Ecological risk assessment of trace metals in sediments and their effect on benthic organisms from the south coast of Zhejiang province, China.

To explore the ecological risks of trace metals in sediments and their relationship with benthic organisms, 12 trace metals were analyzed and the macrobenthos were identified in the sediments collected from the south coast of Zhejiang province which belongs to the East China Sea. Spatially, the concentrations of most trace metals were high in the estuary, except for Ba and Sr. There was no obvious enrichment for trace metals, except that the concentration of Cd slightly exceeded the coastal background. The ecological risks calculated by the concentrations of Cr, Cd, Cu, Zn, Pb, and Ni in sediments showed that the methods based on sediment quality guidelines could judge the ecological risk more intuitively than the methods based on background value (PN, PLI, RI). The significant correlations between ecological risks and benthos density and biomass revealed the negative impact of trace metals at high concentrations on macrobenthic survival in sediments.

Muricauda antarctica sp. nov., a marine member of the Flavobacteriaceae isolated from Antarctic seawater.

A Gram-stain-negative, rod-shaped bacterium with appendages, designated Ar-22(T), was isolated from a seawater sample collected from the western part of Prydz Bay, near Cape Darnley, Antarctica. Strain Ar-22(T) grew optimally at 35 °C, at pH 7.5 and in the presence of 1-3% (w/v) NaCl. The isolate was positive for casein, gelatin and Tween 20 decomposition and negative for H2S production and indole formation. Chemotaxonomic analysis showed that MK-6 was the major isoprenoid quinone and phosphatidylethanolamine was the major polar lipid. The major fatty acids were iso-C(17:0) 3-OH, iso-C(15:1) G, iso-C(15:0) and C(16:1)ω7c/iso-C(15:0) 2OH. The genomic DNA G+C content was 44.8 mol%. Comparative 16S rRNA gene sequence analysis revealed that strain Ar-22(T) is closely related to members of the genus Muricauda, sharing 94.2-97.3% sequence similarity with the type strains of species of the genus Muricauda and being most closely related to the Muricauda aquimarina. Phylogenetic analysis based on the 16S rRNA gene sequence comparison confirmed that strain Ar-22(T) formed a deep lineage with Muricauda flavescens. Sequence similarity between strain Ar-22(T) and Muricauda ruestringensis DSM 13258(T), the type species of the genus Muricauda, was 96.9%. Strain Ar-22(T) exhibited mean DNA-DNA relatedness values of 40.1%, 49.4% and 25.7% to M. aquimarina JCM 11811(T), M. flavescens JCM 11812(T) and Muricauda lutimaris KCTC 22173(T), respectively. On the basis of phenotypic and genotypic data, strain Ar-22(T) represents a novel species of the genus Muricauda, for which the name Muricauda antarctica sp. nov. (type strain Ar-22(T) =CGMCC 1.12174(T) = JCM 18450(T)) is proposed.

Citricoccus zhacaiensis sp. nov., isolated from a bioreactor for saline wastewater treatment.

A Gram-positive, neutrophilic, non-motile and non-spore-forming actinobacterium, strain FS24(T), was isolated from a bioreactor treating salt-containing wastewater. This isolate grew in the presence of 0-15 % (w/v) NaCl and at 10-37 degrees C. The optimum NaCl concentration for growth of FS24(T) was 5 % (w/v) at 37 degrees C or 1 % (w/v) at 25 degrees C. Chemotaxonomic analysis revealed MK-9(H(2)) as the predominant menaquinone and the major cellular polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, four unknown glycolipids, two unknown phospholipids and an unknown lipid. The major fatty acids were anteiso-C(15 : 0 ), iso-C(15 : 0), iso-C(16 : 0 ) and anteiso-C(17 : 0). The genomic DNA G+C content was 66.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain FS24(T) clustered with members of the genus Citricoccus, exhibiting high sequence similarity to the 16S rRNA gene sequences of the type strains of Citricoccus alkalitolerans (98.9 %) and Citricoccus muralis (98.8 %), respectively. The DNA-DNA relatedness values of strain FS24(T) to C. alkalitolerans DSM 15665(T) and C. muralis DSM 14442(T) were 54 and 39 %, respectively. On the basis of phenotypic and genotypic data, strain FS24(T) represents a novel species of the genus Citricoccus, for which the name Citricoccus zhacaiensis sp. nov. is proposed. The type strain is FS24( T) (=CGMCC 1.7064(T) =JCM 15136(T)).