by Jonathan Latham, PhD and Allison Wilson, PhD
Genetically engineered (GE) bacteria have been found in riboflavin vitamin supplements intended for animal feed use according to newly published EU tests.
Contamination of food grade or animal feed supplements with GE bacteria is illegal in the European Union. In 2014, however, a German enforcement laboratory alerted EU officials to illegal GE bacterial contamination of a riboflavin supplement intended for animal feed. Further tests showed that the illegal contaminating strain was not among those the manufacturer claimed to be using.
The findings, just published in the journal Food Chemistry, were made by regulators from Germany and Italy who were sampling Chinese imports (Paracchini et al., 2017).
Riboflavin (vitamin B2) is an essential vitamin of vertebrate organisms. It is commonly used as a food additive for humans and animals. Until quite recently, all riboflavin supplements were chemically synthesised. However, riboflavin is now frequently produced by commercial fermentation using overproducing strains of GE bacteria.
According to EU biosafety regulations, no GMO bacterial strain, nor any DNA, is allowed to be present in commercial supplements. However, the contaminated sample of riboflavin contained viable strains of the genetically modified organism Bacillus subtilis. The researchers cultured and tested the contaminating bacterium and subsequent DNA sequencing showed it to be a production strain.
Further testing showed it to contain genomic DNA conferring resistance to the antibiotic chloramphenicol. In addition, the strain contained DNA extrachromosomal plasmids with other antibiotic resistance genes. These conferred resistance to the antibiotics, ampicillin, kanamycin, bleomycin, tetracycline, and erythromycin.
Correspondence between German diplomats, Chinese authorities, and the company, subsequently established that these antibiotic resistance genes constituted key differences between the strains the company claimed to be using and what was detected in Germany. Only the erythromycin and chloramphenicol resistance genes were acknowledged by the producer. Whether the altered strains had been used intentionally or were inadvertent contaminants is still not clear.
In 2015 a French testing laboratory found one riboflavin sample also contaminated with what is likely to be an identical bacterial strain, again from China (Barbau-Piednoir et al., 2015).
According to Janet Cotter of the consultancy Logos Environmental, European Food Safety Authority regulations state that antibiotic resistance genes “should be restricted to field trial purposes and should not be present in GM plants to be placed on the market” to prevent them entering the food chain as these antibiotic resistance genes presumably have. “This incident is the latest in a series of GMO escapes. It highlights the need for a database of detection methodologies for all GMOs used, both in contained use and at the field trial stage, so any escapees can at least be detected without facing the serious analytical challenges identification of this GMO contaminant posed.”
The publication documenting the tests also highlighted various altered properties of the detected Bacillus subtilis strain, including reduced fidelity of its protein translation system which might lead it to produce novel proteins.
Barbau-piednoir, E. Sigrid C. J. De Keersmaecker, Maud Delvoye, Céline Gau, Patrick Philipp and Nancy H. Roosens (2015) Use of next generation sequencing data to develop a qPCR method for specific detection of EU-unauthorized genetically modified Bacillus subtilis overproducing riboflavin. BMC Biotechnology 2015 15:103 DOI: 10.1186/s12896-015-0216-y
Paracchini, V., Petrillo, M., Reiting, R., Angers-Loustau, A., Wahler, D., Stolz, A., … & Pecoraro, S. (2017). Molecular characterization of an unauthorized genetically modified Bacillus subtilis production strain identified in a vitamin B 2 feed additive. Food Chemistry, 230, 681-689.