Novel species and expanded distribution of ellipsoidal multicellular magnetotactic prokaryotes

Abstract

Multicellular magnetotactic prokaryotes (MMPs) are a peculiar group of magnetotactic bacteria, each comprising approximately 10-100 cells of the same phylotype. Two morphotypes of MMP have been identified, including several species of globally distributed spherical mulberry-like MMPs (s-MMPs), and two species of ellipsoidal pineapple-like MMPs (e-MMPs) from China (Qingdao and Rongcheng cities). We recently collected e-MMPs from Mediterranean Sea sediments (Six-Fours-les-Plages) and Drummond Island, in the South China Sea. Phylogenetic analysis revealed that the MMPs from Six-Fours-les-Plages and the previously reported e-MMP Candidatus Magnetananas rongchenensis have 98.5% sequence identity and are the same species, while the MMPs from Drummond Island appear to be a novel species, having > 7.1% sequence divergence from the most closely related e-MMP, Candidatus Magnetananas tsingtaoensis. Identification of the novel species expands the distribution of e-MMPs to Tropical Zone. Comparison of nine physical and chemical parameters revealed that sand grain size and the content of inorganic nitrogen (nitrate, ammonium and nitrite) in the sediments from Rongcheng City and Six-Fours-les-Plages were similar, and lower than found for sediments from the other two sampling sites. The results of the study reveal broad diversity and wide distribution of e-MMPs.

Juxtaposed membranes underpin cellular adhesion and display unilateral cell division of multicellular magnetotactic prokaryotes

“…We collected MTB by racetrack magnetic enrichment and obtained five 16S rRNA gene sequences that potentially belonged to MMPs. One of them (SF‐1) was identical to the previously identified ellipsoidal MMPs collected from this site (Chen et al ., ), and the others shared higher than 90% identity with SF‐1. Using correlative FISH‐SEM analysis, we confirmed the authenticity of the ellipsoidal MMPs SF‐2 to SF‐5 and showed species‐dependent cell morphology and magnetosome arrangement in the MMPs (Fig.…”

“…Although the short axis dissection of ellipsoidal MMPs exhibits radial symmetry like sMMPs, but only the ellipsoidal MMP cells axisymmetrically assemble into several rows to form a pineapple‐like morphology. At present no unicellular stage has been observed for MMPs [(Keim et al ., , ; Abreu et al ., , ; Zhou et al ., ; Zhang et al ., ; Chen et al ., , ) and FISH in this study]. Our phylogenetic analysis, based on 16S rRNA gene sequences, revealed that the MMP cluster is located distantly to myxobacteria and other unicellular MTB (Fig.…”

“…This behaviour is referred to as escape motility or ping‐pong motion. In addition, illumination with blue, violet or UV light triggers the MMPs to swim away from the droplet edges opposite to the magnetotaxis direction, which is referred to as a photophobic response or is sometimes miscalled negative phototaxis (Shapiro et al ., ; Zhou et al ., , ; Zhang et al ., ; Chen et al ., , )…”

“…This type of MMPs has been observed worldwide (Rodgers et al ., ; Simmons and Edwards, ; Winklhofer et al ., ; Wenter et al ., ; Shapiro et al ., ; Zhou et al ., ; Zhang et al ., ). Besides the spherical MMPs (sMMPs), we have identified another morphotype, the ellipsoidal or pineapple‐like MMPs (eMMPs) in the Mediterranean Sea (Lefèvre et al ., ; Chen et al ., ), the China Sea and the Pacific Ocean (Zhou et al ., ; Chen et al ., ; Du et al ., ; Dong et al ., ; Teng et al ., ). Approximately 60 cells aggregate into four to six interlacing circles to form a ~5–10 μM ellipsoidal entity.…”

Ultrastructure of ellipsoidal magnetotactic multicellular prokaryotes depicts their complex assemblage and cellular polarity in the context of magnetotaxis

“…M. multicellularis showed that the greigite and magnetite syntheses have common ancestry and that the magnetosome genes mam ‐ A‐B‐E‐K‐M‐O‐P‐Q and ‐ T are conserved in both processes (Abreu et al ., ). eMMPs are composed of approximately 40 to 86 cells organized in a 10 x 8 μm assemblage (Zhou et al ., ; Chen et al ., ; Chen et al ., ) containing thousands of magnetosomes organized in chains. Fluorescent lipid staining showed that an outer layer (Zhou et al ., ) envelops the whole organism.…”