Chlamydial seasonal dynamics and isolation of ‘Candidatus Neptunochlamydia vexilliferae’ from a Tyrrhenian coastal lake

Abstract

The Chlamydiae are a phylum of obligate intracellular bacteria comprising important human and animal pathogens, yet their occurrence in the environment, their phylogenetic diversity and their host range has been largely underestimated. We investigated the seasonality of environmental chlamydiae in a Tyrrhenian coastal lake. By catalysed reporter deposition fluorescence in situ hybridization, we quantified the small planktonic cells and detected a peak in the abundance of environmental chlamydiae in early autumn with up to 5.9 × 10(4) cells ml(-1) . Super-resolution microscopy improved the visualization and quantification of these bacteria and enabled the detection of pleomorphic chlamydial cells in their protist host directly in an environmental sample. To isolate environmental chlamydiae together with their host, we applied a high-throughput limited dilution approach and successfully recovered a Vexillifera sp., strain harbouring chlamydiae (93% 16S rRNA sequence identity to Simkania negevensis), tentatively named 'Candidatus Neptunochlamydia vexilliferae'. Transmission electron microscopy in combination with fluorescence in situ hybridization was used to prove the intracellular location of these bacteria representing the first strain of marine chlamydiae stably maintained alongside with their host in a laboratory culture. Taken together, this study contributes to a better understanding of the distribution and diversity of environmental chlamydiae in previously neglected marine environments.

The cooling tower water microbiota: Seasonal dynamics and co-occurrence of bacterial and protist phylotypes

“…This indicates that in a natural setting, bacterial symbionts are more promiscuous and thrive in a wide range of different protists. Among the taxa included in the networks, there are several protists recognized previously as hosts for intracellular bacteria: The amoeba Vexillifera is a known host of the environmental chlamydia ‘ Candidatus Neptunochlamydia vexilliferae’ (Pizzetti et al., 2016). Hartmannella (Vermamoeba) is the natural host of an intranuclear symbiont, ‘ Candidatus Nucleicultrix amoebiphila‘ and the environmental chlamydia Rubidus massiliensis (Bou Khalil et al., 2016; Horn, 2008; Schulz et al., 2014).…”

Unexpected genomic features in widespread intracellular bacteria: evidence for motility of marine chlamydiae

“…Chlamydiae have also been identified in a number of marine animals, including fish in which they have been associated with the gill disease epitheliocystis (Pawlikowska-Warych and Deptuła, 2016; Draghi et al , 2010; Stride et al , 2013; Karlsen et al , 2008; Mitchell et al , 2010; Fehr et al , 2013; Nylund et al , 2015; Steigen et al , 2015). Moreover, metagenomics and amplicon sequencing data indicates the existence of a vast, yet unexplored diversity of divergent chlamydiae, primarily in marine environments (Lagkouvardos et al , 2014; Pizzetti et al , 2012; Bou Khalil et al , 2016; Vanthournout and Hendrickx, 2015; Pizzetti et al , 2015). However, owing to their obligate intracellular lifestyle our knowledge about chlamydiae is based on a limited number of representatives, originating exclusively from non-marine environments.…”

Morphological and molecular investigation of Vexillifera cf. armata Page, 1979 (Amoebozoa: Dactylopodida) isolated from the Pacific Ocean

“…comprised exclusively marine and brackish water species. The studied strain was in a clade comprising V. tasmaniana, V. abyssalis and two unnamed strains S2M1 and K9; the former isolated from the turbot (Scophthalmus maximus), while the latter, from the marine lagoon at the eastern Italian coast (Dyková, Kostka, 2013;Pizzetti et al, 2016). The latter strain was the closest relative to VO16.21I5.1 (support 1.0/100).…”

“…The genuine members of Vexillifera always form a clade distinct from Pseudoparamoeba (Dyková et al, 2011;Kudryavtsev et al, 2018). Later on, a strain of Vexillifera was isolated and studied from the marine habitat in the Mediterranean Sea, that resembled V. armata possessing similar trichocyst-like bodies, but had a different cell coat (Pizzetti et al, 2016). The purpose of this paper is to report an isolation and a molecular investigation of another strain of Vexillifera that is morphologically almost identical to V. armata Page, 1979.…”