engleski

Can bacteria from crayfish surface protect their host from invasive oomycete Aphanomyces astaci, causative agent of crayfish plague?

The invasive oomycete Aphanomyces astaci (Schikora, 1906) is listed among the 100 worst invasive alien species in the world. It causes the crayfish plague, a lethal disease responsible for rapid declines of many native European crayfish populations. It came to Europe with the North American invasive crayfish that are mostly resistant to the disease and act as A. astaci carriers. During the infection process, A. astaci hyphae are penetrating through the crayfish cuticle. We hypothesised that bacteria naturally present on the cuticle can help in the protection of the host from A. astaci. To test this, we took swabs of cuticle biofilm from five individuals of narrowclawed crayfish, Astacus leptodactylus Eschscholtz, 1823 and five individuals of signal crayfish, Pacifastacus leniusculus (Dana, 1852), inoculated them on PG1 agar, and subsequently, isolated morphologically different individual colonies from the mixed cultures. We identified the isolates by MALDI–TOF mass spectrometry and 16S rRNA gene sequencing and tested their potential to inhibit the growth of A. astaci mycelium in vitro. Out of 40 isolates from narrow-clawed crayfish, 15 exhibited great potential for A. astaci inhibition (37.5%), while out of 31 isolates from signal crayfish, only four showed great inhibition potential (12.9%). Most of the potent inhibitors belonged to the genus Pseudomonas. In conclusion, we have characterised cultivable bacterial communities from the crayfish cuticle for the first time and have shown their potential as a source of anti-oomycete compounds. Chemical basis of A. astaci inhibition by pseudomonads should be studied in the future.

plate inhibition assay ; biocontrol ; crayfish plague ; epibionts

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