The influence of Janthinobacterium sp. strain SLB01 on the cell culture of primmorphs of the sponge Lubomirskia baicalensis

Sponges (phylum Porifera) are ancient, filtering, multicellular metazoans. Freshwater sponges (Demosponges, Lubomirskiidae) dominate the fauna of the littoral zone of Lake Baikal. Over the last years, there have been mass diseases and death of endemic sponges. Previously, the strain Janthinobacterium sp. SLB01 was isolated from the diseased sponge Lubomirskia baicalensis. The studies of the pathogenicity of the strain Janthinobacterium sp. SLB01 for Baikal sponges has not been carried out. Therefore we infected experimentally in vitro to determine its pathogenicity by the cell culture of the primmorphs with subsequent isolation, sequencing, and analysis of the genomes. The purpose of the study is to show that the strain Janthinobacterium sp. SLB01 isolated from the diseased sponge L. baicalensis is a pathogen for the cell culture of primmorphs. The bacteria from the infected samples of the primmorphs were isolated and identified as strain Janthinobacterium sp. PLB02. A comparative analysis of the genomes of the strains Janthinobacterium sp. SLB01 and Janthinobacterium sp. PLB02 showed that they are practically identical. The genomes of both strains contain genes vioABCDE violacein, flok formation, and strong biofilm, and the type VI secretion system (T6SS), as the primary virulence factor. The bacterial strains Janthinobacterium sp. based on a comparison of complete genomes showed similarity with strain Janthinobacterium lividum MTR. Isolated our strains of Janthinobacterium sp. are pathogens for cell cultures of primmorphs and L. baicalensis sponges. The results of the study will help to expand the understanding of microbial relationships in the development of disease and the death of Baikal sponges.