Risk assessment of Chryseobacterium nematophagum

The bacterium Chryseobacterium nematophagum belongs to the Weeksellaceae family and is known as a nematode-killing microorganism. The golden color of C. nematophagum colonies gives the entire genus Chryseobacterium its name ("golden bacteria"). These gram-negative, aerobic bacteria multiply optimally at 30°C; no growth occurs at 37°C. So far, two strains of C. nematophagum (JUb129 and JUb275) were isolated from rotting fruit contaminated with the bacterivorous nematode Caenorhabditis briggsae. Later, it was found that bacteria from these two strains, along with C. briggsae can also infect and kill other parasitic nematodes, including those of veterinary importance. The C. nematophagum The enzymes chitinase and collagenase encoded in the genome play an important role. Furthermore, several other genes for potential virulence factors, including some toxin genes, have been identified in the bacterium's genome. Due to its specific pathogenicity, C. nematophagum is considered a potential biological control agent against parasitic nematodes. Reports of C. infections have been reported. nematophagum There are currently no data available for vertebrates. Technical Rules for Biological Agents 466 "Classification of Prokaryotes (Bacteria and Archaea)" currently list 107 Chryseobacterium species, five of which are classified in Risk Group 2 (all other species are classified in Risk Group 1). C. nematophagum is not yet listed in the TRBA 466. An analysis of the 16S rRNA sequences of C. nematophagum showed that this species is most closely related to Chryseobacteria of the Risk group 1 is related.

According to Section 5 Paragraph 1 GenTSV in conjunction with the criteria in Annex 1 GenTSV, the ZKBS C. nematophagum as a donor and recipient organism for genetic engineering work in risk group 1. C. nematophagum infects and specifically kills bactericidal nematodes. Currently, there is no evidence of infection in other animal species, including humans. Colonization of warm-blooded vertebrates is also unlikely, since C. nematophagum does not grow at temperatures around 37°C. It should be noted that in genetic engineering work where nucleic acid segments of C. nematophagum , which code for virulence factors (e.g. toxins), are transferred to a recipient organism of risk group 1, the resulting GMO may be upgraded to risk group 2.

The ZKBS statement can be found at File number 45241.0219 can be retrieved.