Two Genera of Magnetococci with Bean-like Morphology from Intertidal Sediments of the Yellow Sea, China

Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
Applied and Environmental Microbiology (Impact Factor: 3.67). 06/2012; 78(16):5606-11. DOI: 10.1128/AEM.00081-12
Source: PubMed


Magnetotactic bacteria have the unique capacity of being able to swim along geomagnetic field lines. They are Gram-negative
bacteria with diverse morphologies and variable phylogenetic relatedness. Here, we describe a group of uncultivated marine
magnetococci collected from intertidal sediments of Huiquan Bay in the Yellow Sea. They were coccoid-ovoid in morphology,
with an average size of 2.8 ± 0.3 μm by 2.0 ± 0.2 μm. Differential interference contrast microscopy, fluorescence microscopy,
and transmission electron microscopy revealed that each cell was apparently composed of two hemispheres. The cells synthesized
iron oxide-type magnetosomes that clustered on one side of the cell at the interface between the two hemispheres. In some
cells two chains of magnetosomes were observed across the interface. Each cell had two bundles of flagella enveloped in a
sheath and displayed north-seeking helical motion. Two 16S rRNA gene sequences having 91.8% identity were obtained, and their
authenticity was confirmed by fluorescence in situ hybridization. Phylogenetic analysis revealed that the magnetococci are affiliated with the Alphaproteobacteria and are most closely related to two uncultured magnetococci with sequence identities of 92.7% and 92.4%, respectively. Because
they display a >7% sequence divergence to all bacteria reported, the bean-like magnetococci may represent two novel genera.

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    • "Hence, isolation and cultivation of marine Actinobacteria might result in discovery of novel MNPs to combat drug-resistant pathogens and new diseases (Xiong et al. 2012). The Yellow Sea, one of the 64 so-called large marine ecosystems in the world (Liu et al. 2013), is a marginal sea of the Pacific Ocean located between mainland China and the Korean Peninsula, which has significant diversity of microorganism (Xiong and Wang 2012a, b; Zhang et al. 2012; Zhou et al. 2012; Liu et al. 2013). However, there are only a few investigations on marine Actinobacteria and theirs natural products in the environment of Yellow Sea (Xiong and Wang 2012a, b). "
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    • "Members of MTB occupy a wide array of ecosystems, including lakes, rivers, ponds, estuaries and salt marshes, lagoons, mangrove swamps, intertidal zones, deep-sea sediments, soils, and even some extreme environments (Fassbinder et al., 1990; Petermann and Bleil, 1993; Flies et al., 2005a; Simmons et al., 2007; Pan et al., 2008; Jogler and Schüler, 2009; Jogler et al., 2009; Wenter et al., 2009; Sobrinho et al., 2011; Lin et al., 2012c; 2013; Martins et al., 2012; Zhang et al., 2012; 2013; Zhou et al., 2012; 2013; Bazylinski and Lefèvre, 2013). So far MTB have been globally detected from Asia, Europe, North and South America, Africa, Australia, and Antarctica (Fig. 2). "
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    • "FISH was carried out according to the protocol reported by Simmons and Edwards (2007). Cells were magnetically collected and treated as previously described (Zhang et al., 2012), and the hybridized samples were analyzed using a BX51 microscope equipped with epifluorescence and a camera system DP71 (Olympus, Tokyo, Japan). "
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