The colonization of Hansschlegelia zhihuaiae S113 and its degradation of the herbicide chlorimuron-ethyl in the cucumber rhizosphere was investigated. The results reveal that S113 colonized the cucumber roots (2.14 × 10cells per gram of roots) and were able to survive in the rhizosphere (maintained for 20 d). The root exudates promoted colonization on roots and increased the degradation of chlorimuron-ethyl by S113. Five organic acids in cucumber-root exudates were detected and identified by HPLC. Citric acid and fumaric acid significantly stimulated S113 colonization on cucumber roots, with 18.4 and 15.5% increases, respectively, compared with the control. After irrigation with an S113 solution for 10 days, chlorimuron-ethyl could not be detected in the roots, seedlings, or rhizosphere soil, which allowed for improved cucumber growth. Therefore, the degradation mechanism of chlorimuron-ethyl residues by S113 in the rhizosphere could be applied in situ for the bioremediation of chlorimuron-ethyl contaminated soil to ensure crop safety.

Heavy metal pollution can affect the immune capability of organisms. We evaluated the effect of cadmium (Cd) on the defense responses of the Pacifi c oyster Crassostrea gigas to Listonella anguillarum challenge. The activities of several important defensive enzymes, including superoxide dismutase (SOD), glutathione peroxidase (GPx), acid phosphatase (ACP), Na + , K + -ATPase in gills and hepatopancreas, and phenoloxidase-like (POL) enzyme in hemolymph were assayed. In addition, the expression levels of several genes, including heat shock protein 90 (HSP90), metallothionein (MT), and bactericidal/permeability increasing (BPI) protein were quantifi ed by fl uorescent quantitative PCR. The enzyme activities of SOD, ACP, POL, and GPx in hepatopancreas, and the expression of HSP90 were down-regulated, whereas GPx activity in the gill, Na + , K + -ATPase activities in both tissues, and MT expression was increased in Cdexposed oysters post L . anguillarum challenge. However, BPI expression was not signifi cantly altered by co-stress of L . anguillarum infection and cadmium exposure. Our results suggest that cadmium exposure alters the oysters' immune responses and energy metabolism following vibrio infection.

The halophyte Suaeda salsa can grow in heavy metal-polluted areas along intertidal zones having high salinity. Since phytochelatins can eff ectively chelate heavy metals, it was hypothesized that S . salsa possessed a phytochelatin synthase (PCS) gene. In the present study, the cDNA of PCS was obtained from S . salsa (designated as SsPCS ) using homologous cloning and the rapid amplifi cation of cDNA ends (RACE). A sequence analysis revealed that SsPCS consisted of 1 916 bp nucleotides, encoding a polypeptide of 492 amino acids with one phytochelatin domain and one phytochelatin C domain. A similarity analysis suggested that SsPCS shared up to a 58.6% identity with other PCS proteins and clustered with PCS proteins from eudicots. There was a new kind of metal ion sensor motif in its C-terminal domain. The SsPCS transcript was more highly expressed in elongated and fi bered roots and stems ( P < 0.05) than in leaves. Lead and mercury exposure signifi cantly enhanced the mRNA expression of SsPCS ( P < 0.05). To the best of our knowledge, SsPCS is the second PCS gene cloned from a halophyte, and it might contain a diff erent metal sensing capability than the fi rst PCS from Thellungiella halophila . This study provided a new view of halophyte PCS genes in heavy metal tolerance.

A Gram-variable, short-rod-shaped, motile, spore-forming, strictly aerobic and alkaliresistant bacterium, designed strain J-3, was isolated from farmland soil sampled in Yancheng city, Jiangsu province, China. Optimal growth occurred at 30 °C, pH 7.0-8.0 and 0.5 % (w/v) NaCl. Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain J-3 was most closely related to Paenibacillusripae HZ1 (96.8 %), followed by Paenibacillussputi KIT00200-70066-1 (94.7 %). The major cellular fatty acids were anteiso-C15 : 0 and C16 : 0. The dominant respiratory quinone was menaquinone-7 and the DNA G+C content was 41.2 mol%. The major polar lipids of strain J-3 were aminolipid, phospholipid, diphosphatidylglycerol, phosphatidylglycerol, phosphoaminolipid and phosphatidylethanolamine. The diagnostic diamino acid of the cell-wall peptidoglycan was meso-diaminopimelic acid. On the basis of genotypic and phenotypic data, strain J-3 represents a novel species of the genus Paenibacillus, for which the name Paenibacillus yanchengensis sp. nov. is proposed. The type strain is J-3 (=KCTC 33926=CGMCC 1.16455).

A yellow-coloured bacterial strain, designated F-4 T , was isolated from a farmland soil sample from Qianshan, Anhui province, China. Strain F-4 T was Gram-stain-negative, strictly aerobic, oval-shaped, motile (by gliding) and non-sporeforming. Growth occurred at 20-35 C (optimum, 30 C), at pH 6.0-8.0 (pH 7.0) and with 0-1.0 % (w/v) NaCl (0 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain F-4 T belonged to the genus Taibaiella. 16S rRNA gene sequence similarity values between strain F-4 T and the type strains of the three recognized species of the genus Taibaiella, Taibaiella koreensis KACC 17171 T , Taibaiella soli KCTC 42277 T and Taibaiella chishuiensis JCM 19637 T , were 98.1, 96.4 and 95.9 %, respectively. The predominant respiratory quinone was MK-7, with MK-8 as a minor component. The major polar lipids of strain F-4 T were three unidentified lipids, two unidentified aminolipids, three unidentified phospholipids, an unidentified aminophospholipid and phosphatidylethanolamine. The major cellular fatty acids were iso-C 15 : 0 , iso-C 15 : 1 G and iso-C 17 : 0. The G+C content of the genomic DNA based on total genome calculations was 51.3 mol%. The major polyamine of strain F-4 T was homospermidine. The average nucleotide identity and the digital DNA-DNA hybridization values for draft genomes between strain F-4 T and strain THG-DT86 T were 79.8 and 22.6 %, respectively. On the basis of the genotypic and phenotypic data presented here, strain F-4 T represents a novel species of the genus Taibaiella, for which the name Taibaiella helva sp. nov. is proposed. The type strain is F-4 T (=KCTC 62442 T =CGMCC 1.13562 T).