To characterize the Fe(III)-reducing bacteria,enrichment cultures were initiated by inoculating deep-sea sediment from the South China Sea(SCS)into the media with hydrous ferric oxide(HFO)as the sole electron acceptor...To characterize the Fe(III)-reducing bacteria,enrichment cultures were initiated by inoculating deep-sea sediment from the South China Sea(SCS)into the media with hydrous ferric oxide(HFO)as the sole electron acceptor.As indicated by Meta 16S rDNA Amplicon Sequencing,the microorganisms related to Fe(III)-reduction in the enrichment cultures were mainly Shewanella and Enterobacter.A new facultative Fe(III)-reducing bacterium was obtained and identified as Enterobacter sp.Nan-1 based on its 16S rRNA gene sequence and physiological characterizations.Enterobacter sp.Nan-1 was not only a mesophilic bacterium capable of reducing HFO with a wide range of salinity(4,34,40,50 and 60 g L−1)efficiently,but also a piezotolerant bacterium that can proceed Fe(III)-reduction sustainedly at hydrostatic pressures between 0.1 and 50 MPa using glucose and pyruvate as carbon source.Furthermore,the geochemical characteristics of deep-sea sediment indicated that the microbial metabolism and iron reduction both remain active in the well-developed Fe(III)-reducing zone where the strain Nan-1 was obtained.To our knowledge,Enterobacter sp.Nan-1 could serve as a new applicative Fe(III)-reducing bacterium for future investigation on the iron biogeochemical cycle and diagenetic process of organic matter in the deep-sea environment.展开更多
Contamination of agricultural soils by heavy metals has become a major concern due to their toxic effects on plant growth,symbiosis and consequently the yields of crops. In the present study, to enhance plant growth i...Contamination of agricultural soils by heavy metals has become a major concern due to their toxic effects on plant growth,symbiosis and consequently the yields of crops. In the present study, to enhance plant growth in Cr（VI）-amended soils, novel metalresistant plant growth-promoting bacteria（PGPB） were isolated from a soil contaminated with industrial waste effluent. One of the bacterial isolates, identified as Enterobacter sp. C1 D by 16 S r RNA gene sequencing, was found to be multi-metal resistant in nature with excellent plant growth-promoting（PGP） traits. Mung bean（Vigna radiata var. GM4） inoculation with Enterobacter sp.C1 D significantly（P ＆lt; 0.01） increased root and shoot length, shoot and root weight, and chlorophyll content in a range of Cr（VI）treatments. Plant tolerance towards Cr（VI） measured as effective concentration showed higher values with Enterobacter sp. C1 Dtreated plants compared to un-inoculated plants. Root colonization study was also carried out using green fluorescence protein-labeled Enterobacter sp. C1 D under a hydroponic system. Confocal laser scanning microscopy of the plant roots showed heavy bacterial loads on the surface of the plant root specifically at the root tip and the point of root hair/lateral root formation. The results of PGP traits showed that elevated indole acetic acid levels and 1-aminocyclopropane-1-carboxylate deaminase activity enabled Enterobacter sp. C1 D to enhance V. radiata growth in Cr（VI）-amended soils, whereby it significantly increased plant tolerance towards elevated Cr（VI） concentrations.展开更多
基金the financial support by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB06020000)the Zhejiang Geological Prospecting Bureau Science Projects(No.201713)the Geological Fund of Zhejiang Province(No.20150012).
文摘To characterize the Fe(III)-reducing bacteria,enrichment cultures were initiated by inoculating deep-sea sediment from the South China Sea(SCS)into the media with hydrous ferric oxide(HFO)as the sole electron acceptor.As indicated by Meta 16S rDNA Amplicon Sequencing,the microorganisms related to Fe(III)-reduction in the enrichment cultures were mainly Shewanella and Enterobacter.A new facultative Fe(III)-reducing bacterium was obtained and identified as Enterobacter sp.Nan-1 based on its 16S rRNA gene sequence and physiological characterizations.Enterobacter sp.Nan-1 was not only a mesophilic bacterium capable of reducing HFO with a wide range of salinity(4,34,40,50 and 60 g L−1)efficiently,but also a piezotolerant bacterium that can proceed Fe(III)-reduction sustainedly at hydrostatic pressures between 0.1 and 50 MPa using glucose and pyruvate as carbon source.Furthermore,the geochemical characteristics of deep-sea sediment indicated that the microbial metabolism and iron reduction both remain active in the well-developed Fe(III)-reducing zone where the strain Nan-1 was obtained.To our knowledge,Enterobacter sp.Nan-1 could serve as a new applicative Fe(III)-reducing bacterium for future investigation on the iron biogeochemical cycle and diagenetic process of organic matter in the deep-sea environment.
基金supported by the Department of Science and Technology (DST), Government of India (No. SR/S4/ES-21/Baroda Window/P3)
文摘Contamination of agricultural soils by heavy metals has become a major concern due to their toxic effects on plant growth,symbiosis and consequently the yields of crops. In the present study, to enhance plant growth in Cr（VI）-amended soils, novel metalresistant plant growth-promoting bacteria（PGPB） were isolated from a soil contaminated with industrial waste effluent. One of the bacterial isolates, identified as Enterobacter sp. C1 D by 16 S r RNA gene sequencing, was found to be multi-metal resistant in nature with excellent plant growth-promoting（PGP） traits. Mung bean（Vigna radiata var. GM4） inoculation with Enterobacter sp.C1 D significantly（P ＆lt; 0.01） increased root and shoot length, shoot and root weight, and chlorophyll content in a range of Cr（VI）treatments. Plant tolerance towards Cr（VI） measured as effective concentration showed higher values with Enterobacter sp. C1 Dtreated plants compared to un-inoculated plants. Root colonization study was also carried out using green fluorescence protein-labeled Enterobacter sp. C1 D under a hydroponic system. Confocal laser scanning microscopy of the plant roots showed heavy bacterial loads on the surface of the plant root specifically at the root tip and the point of root hair/lateral root formation. The results of PGP traits showed that elevated indole acetic acid levels and 1-aminocyclopropane-1-carboxylate deaminase activity enabled Enterobacter sp. C1 D to enhance V. radiata growth in Cr（VI）-amended soils, whereby it significantly increased plant tolerance towards elevated Cr（VI） concentrations.
