Identification of contaminants in a commercial/industrial product.

Overview

• A company suspected bacterial contamination in a commercial product and wanted to confirm contamination and identify the bacteria in order to determine the source and eliminate contamination.

• Samples of the product were tested with standard microbial culturing methods. This method had shown the presence of bacterial contamination, but did not identify the bacteria.

• The company had believed that the product could not support the growth of bacteria, and hoped that by identifying the bacteria, they could determine what compound was providing a substrate for bacterial growth.

Question

What microbe is contaminating the product? What environmental conditions or substrate are allowing the growth of bacteria in the product?
 

Analyses Requested:
           
            DGGE

Results:

• Samples were taken at different steps along production. DGGE analysis showed two distinct bands in each sample.

• The DNA sequences in each band were highly similar to sequences found in Halomonas sp. In nature, this bacteria is often found in salt and sodium lakes,  and can also grow under anaerobic conditions in the presence of nitrate.

Answer:

• The contaminating bacteteria were identified as being members of Halomonas species.

• The formula for the commercial product contained sodium nitrate, so it appeared that the Halomonas sp. was utilizing the product as substrate.