Pseudoalteromonas neustonica sp. nov., isolated from the sea surface microlayer of the Ross Sea (Antarctica), and emended description of the genus Pseudoalteromonas

Abstract

T grew optimally at 25 C and pH 7.5-8.5 in the presence of 1.0-3.0 % (w/v) sea salts. The major cellular fatty acids (>10 %) were C 16 : 1 !6c and/or C 16 : 1 !7c, C 16 : 0 , and C 18 : 1 !6c and/or C 18 : 1 !7c. The genomic DNA G+C content was 39.7 mol%. On the basis of the phylogenetic, genomic, chemotaxonomic and phenotypic data presented, we propose the name Pseudoalteromonas neustonica sp. nov. with the type strain PAMC 28425 T (=KCCM 43187 T =JCM 31286 T ).The genus Pseudoalteromonas was established by recombining 11 species of the genus Alteromonas and 1 species of the genus Pseudomonas into 12 species of the genus Pseudoalteromonas based on a wealth of phylogenetic analyses of nearly complete 16S rRNA gene sequences (Gauthier et al., 1995). The genus Pseudoalteromonas is classified in the family Alteromonadaceae, and members of this genus are Gramstain negative, aerobic, motile and have C 16 : 0 , C 16 : 1 !7c, C 17 : 1 !8c and C 18 : 1 !7c as major fatty acids and genomic G +C contents of 38-48 mol% (Bowman & McMeekin, 2005). At the time of writing, the genus Pseudoalteromonas comprises 41 species and 2 subspecies with validly published names (List of Prokaryotic Names with Standing in Nomenclature, http://www.bacterio.net/pseudoalteromonas.html; Park et al., 2016;Ying et al., 2016). Most species of the genus Pseudoalteromonas have been isolated from various marine habitats including seawater, sediment, marine invertebrates, algae and sea ice (Bowman & McMeekin, 2005). With cultivation-independent molecular techniques, pseudoalteromonads are also known as a ubiquitous marine group extending from the sea surface microlayer (SSM) to deep-sea sediment, and from equatorial to polar regions (Cui et al., 2008;Cunliffe & Murrell, 2009;Wietz et al., 2010).Here, we isolated a bacterial strain, which is the first representative of the genus Pseudoalteromonas isolated from Antarctic SSM to our knowledge, and performed a polyphasic taxonomic analysis to determine the taxonomic position of the strain.A SSM sample was taken using a customized SSM sampler employing a type of rotating drum (Harvey 1966) covered with polycarbonate from the Terra Nova Bay (75.29 S Abbreviations: ANI, average nucleotide identity; GGDC, genome-togenome distance calculation; SSM, sea surface microlayer.The GenBank/EMBL/DBBJ accession number for the 16S rRNA gene sequence and the draft genome sequence of strain PAMC 28425 T are KU716039 and BDDS01000000, respectively.Two supplementary tables and one supplementary figure are available with the online Supplementary Material.

Pseudoalteromonas rhizosphaerae sp. nov., a novel plant growth-promoting bacterium with potential use in phytoremediation

“…These features were very similar to the other species of the genus and matched the genus description [1]. Strain RA15 T also was able to grow on MA as other species described in the genus [1,4,7,8,12,44]. Contrarily, growth on MacConkey agar and cetrimide agar was not observed.…”

“…Furthermore, RA15 T was Voges-Proskauer positive and produced the media acidification from d-ribose, trehalose, starch and glycogen according to API 20Strep gallery results. These results showed some differences from other species of the genus Pseudoalteromonas regarding the assimilation of adipic acid and the production of acetoin (Voges-Proskauer positive) [7,8,42,43]. Finally, strain RA15 T was catalase-and oxidase-positive in line with other species in the genus [1].…”

“…It is currently shaped by 47 species [3] characterized by presenting Gram-stain-negative, motile, non-spore forming, aerobic, oxidase positive rods [4] requiring Na + ions for growth [5] whose type species is Pseudoalteromonas haloplanktis [1,4,6]. Hitherto, all species described into the genus Pseudoalteromonas were isolated from marine environments, mainly seamount [7], sea water [4,[8][9][10], tidal flat [11] and as hosts of marine organisms [4,[12][13][14].…”

“…Cells appeared single or in pairs under optical microscope. Although most species described in the genus Pseudoalteromonas are motile [1,4,7,8,12,[41][42][43], the absence of motility is not exclusive of strain RA15 T as this characteristic was already noted in other species such as Pseudoalteromonas gelatinilytica [44]. RA15 T cells formed cream-coloured (RAL 075 90 20), opaque, mucoid, viscous, convex, irregular colonies with an undulate margin and were 3.75 mm in size after 24 h on TSA 2.5 % NaCl (w/v) plates at 28 °C.…”

“…Esterase (C4), cysteine arylamidase, α-chymotrypsin and α-galactosidase activity were also identified, but those results was weak. The presence of some enzymes like β-glucosidase, cysteine arylamidase, α-chymotrypsin, α-galactosidase, pyrolidonyl arylamidase and leucine aminopeptidase makes strain RA15 T metabolically different from other species of the genus Pseudoalteromonas [7,8,42,43]. In addition, the API 20NE gallery showed that strain RA15 T reduced nitrates to nitrites and was able to assimilate d-glucose, l-arabinose, d-mannose, d-mannitol, N-acetyl-glucosamine, maltose, potassium gluconate, adipic acid and malic acid.…”