Cold-Active Shewanella glacialimarina TZS-4T nov. Features a Temperature-Dependent Fatty Acid Profile and Putative Sialic Acid Metabolism

Abstract

Species of genus Shewanella are among the most frequently identified psychrotrophic bacteria. Here, we have studied the cellular properties, growth dynamics, and stress conditions of cold-active Shewanella strain #4, which was previously isolated from Baltic Sea ice. The cells are rod-shaped of ~2μm in length and 0.5μm in diameter, and they grow between 0 and 25°C, with an optimum at 15°C. The bacterium grows at a wide range of conditions, including 0.5–5.5% w/v NaCl (optimum 0.5–2% w/v NaCl), pH 5.5–10 (optimum pH 7.0), and up to 1mM hydrogen peroxide. In keeping with its adaptation to cold habitats, some polyunsaturated fatty acids, such as stearidonic acid (18:4n-3), eicosatetraenoic acid (20:4n-3), and eicosapentaenoic acid (20:5n-3), are produced at a higher level at low temperature. The genome is 4,456kb in size and has a GC content of 41.12%. Uniquely, strain #4 possesses genes for sialic acid metabolism and utilizes N-acetyl neuraminic acid as a carbon source. Interestingly, it also encodes for cytochrome c3 genes, which are known to facilitate environmental adaptation, including elevated temperatures and exposure to UV radiation. Phylogenetic analysis based on a consensus sequence of the seven 16S rRNA genes indicated that strain #4 belongs to genus Shewanella, closely associated with Shewanella aestuarii with a ~97% similarity, but with a low DNA–DNA hybridization (DDH) level of ~21%. However, average nucleotide identity (ANI) analysis defines strain #4 as a separate Shewanella species (ANI score=76). Further phylogenetic analysis based on the 92 most conserved genes places Shewanella strain #4 into a distinct phylogenetic clade with other cold-active marine Shewanella species. Considering the phylogenetic, phenotypic, and molecular characterization, we conclude that Shewanella strain #4 is a novel species and name it Shewanella glacialimarina sp. nov. TZS-4T, where glacialimarina means sea ice. Consequently, S. glacialimarina TZS-4T constitutes a promising model for studying transcriptional and translational regulation of cold-active metabolism.

Bacteriophage Infection of the Marine Bacterium Shewanella glacialimarina Induces Dynamic Changes in tRNA Modifications

“…The host cells displayed a rod-shaped morphology, as previously described by Qasim et al [ 17 ]. In addition, a fraction of the cells expressed a single polar flagellum ( Figure 2 A).…”

“…Moreover, this study was carried out with undefined Zobell growth media based on aged Baltic Sea water [ 18 , 26 ]. We have previously shown that S. glacialimarina grows well in the defined 25% rMB [ 17 ], so we set out to recharacterize the infection characteristics in this new growth medium. First, we conducted infection cycle studies using an MOI ranging from 0.2 to 10 ( Supplementary Figure S1 ).…”

“…Cultivation of the host bacterium, Shewanella glacialimarina TZS-4 T (CP041216.1), was conducted as previously described by Qasim et al [ 17 ]. Strain TZS-4 T was grown on 25% rich Marine Broth (rMB) agar plates over two nights at 15 °C until colonies appeared.…”

“…with 2.5% ( v / v ) glutaraldehyde (Sigma) at 4 °C for 20 h, harvested (3200 g, 5 min, 4 °C), washed with 10 mL of PBS, and finally resuspended in 5 mL of PBS. The final samples for microscopy were prepared as previously described [ 17 ] and analyzed using a FEI Quanta 250 Field Emission Gun (FEG) Scanning Electron Microscope.…”

Shewanella oncorhynchi sp. nov., a novel member of the genus Shewanella, isolated from Rainbow Trout (Oncorhynchus mykiss)

“…S-1 T was cultured routinely in TSA medium at 25 °C. All phenotypic tests were performed twice at different times on freshly prepared medium using standard methods as described previously [6,[34][35][36][37][38]. The Gram-staining was performed using a Gram-Stain kit (bioMérieux).…”