Characterization of Achlya Infection on Giant Gourami (Osphronemus goramy) in Indonesia Based on Morphology and Molecular Method

Saprolegniasis on Gourami in Indonesia was not reported based on the morphological and molecular characterization of the causative fungus. This study purposed to characterize the fungi that caused saprolegniasis on Gourami in Java, Indonesia based on morphology and molecular methods. The morphological method included the characterization of fungal structure and clinical signs due to fungal infections in Gourami. The molecular methods included analyzing the fungal internal transcribed spacer (ITS) rDNA sequences and their phylogeny. Fungal DNA was extracted, amplified by PCR, quantified with electrophoresis, and sequenced by Sanger’s method. The sequence was compared with the GenBank nucleotide database by BLASTn, alignment with MUSCLE, and phylogeny with maximum likelihood and neighbor-joining by MEGA XI. In the results, isolates were identified as Achlya based on achlyoid spore release from sporangium with more than one row of spores. All isolates of Achlya spp. had monoecious thallus, multi-oospores and non-ornamented oogonia, mature or immature oospores. Achlya sp. isolates 1, 2, 3, 5, 6, 7, and 8 had subcentric oospore, diclinous antheridia, or diclinous and hypogynous antheridia. Achlya sp, isolate 4 had subcentric or centric oospore and diclinous antheridia. As clinical signs, the mycelium of Achlya spp. grew on the integument of fins, operculum, mouth, and the body of infected Gourami, with a reddish lesion and integument erosion around the mycelium. Molecularly Achlya spp. isolates 1, 2, 3, 5, 6, 7, and 8 were not identified with another Achlya that has species epithet name in the GenBank based on percent identity (<94), and phylogenetically the isolates were separately independent clusters. Achlya sp. isolate 4 was identified as Newbya oblongata (synonym of Achlya oblongata) based on percent identity (99,84) and phylogenetically clustered with Newbya oblongata LC149928.1. © 2024, Egyptian Society for the Development of Fisheries and Human Health. All rights reserved.