Genome Analysis of the Janthinobacterium sp. Strain SLB01 from the Diseased Sponge of the Lubomirskia baicalensis.

Sergei I Belikov,Ivan S Petrushin,Lubov I Chernogor

doi:10.3390/cimb43030156

Abstract

The strain Janthinobacterium sp. SLB01 was isolated from the diseased freshwater sponge Lubomirskia baicalensis (Pallas, 1776) and the draft genome was published previously. The aim of this work is to analyze the genome of the Janthinobacterium sp. SLB01 to search for pathogenicity factors for Baikal sponges. We performed genomic analysis to determine virulence factors, comparing the genome of the strain SLB01 with genomes of other related J. lividum strains from the environment. The strain Janthinobacterium sp. SLB01 contained genes encoding violacein, alpha-amylases, phospholipases, chitinases, collagenases, hemolysin, and a type VI secretion system. In addition, the presence of conservative clusters of genes for the biosynthesis of secondary metabolites of tropodithietic acid and marinocine was found. We present genes for antibiotic resistance, including five genes encoding various lactamases and eight genes for penicillin-binding proteins, which are conserved in all analyzed strains. Major differences were found between the Janthinobacterium sp. SLB01 and J. lividum strains in the spectra of genes for glycosyltransferases and glycoside hydrolases, serine hydrolases, and trypsin-like peptidase, as well as some TonB-dependent siderophore receptors. Thus, the study of the analysis of the genome of the strain SLB01 allows us to conclude that the strain may be one of the pathogens of freshwater sponges.

Highlights

Sponges (Porifera) are sessile metazoans, filter-feeding invertebrates that grow in many different ecological niches around the world and contain a variety of symbiotic microorganisms, including viruses, bacteria, microalgae, fungi, and protozoa [1,2]
The bacteria isolated from the diseased sponge L. baicalensis, which we further named Janthinobacterium sp. strain SLB01, was rod-shaped, Gram-negative, motile, aerobic bacteria; a purple pigment violacein appeared on the second day (Figure 1A)
We found that the genome of the Janthinobacterium sp. strain SLB01 encodes all three majoAr pnraolytesiinsssohfotwheedTAtThaptastthrwaiany Jiannathsininogblaectcelruisutmer,slpis.teSdLBin01TaibsleclSo1s,ewstittho stehveerJa. llividum MprToRteiannsdthEaitf2arsetrsaeicnrsetiesdolbaytetdhereTsaptepcattihvwelayyfraonmd mCaajyónbedaeslsMocaiaipteod, wChitihlev[i3ru4l]e, nacned. fItrom the eisnvkinroownmn tehnattatlhoelitgwoitnr-oaprghiincinweattrearnpslooncadtiionnG(TeArmT)asnyyst[e3m5],.loBcoatthedofinththeseecsyttroapilnassmwiecre closemste(mTbarbalneeSs1o2f) mtoatnhye bstarcatienriJaa,natrhcihnaoebaa,ctaenridumchslopr.oSpLlaBs0ts1, pwrhovicihdews aasctiisvoelattreadnsfprormt odfiseased sepxopnogrte-fso, lbduedt tphreotpeainths oagcreonsiscitthye oinfntehrelisptridaimnsemJabnrtahnineo. bTahcteerTiautmsyMsteTmR iasnrdeqEuIiFre2dinforanimals wcoalsonniozat tdioens,cbriibofiedlm

Summary

Introduction

Sponges (Porifera) are sessile metazoans, filter-feeding invertebrates that grow in many different ecological niches around the world and contain a variety of symbiotic microorganisms, including viruses, bacteria, microalgae, fungi, and protozoa [1,2]. The study of diseases of sponges is difficult because they are the host organisms of a wide variety of permanent, symbiotic microbial communities that are commensals [6]. In most cases, it was unclear whether the bacteria are the primary or secondary pathogens in the disease process. A number of studies have shown the loss of the main symbionts that are characteristic of healthy sponges with the appearance of a high abundance of uncharacteristic pathogens [8–10]. The large number and low relative abundance of bacteria in newly colonized tissues made it difficult to find real pathogens of sponges; etiological agents were found only in a few cases [9,11,12]. The strain was identified by NGS sequencing and complete genome analysis as the gamma Proteobacterium Pseudoalteromonas agarivorans NW4327 [13,14]

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