taxonomic Opinion no. 12. Int. J. Syst. Evol. Microbiol., 2010, 60, 1482-1483 [SAHA (R.), SPRÖER (C.), BECK (B.) and BAGLEY (S.): Pseudomonas oleovorans subsp. lubricantis subsp. nov., and reclassification of Pseudomonas pseudoalcaligenes ATCC 17440T as later synonym of Pseudomonas oleovorans ATCC 8062T. Curr. Microbiol., 2010, 60, 294-300.
  2. Hong, Sunhee. Out of Line. Eureka blog. Mar 28, 2016. Available: