engleski

Bacterial isolates from crayfish cuticule as potential source of anti-oomycete compounds

Microorganism Aphanomyces astaci (Schikora, 1906) (Oomycetes) causes the crayfish plague, a lethal disease responsible for rapid declines of many populations of native European decapod crayfish species. During the infection process, A. astaci mycelium is invading the host through the cuticle and then spreads through the whole body of the crayfish. However, at the surface of crayfish cuticle it firstly comes in contact with commensal bacteria. The important role of commensal bacteria in host protection from pathogens has been shown on other models, but the interaction of A. astaci with epibiontic microbial communities is completely unexplored. The aim of this study was to explore the potential of bacterial isolates originating from crayfish cuticle to inhibit the growth of A. astaci mycelium. We took swabs of cuticle biofilm from five individuals of narrow-clawed 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 mixed cultures. We identified the isolates by MALDI–TOF mass spectrometry and 16S rRNA gene sequencing and tested their potential to inhibit A. astaci. Dominant bacterial genera among isolates were Pseudomonas and Acinetobacter. Out of 46 isolates from narrow-clayed crayfish, 13 exhibited great potential for A. astaci inhibition (28 %), while out of 44 isolates from signal crayfish, only 7 showed great inhibition potential (16 %). Most of the potent inhibitors belonged to genus Pseudomonas, for which inhibition of fish pathogenic oomycete from genus Saprolegnia was previously shown. In conclusion, we have characterized cultivable crayfish-associated bacterial communities and shown their potential as a source of anti-oomycete compounds.

Aphanomyces astaci, bacterial isolates, crayfish plague, Oomycetes, plate inhibition assay

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