Many marine sponges, hereafter termed high-microbial-abundance (HMA) sponges, harbor large and complex microbial consortia, including bacteria and archaea, within their mesohyl matrices. To investigate vertical microbial transmission as a strategy to maintain these complex associations, an extensive phylogenetic analysis was carried out with the 16S rRNA gene sequences of reproductive (n ‫؍‬ 136) and adult (n ‫؍‬ 88) material from five different Caribbean species, as well as all published 16S rRNA gene sequences from sponge offspring (n ‫؍‬ 116). The overall microbial diversity, including members of at least 13 bacterial phyla and one archaeal phylum, in sponge reproductive stages is high. In total, 28 vertical-transmission clusters, defined as clusters of phylotypes that are found both in adult sponges and their offspring, were identified. They are distributed among at least 10 bacterial phyla and one archaeal phylum, demonstrating that the complex adult microbial community is collectively transmitted through reproductive stages. Indications of host-species specificity and cospeciation were not observed. Mechanistic insights were provided using a combined electron microscopy and fluorescence in situ hybridization analysis, and an indirect mechanism of vertical transmission via nurse cells is proposed for the oviparous sponge Ectyoplasia ferox. Based on these phylogenetic and mechanistic results, we suggest the following symbiont transmission model: entire microbial consortia are vertically transmitted in sponges. While vertical transmission is clearly present, additional environmental transfer between adult individuals of the same and even different species might obscure possible signals of cospeciation. We propose that associations of HMA sponges with highly sponge-specific microbial communities are maintained by this combination of vertical and horizontal symbiont transmission.Sponges (phylum Porifera) are evolutionarily ancient Metazoa whose origin dates back about 600 million years to the Precambrian (26). With 7,000 formally described species and an estimated 15,000 extant species, sponges are among the most diverse marine invertebrate groups and are important components of all aquatic habitats, including freshwater environments, tropical reefs, and even the deep sea (19). Despite an enormous range of shapes, colors, and sizes, all sponges possess a relatively simple body plan which is adapted to a filter-feeding lifestyle (4). Large volumes of seawater are pumped through canals embedded in an extracellular matrix (55), termed the mesohyl, and microorganisms and small unicellular eukaryotes are taken up from the seawater with high efficiency, leaving the expelled water essentially sterile (37, 54).Numerous sponges live in permanent and close associations with microorganisms, and many of them host phylogenetically diverse populations of microbes (15,17,49). These microorganisms are located mainly extracellularly in the sponge mesohyl in high concentrations, contributing up to 40% of the sponge's biomass and...

The aim of this study was to examine sponge orange band (SOB) disease affecting the prominent Caribbean sponge Xestospongia muta. Scanning and transmission electron microscopy revealed that SOB is accompanied by the massive destruction of the pinacoderm. Chlorophyll a content and the main secondary metabolites, tetrahydrofurans, characteristic of X. muta, were significantly lower in bleached than in healthy tissues. Denaturing gradient gel electrophoresis using cyanobacteria-specific 16S rRNA gene primers revealed a distinct shift from the Synechococcus/Prochlorococcus clade of sponge symbionts towards several clades of unspecific cyanobacteria, including lineages associated with coral disease (i.e. Leptolyngbya sp.). Underwater infection experiments were conducted by transplanting bleached cores into healthy individuals, but revealed no signs of SOB development. This study provided no evidence for the involvement of a specific microbial pathogen as an etiologic agent of disease; hence, the cause of SOB disease in X. muta remains unidentified.

We report on a novel sponge disease, hereafter termed 'sponge white patch' (SWP), affecting the Caribbean sponge species Amphimedon compressa. SWP is characterized by distinctive white patches of variable size that are found irregularly on the branches of diseased sponges. Nearly 20% of the population of A. compressa at Dry Rocks Reef, Florida, USA, showed symptoms of SWP at the time of investigation

Thirty-three Yersinia strains previously characterized by the French Yersinia National Reference Laboratory (YNRL) and isolated from humans and animals were suspected to belong to six novel species by a recently described core genome multilocus sequence typing scheme. These strains and five additional strains from the YNRL were characterized using a polyphasic taxonomic approach including a phylogenetic analysis based on 500 core genes, determination of average nucleotide identity (ANI), determination of DNA G+C content and identification of phenotypic features. Phylogenetic analysis confirmed that the 38 studied strains formed six well-demarcated clades. ANI values between these clades and their closest relatives were <94.7 % and ANI values within each putative novel species were >97.5 %. Distinctive biochemical characteristics were identified in five out of the six novel species. All of these data demonstrated that the 38 strains belong to six novel species of the genus Yersinia : Yersinia artesiana sp. nov., type strain IP42281T (=CIP 111845T=DSM 110725T); Yersinia proxima sp. nov., type strain IP37424T (=CIP 111847T=DSM 110727T); Yersinia alsatica sp. nov., type strain IP38850T (=CIP 111848T=DSM 110726T); Yersinia vastinensis sp. nov., type strain IP38594T (=CIP 111844T=DSM 110738T); Yersinia thracica sp. nov., type strain IP34646T (=CIP 111842T=DSM 110736T); and Yersinia occitanica sp. nov., type strain IP35638T (=CIP 111843T=DSM 110739T).

Background Leptospirosis is a widespread zoonosis with global impact, particularly among vulnerable populations in resource-poor settings in tropical countries. Rodents have been considered to be the main reservoir of the disease; however, a wide variety of mammals can act as hosts as well. Here we examine the genetic diversity of Leptospira strains from biological samples of patients and animals in French Polynesia (FP) from 2011 to 2019. Methodology/Principal findings From 2011 to 2019, we have collected 444 blood samples from patients diagnosed as having leptospirosis. The limited volume of clinical material and low amount of leptospiral DNA in blood samples led us to develop a nested PCR targeting the secY locus that enabled us to amplify and sequence 244 samples (55%). In addition, 20 Leptospira strains recovered from the blood of patients from 2002 to 2011 were sequenced and fully characterized at the serogroup level and used as reference strains for the association of different phylogenetic branches with respective serogroups. The secY sequences were compared with publicly available sequences from patients and animal reservoirs in FP (n = 79). We identified rats as the main source of infection for L. borgpetersenii serogroup Ballum and L. interrogans serogroup Icterohaemorrhagiae, dogs as the main source of infection for L. interrogans serogroup Australis, and farm pigs as the main source of infection for L. interrogans serogroups Pomona or Canicola. L. interrogans was associated with the most severe infections with 10 and 5 fatal cases due to serogroups Icterohaemorrhagiae and Australis, respectively. Mortality was significantly associated with older age (p-value < 0.001). Conclusions/Significance We described the population dynamics of leptospires circulating among patients in FP, including two patients who were reinfected with unrelated Leptospira genotypes, and PLOS NEGLECTED TROPICAL DISEASES

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