The diversity of sulfate-reducing bacteria （SRB） from deep layers of deep-sea sediments [ more than 2 m bsf （below seafloor） ] of two sites （WO1 -3 and WPO1 -4） in a tropical West Pacific warm pool region was ch...The diversity of sulfate-reducing bacteria （SRB） from deep layers of deep-sea sediments [ more than 2 m bsf （below seafloor） ] of two sites （WO1 -3 and WPO1 -4） in a tropical West Pacific warm pool region was characterized by using molecular phylogenetic analysis. The results of culture-independent samples demonstrated that the dominant clones from both sites were related to Grampositive spore forming genus, Desulfotomaculum, which accounted for 36.8% of all the sequencing clones from Site WP01 - 3 and 62.8% from Site WP01 -4. However, the other SRB group which was generally reported to be predominant in the deep-sea sediments of other regions, δ- subclass of the proteobacteria was found to be in very low percentages. Therefore, it could be speculated that there existed a unique chemical environment in the deep-sea sediment of this warm pool region. When comparing the Desulfotomaculum sp. related sequences from both sites, it was revealed that though the Desulfotomaculum-like sequences from Site WP01 -3 were more diverse than those from Site WP01 -4, all these sequences from both sites showed high similarity and formed a new phylogenetically homogeneous cluster in the Desulfotomaculum genus which had never been reported before. Successful enrichment of SRB was only achieved from samples of Site WP01 -4 and the sequence analysis of culture-dependent samples further confirmed the dominance of Desulfotomaculum genus. But Desulfotomaculum-related sequences from culture-dependent and culture-independent samples belonged to two different clusters respectively. This difference showed the choice of cultivation to the microorganisms.展开更多
DDCl-1 type seismic profiler for deep sediment layers is a large scale marine survey equipment. Its penetrating strata depth may reach to 1 km. This equipment suits surveys for continental shelf,seafloor trench and ge...DDCl-1 type seismic profiler for deep sediment layers is a large scale marine survey equipment. Its penetrating strata depth may reach to 1 km. This equipment suits surveys for continental shelf,seafloor trench and geological structure under seafloor etc. It suits also geological environment surveys of seafloor resources.The working principle, block diagrams composition and echo signal processing characteristics are presented, and some typical strata profiles are shown.展开更多
The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we exa...The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we examine the mineralogical and geochemical composition of a sediment core(core CD-1)that was recovered from the southwestern margin of the Challenger Deep within the Mariana Trench.Major element abundances and rare-earth element patterns from these sediments require inputs from both terrigenous dust and locally sourced volcanic debris.We exploit a two-endmember mixing model to demonstrate that locally sourced volcanic material dominates the sediment supply to the Challenger Deep(averaging^72%).The remainder,however,is supplied by aeolian dust(averaging^28%),which is consistent with adjacent studies that utilized Sr-Nd isotopic data.Building on a growing database,we strengthen our understanding of Asian aeolian dust input into the northwestern Pacific,which ultimately improves our appreciation of sedimentation in,and around,the hadal zone.展开更多
Sediments of carbonate gravity flows and terrigenous debris turbidites, and normal bathyal deposits were found at the Shaiwa Section, Ziyun County, Guizhou Province, southwestern China. Through grain size analysis of...Sediments of carbonate gravity flows and terrigenous debris turbidites, and normal bathyal deposits were found at the Shaiwa Section, Ziyun County, Guizhou Province, southwestern China. Through grain size analysis of some typical sediments at this section, the changing patterns of the grain parameters and the grain size cumulations were recovered. Results show that the study area was deposited under turbidite control during the Late Permian period, which we also recognized at the outcrop section upon sedimentary characteristics of the sediments. In addition, fossils are abundant in the Upper Permian of the Shaiwa Section, including radiolarians, sponge spicules, bivalves, brachiopods, ammonoids and trace fossils. Radiolarians and siliceous sponge spicules are typical deep water assemblages. Bivalves are dominated by genera of Hunanopecten and Claraia , both showing deep water living characteristics. Ammonoids are composed of planktonic types, showing characteristics of smooth and flat shells. Brachiopods are dominated by a small and thin shelled assemblage, which are commonly flat in shape and usually of slight ornamentations on shells. In addition, trace fossils found at the Shaiwa Section are also common types of deep water facies. Thus, the fossil evidence of the Shaiwa Section also suggests a deep water environment, possibly from the bathyal slope to the basin margin facies, of the studied area during the Late Permian period.展开更多
Analyzed and calculated are pressure changes and body deformation of the sample inside of the corer in the process of sampling of deep-sea shallow sediment with a non-piston corer for gas hydrate investigation, Two co...Analyzed and calculated are pressure changes and body deformation of the sample inside of the corer in the process of sampling of deep-sea shallow sediment with a non-piston corer for gas hydrate investigation, Two conclusions are drawn： （1） the stress increments associated with the corer through the sampling process do not affect the stabilization of the gas hydrate; （2） the body deformation of the sample is serious and the ＂incremental filling ratio＂ （IFR） is less than unit, For taking samples with in-situ pressure and structure, combining with the design theories of the pressure tight corer, we have designed a kind of piston corer, named the gas hydrate pressure tight piston corer, Several tests on the sea have been conducted. Test results indicate that the piston corer has a good ability of taking sediment samples on the seafloor and maintaining their original in-situ pressure, meeting the requirement of exploration of gas hydrate in deep-sea shallow sediment layers.展开更多
The sinkage of a moving tracked mining vehicle is greatly af fected by the combined compression-shear rheological properties of soft deep-sea sediments. For test purposes, the best sediment simulant is prepared based ...The sinkage of a moving tracked mining vehicle is greatly af fected by the combined compression-shear rheological properties of soft deep-sea sediments. For test purposes, the best sediment simulant is prepared based on soft deep-sea sediment from a C-C poly-metallic nodule mining area in the Pacific Ocean. Compressive creep tests and shear creep tests are combined to obtain compressive and shear rheological parameters to establish a combined compressive-shear rheological constitutive model and a compression-sinkage rheological constitutive model. The combined compression-shear rheological sinkage of the tracked mining vehicle at dif ferent speeds is calculated using the Recur Dyn software with a selfprogrammed subroutine to implement the combined compression-shear rheological constitutive model. The model results are compared with shear rheological sinkage and ordinary sinkage(without consideration of rheological properties). These results show that the combined compression-shear rheological constitutive model must be taken into account when calculating the sinkage of a tracked mining vehicle. The combined compression-shear rheological sinkage decrease with vehicle speed and is the largest among the three types of sinkage. The developed subroutine in the Recur Dyn software can be used to study the performance and structural optimization of moving tracked mining vehicles.展开更多
Microbial community structures in the Arctic deep-sea sedimentary ecosystem are determined by organic matter input, energy availability, and other environmental factors. However, global warming and earlier ice-cover m...Microbial community structures in the Arctic deep-sea sedimentary ecosystem are determined by organic matter input, energy availability, and other environmental factors. However, global warming and earlier ice-cover melting are affecting the microbial diversity. To characterize the Arctic deep-sea sediment microbial diversity and its relationship with environmental factors, we applied Roche 454 sequencing of 16 S r DNA amplicons from Arctic deep-sea sediment sample. Both bacterial and archaeal communities＇ richness, compositions and structures as well as taxonomic and phylogenetic affiliations of identified clades were characterized. Phylotypes relating to sulfur reduction and chemoorganotrophic lifestyle are major groups in the bacterial groups; while the archaeal community is dominated by phylotypes most closely related to the ammonia-oxidizing Thaumarchaeota（96.66%） and methanogenic Euryarchaeota（3.21%）. This study describes the microbial diversity in the Arctic deep marine sediment（〉3 500 m） near the North Pole and would lay foundation for future functional analysis on microbial metabolic processes and pathways predictions in similar environments.展开更多
Tellurium is a sort of scattered rare element on the earth. Its concentration is very low in earth＇s crust, only 1.0 ng/g. However, it has extremely high abundance in Co-rich crusts, marine polymetallic nodules, deep...Tellurium is a sort of scattered rare element on the earth. Its concentration is very low in earth＇s crust, only 1.0 ng/g. However, it has extremely high abundance in Co-rich crusts, marine polymetallic nodules, deep-sea sediments and aerolites. To find out the origin of tellurium enrichment in deep-sea sediments, we analyzed and compared tellurium concentrations and helium isotope compositions in the magnetic parts and those in the bulk parts of deep-sea sediments. The result indicates that the helium content, 3He/4He ratio and tellurium concentration are obviously higher in the magnetic parts than those in the bulk parts. The 3He abundance varies synchronously with the tellurium concentration. 3He and Te have a distinct positive correlation with each other. It is the first time that the paper brings forward that the extreme enrichment of tellurium in deep-sea sediments, like helium isotope anomalies, probably results from the input of interplanetary dust particles （IDPs）. Similarly, the extreme enrichment of tellurium in marine polymetallic nodules and Co-rich crusts is possibly related to IDPs.展开更多
A depth profile of bacterial community structure in one deep-sea sediment core of the western Pacific ＂warm pool＂ （WP） was investigated and compared with that in a sediment sample from the eastern Pacific （EP） b...A depth profile of bacterial community structure in one deep-sea sediment core of the western Pacific ＂warm pool＂ （WP） was investigated and compared with that in a sediment sample from the eastern Pacific （EP） by phylogenetic analysis of 16S rDNA fragments. Five bacterial 16S rDNA clone libraries were constructed, and 133 clones with different restriction fragment length polymorphism （RFLP） patterns were sequenced. A phylogenetic analysis of these sequences revealed that the bacterial diversity in a sample from the WP was more abundant than that in the EP sample. The bacterial population in the sediment core of WP was composed of eight major lineages of the domain bacteria. Among them the γ-Proteobacteria was the predominant and most diverse group in each section of WP sediment core, followed by the α-Proteobacteria. The genus Colwellia belonging to γ-Proteobacteria was predominant in this sample. The shift of bacterial communities among different sections of the WP sediment core was δ-, ε-Proteobacteria, and Cytopahga-Flexibacteria-Bacteroides （CFB） group. The ratios between them in the bacterial communities all showed inversely proportional to the depth of sediment. The sequences related to sulphate reducing bacteria （SRB） were detected in every section. The bacterial community structure in this sediment core might be related to the environmental characteristics of the surface seawater of the western Pacific WP.展开更多
A deep-sea bacterium from the Pacific Ocean identified as Tenacibaculum sp. HMG1 was found to have strong malachite green（MG） degradation activity. The MG tolerance and decolorizing activities of strain HMG1 were co...A deep-sea bacterium from the Pacific Ocean identified as Tenacibaculum sp. HMG1 was found to have strong malachite green（MG） degradation activity. The MG tolerance and decolorizing activities of strain HMG1 were confirmed by bacterial growth and high-performance liquid chromatography（HPLC） analyses. Strain HMG1 was capable of removing 98.8% of the MG in cultures within 12 h and was able to grow vigorously at 20 mg/L MG. A peroxidase gene detected in the genome of strain HMG1 was found to be involved in the MG biodegradation process. The corresponding recombinant peroxidase（r POD） demonstrated high degradative activity at 1 000 mg/L MG. Based on the common candidate intermediates, strain HMG1 was inferred to have one primary MG degradation pathway containing r POD. In addition, five other candidate intermediates of the r POD-MG degradative process were detected. The optimal conditions for MG degradation were determined and showed that strain HMG1 and the r POD enzyme could maintain high bioactivity at a low temperature（20℃）, variable p H values（6.0–9.0）, higher salinities（100 mmol/L） and other factors, such as multiple metal ions, H2O2 and EDTA.MG-tolerant strain Tenacibaculum sp. HMG1 and its peroxidase have prospective applications as environmental amendments for MG degradation during coastal remediation.展开更多
The response of bacteria to various carbohydrates in the deep-sea sediments and the Antarctic soils was investigated using cellulose, chitin, and olive oil. It was found that the carbohydrates significantly increased ...The response of bacteria to various carbohydrates in the deep-sea sediments and the Antarctic soils was investigated using cellulose, chitin, and olive oil. It was found that the carbohydrates significantly increased the corresponding specific ectoenzyme activity （β- glucosidase, β-N-acetylglucosaminidase, lipase） in the samples from deep-sea sediments. In the case of Antarctic soil samples, the cellulose or olive oil amendments had minor or no effect on β-glucosidase or lipase activity, except the chitin which stimulated β- N-acetylglucosaminidase production. The responses of the bacteria in the deep-sea sediment sample WP02-3 and the Antarctic soil sample CC-TY2 towards the chitin amendment were further analyzed. Chitin amendments were shown to stimulate the ectoenzyme activity in all the tested sediments and the soils. The bacterial response before and after the carbohydrates amendments were compared by denaturing gradient gel electrophoresis and quantitative competitive polymerase chain reaction. Significant changes were found in the structure and density of the bacterial community in the deep sea sediments as compared to the Antarctic soil sample, where the effects were relatively lower. There was no change in the bacterial population in both studied samples in response to carbohydrates amendments. These data indicate that the bacterial communities in the oligotrophic deep-sea sediments are more dynamic than that in the Antarctic soils as they respond to the nutrient sources efficiently by regulation of ectoenzyme activity and/or changing community structure.展开更多
A protocol to coextract the microbial metagenomic DNA and RNA from deep-sea sediment was developed for the microbiological study of environmental samples. The obtained pure metagenomic DNA with the size larger than 23...A protocol to coextract the microbial metagenomic DNA and RNA from deep-sea sediment was developed for the microbiological study of environmental samples. The obtained pure metagenomic DNA with the size larger than 23 kb and stable RNA could be used directly for PCR and reverse transcription - PCR （ RT - PCR） respectively. The direct lysis including the treatments of SDS, proteinase and lysozyme was applied to acquiring the metagenomic DNA and RNA furthest. Prior to the lysis treatment, the glass bead and denaturing solution were added to enhance the lysis efficiency and keep the integrity of RNA respectively. Denaturing gradient gel electrophoresis （DGGE） was applied in accessing the microbial 16S rRNA diversity by PCR and RT -PCR amplification from a single extraction. The pattern obtained by this analysis revealed some differences between them, indicating the efficiency of the protocol in extracting the metagenomic DNA and total RNA from deep-sea sediment.展开更多
文摘The diversity of sulfate-reducing bacteria （SRB） from deep layers of deep-sea sediments [ more than 2 m bsf （below seafloor） ] of two sites （WO1 -3 and WPO1 -4） in a tropical West Pacific warm pool region was characterized by using molecular phylogenetic analysis. The results of culture-independent samples demonstrated that the dominant clones from both sites were related to Grampositive spore forming genus, Desulfotomaculum, which accounted for 36.8% of all the sequencing clones from Site WP01 - 3 and 62.8% from Site WP01 -4. However, the other SRB group which was generally reported to be predominant in the deep-sea sediments of other regions, δ- subclass of the proteobacteria was found to be in very low percentages. Therefore, it could be speculated that there existed a unique chemical environment in the deep-sea sediment of this warm pool region. When comparing the Desulfotomaculum sp. related sequences from both sites, it was revealed that though the Desulfotomaculum-like sequences from Site WP01 -3 were more diverse than those from Site WP01 -4, all these sequences from both sites showed high similarity and formed a new phylogenetically homogeneous cluster in the Desulfotomaculum genus which had never been reported before. Successful enrichment of SRB was only achieved from samples of Site WP01 -4 and the sequence analysis of culture-dependent samples further confirmed the dominance of Desulfotomaculum genus. But Desulfotomaculum-related sequences from culture-dependent and culture-independent samples belonged to two different clusters respectively. This difference showed the choice of cultivation to the microorganisms.
文摘DDCl-1 type seismic profiler for deep sediment layers is a large scale marine survey equipment. Its penetrating strata depth may reach to 1 km. This equipment suits surveys for continental shelf,seafloor trench and geological structure under seafloor etc. It suits also geological environment surveys of seafloor resources.The working principle, block diagrams composition and echo signal processing characteristics are presented, and some typical strata profiles are shown.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB06020204)the National Key Basic Research and Development Program of China(Nos.2017YFC0307704,2017YFC0307600)the Marine Geological Survey Program of China Geological Survey(No.DD20160218)
文摘The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we examine the mineralogical and geochemical composition of a sediment core(core CD-1)that was recovered from the southwestern margin of the Challenger Deep within the Mariana Trench.Major element abundances and rare-earth element patterns from these sediments require inputs from both terrigenous dust and locally sourced volcanic debris.We exploit a two-endmember mixing model to demonstrate that locally sourced volcanic material dominates the sediment supply to the Challenger Deep(averaging^72%).The remainder,however,is supplied by aeolian dust(averaging^28%),which is consistent with adjacent studies that utilized Sr-Nd isotopic data.Building on a growing database,we strengthen our understanding of Asian aeolian dust input into the northwestern Pacific,which ultimately improves our appreciation of sedimentation in,and around,the hadal zone.
基金the National Natural Science Foundationof China ( Nos. 40172012 and 40232025 ), the Australian Common wealth Government and Deakin University for the award of an Interna tional Postgraduate Research Scholarship (IPRS) to PYQ
文摘Sediments of carbonate gravity flows and terrigenous debris turbidites, and normal bathyal deposits were found at the Shaiwa Section, Ziyun County, Guizhou Province, southwestern China. Through grain size analysis of some typical sediments at this section, the changing patterns of the grain parameters and the grain size cumulations were recovered. Results show that the study area was deposited under turbidite control during the Late Permian period, which we also recognized at the outcrop section upon sedimentary characteristics of the sediments. In addition, fossils are abundant in the Upper Permian of the Shaiwa Section, including radiolarians, sponge spicules, bivalves, brachiopods, ammonoids and trace fossils. Radiolarians and siliceous sponge spicules are typical deep water assemblages. Bivalves are dominated by genera of Hunanopecten and Claraia , both showing deep water living characteristics. Ammonoids are composed of planktonic types, showing characteristics of smooth and flat shells. Brachiopods are dominated by a small and thin shelled assemblage, which are commonly flat in shape and usually of slight ornamentations on shells. In addition, trace fossils found at the Shaiwa Section are also common types of deep water facies. Thus, the fossil evidence of the Shaiwa Section also suggests a deep water environment, possibly from the bathyal slope to the basin margin facies, of the studied area during the Late Permian period.
基金The project was financially supported bythe National Natural science Foundation of China (Grant No.50675055)
文摘Analyzed and calculated are pressure changes and body deformation of the sample inside of the corer in the process of sampling of deep-sea shallow sediment with a non-piston corer for gas hydrate investigation, Two conclusions are drawn： （1） the stress increments associated with the corer through the sampling process do not affect the stabilization of the gas hydrate; （2） the body deformation of the sample is serious and the ＂incremental filling ratio＂ （IFR） is less than unit, For taking samples with in-situ pressure and structure, combining with the design theories of the pressure tight corer, we have designed a kind of piston corer, named the gas hydrate pressure tight piston corer, Several tests on the sea have been conducted. Test results indicate that the piston corer has a good ability of taking sediment samples on the seafloor and maintaining their original in-situ pressure, meeting the requirement of exploration of gas hydrate in deep-sea shallow sediment layers.
基金Supported by the National Natural Science Foundation of China(Nos.51274251,11502226)
文摘The sinkage of a moving tracked mining vehicle is greatly af fected by the combined compression-shear rheological properties of soft deep-sea sediments. For test purposes, the best sediment simulant is prepared based on soft deep-sea sediment from a C-C poly-metallic nodule mining area in the Pacific Ocean. Compressive creep tests and shear creep tests are combined to obtain compressive and shear rheological parameters to establish a combined compressive-shear rheological constitutive model and a compression-sinkage rheological constitutive model. The combined compression-shear rheological sinkage of the tracked mining vehicle at dif ferent speeds is calculated using the Recur Dyn software with a selfprogrammed subroutine to implement the combined compression-shear rheological constitutive model. The model results are compared with shear rheological sinkage and ordinary sinkage(without consideration of rheological properties). These results show that the combined compression-shear rheological constitutive model must be taken into account when calculating the sinkage of a tracked mining vehicle. The combined compression-shear rheological sinkage decrease with vehicle speed and is the largest among the three types of sinkage. The developed subroutine in the Recur Dyn software can be used to study the performance and structural optimization of moving tracked mining vehicles.
基金The National Natural Science Foundation of China under contract No.41121064the NSFC-Shandong Joint Fund for Marine Science Research Centers under contract No.U1406403the Science Foundation for Post Doctorate Research from the Chinese Academy of Sciences under contract No.2012M511072
文摘Microbial community structures in the Arctic deep-sea sedimentary ecosystem are determined by organic matter input, energy availability, and other environmental factors. However, global warming and earlier ice-cover melting are affecting the microbial diversity. To characterize the Arctic deep-sea sediment microbial diversity and its relationship with environmental factors, we applied Roche 454 sequencing of 16 S r DNA amplicons from Arctic deep-sea sediment sample. Both bacterial and archaeal communities＇ richness, compositions and structures as well as taxonomic and phylogenetic affiliations of identified clades were characterized. Phylotypes relating to sulfur reduction and chemoorganotrophic lifestyle are major groups in the bacterial groups; while the archaeal community is dominated by phylotypes most closely related to the ammonia-oxidizing Thaumarchaeota（96.66%） and methanogenic Euryarchaeota（3.21%）. This study describes the microbial diversity in the Arctic deep marine sediment（〉3 500 m） near the North Pole and would lay foundation for future functional analysis on microbial metabolic processes and pathways predictions in similar environments.
基金This work was supported by the National Natural Science Foundation of China(No.49873002)Key Basic Research Project of Ministry of Land and Mineral Resources(No.20010209).
文摘Tellurium is a sort of scattered rare element on the earth. Its concentration is very low in earth＇s crust, only 1.0 ng/g. However, it has extremely high abundance in Co-rich crusts, marine polymetallic nodules, deep-sea sediments and aerolites. To find out the origin of tellurium enrichment in deep-sea sediments, we analyzed and compared tellurium concentrations and helium isotope compositions in the magnetic parts and those in the bulk parts of deep-sea sediments. The result indicates that the helium content, 3He/4He ratio and tellurium concentration are obviously higher in the magnetic parts than those in the bulk parts. The 3He abundance varies synchronously with the tellurium concentration. 3He and Te have a distinct positive correlation with each other. It is the first time that the paper brings forward that the extreme enrichment of tellurium in deep-sea sediments, like helium isotope anomalies, probably results from the input of interplanetary dust particles （IDPs）. Similarly, the extreme enrichment of tellurium in marine polymetallic nodules and Co-rich crusts is possibly related to IDPs.
文摘A depth profile of bacterial community structure in one deep-sea sediment core of the western Pacific ＂warm pool＂ （WP） was investigated and compared with that in a sediment sample from the eastern Pacific （EP） by phylogenetic analysis of 16S rDNA fragments. Five bacterial 16S rDNA clone libraries were constructed, and 133 clones with different restriction fragment length polymorphism （RFLP） patterns were sequenced. A phylogenetic analysis of these sequences revealed that the bacterial diversity in a sample from the WP was more abundant than that in the EP sample. The bacterial population in the sediment core of WP was composed of eight major lineages of the domain bacteria. Among them the γ-Proteobacteria was the predominant and most diverse group in each section of WP sediment core, followed by the α-Proteobacteria. The genus Colwellia belonging to γ-Proteobacteria was predominant in this sample. The shift of bacterial communities among different sections of the WP sediment core was δ-, ε-Proteobacteria, and Cytopahga-Flexibacteria-Bacteroides （CFB） group. The ratios between them in the bacterial communities all showed inversely proportional to the depth of sediment. The sequences related to sulphate reducing bacteria （SRB） were detected in every section. The bacterial community structure in this sediment core might be related to the environmental characteristics of the surface seawater of the western Pacific WP.
基金The Scientific Research Project of Xiamen Southern Oceanographic Center under contract No.17GZP007NF03the China Ocean Mineral Resources R&D Association under contract No.DY-125-22-QY-18
文摘A deep-sea bacterium from the Pacific Ocean identified as Tenacibaculum sp. HMG1 was found to have strong malachite green（MG） degradation activity. The MG tolerance and decolorizing activities of strain HMG1 were confirmed by bacterial growth and high-performance liquid chromatography（HPLC） analyses. Strain HMG1 was capable of removing 98.8% of the MG in cultures within 12 h and was able to grow vigorously at 20 mg/L MG. A peroxidase gene detected in the genome of strain HMG1 was found to be involved in the MG biodegradation process. The corresponding recombinant peroxidase（r POD） demonstrated high degradative activity at 1 000 mg/L MG. Based on the common candidate intermediates, strain HMG1 was inferred to have one primary MG degradation pathway containing r POD. In addition, five other candidate intermediates of the r POD-MG degradative process were detected. The optimal conditions for MG degradation were determined and showed that strain HMG1 and the r POD enzyme could maintain high bioactivity at a low temperature（20℃）, variable p H values（6.0–9.0）, higher salinities（100 mmol/L） and other factors, such as multiple metal ions, H2O2 and EDTA.MG-tolerant strain Tenacibaculum sp. HMG1 and its peroxidase have prospective applications as environmental amendments for MG degradation during coastal remediation.
基金supported by the China Ocean Mineral Resources R&D Association(No.DYXM-115-02-2-01)the National Natural Science Foundation of China(No.40830213)the Hi-Tech Research and Development Program(863) of China(No.2007AA091904)
文摘The response of bacteria to various carbohydrates in the deep-sea sediments and the Antarctic soils was investigated using cellulose, chitin, and olive oil. It was found that the carbohydrates significantly increased the corresponding specific ectoenzyme activity （β- glucosidase, β-N-acetylglucosaminidase, lipase） in the samples from deep-sea sediments. In the case of Antarctic soil samples, the cellulose or olive oil amendments had minor or no effect on β-glucosidase or lipase activity, except the chitin which stimulated β- N-acetylglucosaminidase production. The responses of the bacteria in the deep-sea sediment sample WP02-3 and the Antarctic soil sample CC-TY2 towards the chitin amendment were further analyzed. Chitin amendments were shown to stimulate the ectoenzyme activity in all the tested sediments and the soils. The bacterial response before and after the carbohydrates amendments were compared by denaturing gradient gel electrophoresis and quantitative competitive polymerase chain reaction. Significant changes were found in the structure and density of the bacterial community in the deep sea sediments as compared to the Antarctic soil sample, where the effects were relatively lower. There was no change in the bacterial population in both studied samples in response to carbohydrates amendments. These data indicate that the bacterial communities in the oligotrophic deep-sea sediments are more dynamic than that in the Antarctic soils as they respond to the nutrient sources efficiently by regulation of ectoenzyme activity and/or changing community structure.
文摘A protocol to coextract the microbial metagenomic DNA and RNA from deep-sea sediment was developed for the microbiological study of environmental samples. The obtained pure metagenomic DNA with the size larger than 23 kb and stable RNA could be used directly for PCR and reverse transcription - PCR （ RT - PCR） respectively. The direct lysis including the treatments of SDS, proteinase and lysozyme was applied to acquiring the metagenomic DNA and RNA furthest. Prior to the lysis treatment, the glass bead and denaturing solution were added to enhance the lysis efficiency and keep the integrity of RNA respectively. Denaturing gradient gel electrophoresis （DGGE） was applied in accessing the microbial 16S rRNA diversity by PCR and RT -PCR amplification from a single extraction. The pattern obtained by this analysis revealed some differences between them, indicating the efficiency of the protocol in extracting the metagenomic DNA and total RNA from deep-sea sediment.
