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A Gram-staining-negative, aerobic, non-motile and coccoid, ovoid or rod-shaped bacterial strain, designated as JBTF-M21T, was isolated from a tidal flat sediment on the Yellow Sea, Republic of Korea. The neighbour-joining phylogenetic tree based on 16S rRNA gene sequences indicated that JBTF-M21T fell within the clade comprising the type strains of species of the genus Erythrobacter . JBTF-M21T exhibited 16S rRNA gene sequence similarities of 97.0–98.4 % to the type strains of Erythrobacter longus , Erythrobacter aquimaris , Erythrobacter nanhaisediminis , Erythrobacter vulgaris , Erythrobacter seohaensis , Erythrobacter litoralis and Erythrobacter citreus and 93.7–96.6 % to the type strains of the other species of the genus Erythrobacter . The ANI and dDDH values between JBTF-M21T and the type strains of E. longus , E. nanhaisediminis , E. seohaensis and E. litoralis were 70.83–72.93 % and 18.0–18.8 %, respectively. Mean DNA–DNA relatedness values between JBTF-M21T and the type strains of E. aquimaris , E. vulgaris and E. citreus were 12–24 %. The DNA G+C content of JBTF-M21T was 57.0 mol%. JBTF-M21T contained Q-10 as the predominant ubiquinone and C18 : 1ω7c and C17 : 1ω6c as the major fatty acids. The major polar lipids ofJBTF-M21T were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and sphingoglycolipid. Distinguishing phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that JBTF-M21T is separated from species of the genus Erythrobacter with validly published names. On the basis of the data presented, strain JBTF-M21T is considered to represent a novel species of the genus Erythrobacter , for which the name Erythrobacter insulae sp. nov. is proposed. The type strain is JBTF-M21T (=KACC 19864T=NBRC 113584T).

The synthesis of bioplastic from marine microbes has a great attendance in the realm of biotechnological applications for sustainable eco-management. This study aims to isolate novel strains of poly-&beta, hydroxybutyrate (PHB)-producing bacteria from the mangrove rhizosphere, Red Sea, Saudi Arabia, and to characterize the extracted polymer. The efficient marine bacterial isolates were identified by the phylogenetic analysis of the 16S rRNA genes as Tamlana crocina, Bacillus aquimaris, Erythrobacter aquimaris, and Halomonas halophila. The optimization of PHB accumulation by E. aquimaris was achieved at 120 h, pH 8.0, 35 &deg, C, and 2% NaCl, using glucose and peptone as the best carbon and nitrogen sources at a C:N ratio of 9.2:1. The characterization of the extracted biopolymer by Fourier-transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), and Gas chromatography-mass spectrometry (GC-MS) proves the presence of hydroxyl, methyl, methylene, methine, and ester carbonyl groups, as well as derivative products of butanoic acid, that confirmed the structure of the polymer as PHB. This is the first report on E. aquimaris as a PHB producer, which promoted the hypothesis that marine rhizospheric bacteria were a new area of research for the production of biopolymers of commercial value.

Objectives: In silico analysis identified a metallo-b-lactamase (MBL) in Erythrobacter litoralis HTCC2594, sharing 55% amino acid identity with NDM-1. The aim of this work was to characterize the chromosomally encoded MBLs from several Erythrobacter spp. that may represent potential reservoirs of acquired MBLs. Methods: Erythrobacter citreus, Erythrobacter flavus, Erythrobacter longus, Erythrobacter aquimaris and Erythrobacter vulgaris were from the Pasteur Institute collection, France. DNA was extracted and used for shotgun cloning, and b-lactamases were expressed in Escherichia coli. MICs for resulting E. coli recombinant strains were determined by Etest. The deduced amino acid sequences were analysed and compared with BLASTP. Enzymatic activity of bacterial extracts from recombinant E. coli strains was determined by UV spectrophotometry with imipenem (100 mM) as substrate. Results: Resulting E. coli recombinant strains harboured hypothetical MBL-encoding genes. MICs of b-lactams showed decreased susceptibility to carbapenems only for E. coli (pFLA-1) and E. coli (pLON-1), expressing the MBL from E. flavus and E. longus, respectively. MBLs from different Erythrobacter spp. shared weak amino acid identity, ranging from 45% to 75% identity. They differed greatly from that of E. litoralis HTCC2594 (and NDM-1), sharing only 11% – 23% identity. Enzymatic activity against imipenem was detectable but weak in all these recombinant E. coli strains, except E. coli (pFLA-1), in which specific activity was significantly higher. Conclusions: Several chromosomally located MBLs have been identified from Erythrobacter spp. They share weak amino acid identity and are very weakly related to other acquired MBLs (10%–23%).

A novel Gram-negative, orange-pigmented, slightly halophilic, rod-shaped bacterium, strain T30T, was isolated from sediment from the South China Sea. Phylogenetic analysis showed that strain T30Twas a member of the genusErythrobacter, sharing highest 16S rRNA gene sequence similarities withErythrobacteraquimarisJCM 12189T(99.5 %) andErythrobactervulgarisDSM 17792T(99.0 %). Levels of DNA–DNA relatedness between strain T30Tand closely related strains ofErythrobacterspecies ranged from 14.5 to 56.9 %.The isolate lacked bacteriochlorophyllaand contained ubiquinone-10 as the predominant respiratory lipoquinone. The major fatty acids of this strain were C18 : 1ω7c(38.2 %) and C16 : 1ω7c/C16 : 1ω6c(17.4 %). The major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylcholine and phosphatidylglycerol. The DNA G+C content of strain T30Twas 59.5 mol%. On the basis of phenotypic and phylogenetic data, a novel species,Erythrobacter nanhaisediminissp. nov., is proposed; the type strain is T30T(=CGMCC 1.7715T=JCM 16125T).

Three Gram-negative, non-motile, non-spore-forming, slightly halophilic rods (strains SW-110T, SW-116 and SW-140) were isolated from sea water of a tidal flat of the Yellow Sea in Korea and subjected to a polyphasic taxonomic study. The three isolates did not produce bacteriochlorophyll a and were characterized chemotaxonomically by having ubiquinone-10 as the predominant respiratory lipoquinone and C18 : 1 ω7c and C17 : 1 ω6c as the major fatty acids. The DNA G+C content of the three isolates was between 62·2 and 62·9 mol%. Strains SW-110T, SW-116 and SW-140 showed no difference in their 16S rRNA gene sequences, and their mean level of DNA–DNA relatedness was 94·8 %. Phylogenetic analyses based on 16S rRNA gene sequences showed that the three strains form a distinct phylogenetic lineage within the cluster comprising Erythrobacter species. Similarities between the 16S rRNA gene sequences of strains SW-110T, SW-116 and SW-140 and the type strains of Erythrobacter species ranged from 98·4 % (with Erythrobacter longus) to 97·7 % (with Erythrobacter flavus). Levels of DNA–DNA relatedness between strains SW-110T, SW-116 and SW-140 and the type strains of all recognized Erythrobacter species were in the range 5·3–12·7 %. On the basis of polyphasic taxonomic data, strains SW-110T, SW-116 and SW-140 were classified as a novel Erythrobacter species, for which the name Erythrobacter aquimaris sp. nov. is proposed. The type strain is SW-110T (=KCCM 41818T=JCM 12189T).