北极海洋沉积物细菌和古菌群落结构分析

This study was to investigate bacterial and archaeal community structure of pan-Arctic Ocean sediments by pyrosequencing.In total,investigation of three marine sediments revealed 15 002 bacterial and 4 362 archaeal operational taxonomic units(OTUs) at the 97% similarity level.Analysis of community structure indicated that these three samples had high bacterial and archaeal diversity.The most relatively abundant bacterial group in Samples CC1 and R05 was Proteobacteria,while Firmicutes was dominant in Sample BL03.Thaumarchaeota was the most relatively abundant archaeal phylum in Samples CC1 and R05,and the relative abundance of Thaumarchaeota was almost as high as that of Euryarchaeota in Sample BL03.These two phyla accounted for nearly 100% of the archaeal OTUs.δ-Proteobacteria and γ-Proteobacteria were the two most relatively abundant classes at Proteobacterial class level,and their relative abundance was more than 60% in Samples CC1 and R05.There were also differences in the top 10 relatively abundant bacterial and archaeal OTUs among the three samples at the 97% similarity,and only 12 core bacterial OTUs were detected.Overall,this study indicated that there were distinct microbial communities and many unique OTUs in these three samples.     

黄海西北近岸沉积物中细菌群落空间分布特征

采用16S rDNA文库和变性梯度凝胶电泳(DGGE)技术,对黄海西北部3个近岸站位沉积物中细菌群落多样性及空间分布特征进行了调查和解析。对表层沉积物16S rDNA序列统计表明,各站位细菌群落多样性很高,γ-和δ-变形菌纲分别占克隆序列总数的20%~32%,是沉积物中的绝对优势类群。DGGE图谱分析表明,同一站位中不同深度的细菌群落结构相似性较高,而不同站位间群落结构相差较远。研究表明在黄海西北近岸沉积物中细菌群落多样性较高,优势类群明显,在较小尺度范围内群落结构的垂直变化不明显。     

Phylogenetic analysis of bacterial community in deep-sea sediment from the western Pacific “warm pool”

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.     

Temporal patterns among meiofauna and macrofauna taxa related to changes in sediment geochemistry at an abyssal NE Atlantic site

Two major size classes of the sediment community, meiofauna and macrofauna, and four classes of lipid compounds, fatty acids, alkanes, alcohols and sterols, were investigated using multicorer and USNEL boxcorer samples, collected during six cruises over a two year period (September 1996 to September–October 1998), at the Porcupine Abyssal Plain ( 48° 50′N 16° 30′W, 4850 m depth) within the framework of the MAST 3 BENGAL project. This site was known to be subject to seasonality in the input of organic matter to the seafloor. Results are given for each faunal size class in terms of taxonomic structure at the level of phylum, class or order, depending on the taxon, and for the dominant faunal components in terms of density and vertical distribution. For each lipid compound class, results are given in concentration and vertical distribution. The taxonomic structure of each size class did not change within the study period. Total meiofaunal and macrofaunal densities were particularly high, probably reflecting the high quantity and quality of organic matter inputs to the site. The dominant components of the two size classes presented different temporal patterns in their responses to changes in their environment. Populations of meiofaunal species, a foraminiferan and an opheliid polychaete, which inhabit the surface or sub-surface of sediment and feed on phytodetritus, responded with a rapid increase in abundance to a pulse of organic input in summer 1996. The macrofaunal polychaetes showed a lagged response to the same event by slowly increasing in density. Other components of the sediment community, that can live deeper in the sediment, moved down the sediment column, in response to 1) the impoverishment and bioturbation of the surface layer, and 2) the downward mixing of organic matter in the sediment by larger organisms. In this study, different temporal patterns were demonstrated for the first time in different size classes of the sediment community, and in the biological and environmental parameters that were studied simultaneously.     

宁波北仑港冬季浮游细菌多样性研究

采用分子生物学方法对宁波北仑港冬季水体中的浮游细菌多样性进行了研究.提取水样中细菌基因组总DNA,以细菌16S rDNA通用引物进行PCR扩增,扩增产物经分子克隆、测序与序列分析,对水样中的细菌建立了16S rDNA克隆文库和系统发生树.结果表明,浮游细菌群落具有较高的多样性,34个克隆子分属2个不同的细菌类群,6个克隆子属于未知类群,优势细菌类群为Pro-teobacteria类群（变形菌类群）,占80%;细菌优势类群顺序为β-Proteobacteria类群（32.5%）、γ-Proteobacteria类群（25%）、α-Proteobacteria类群（15%）、ε-proteobacteria类群（7.5%）、Firmicutes类群（厚壁菌类群）（5%）.这一结果与近年来国内外有关港口微生物多样性的报道较为一致.用DNAStar中Clustalw程序从测序的40个克隆子中选出17个OTU进行系统发育分析,同样表明浮游细菌多样性较强.     

中国明对虾混合养殖池塘沉积物微生物群落比较研究

微生物群落在养殖池塘生态系统中发挥着重要的作用,与环境质量及养殖动物的生长和疾病暴发密切相关。为了考察中国明对虾不同混养模式中的微生态状况,本研究基于 16S rRNA 基因的高通量测序技术,比较了 6 种不同中国明对虾混 养池塘沉积物微生物群落的差异。结果表明,6 种混养池塘沉积物的主要微生物均为变形菌门 （Proteobacteria） 和放线菌门（Actinobacteria）,与褐牙鲆的混养,会导致变形菌门丰度升高,同时抑制放线菌门的生长。中国明对虾、海蜇、菲律宾蛤仔混养具有最高的沉积物微生物群落丰富度和多样性。通过对微生物功能进行预测发现,化能异养和含硫化合物的呼吸是中国对虾混养池塘沉积物微生物群落的主要功能。中国明对虾、海蜇、菲律宾蛤仔混养沉积物中部分细菌的某特异性富集,可以提高沉积物中溶解氧量并促进化学物污染物的降解。综上所述,中国明对虾、海蜇、菲律宾蛤仔混养模式在 6 种不同中国明对虾混养池塘中微生态状况最佳。     

渤海沉积物中细菌群落结构和基因丰度的空间分布特征

This study investigated differences in the community structure and environmental responses of the bacterial community in sediments of the Bohai Sea.Illumina high-throughput sequencing technology and real-time PCR were used to assay the bacterial 16S rRNA genes in the surface sediments of 13 sampling stations in the Bohai Sea.The results showed that sediments at the majority of the 13 sampling stations were contaminated by heavy metal mercury.The main phyla of bacteria recorded included Proteobacteria(52.92%),Bacteroidetes(11.76%),Planctomycetes(7.39%),Acidobacteria(6.53%)and Chloroflexi(4.97%).The genus with the highest relative abundance was Desulfobulbus(4.99%),which was the dominant genus at most sampling stations,followed by Lutimonas and Halioglobus.The main factors influencing bacterial community structure were total organic carbon,followed by depth and total phosphorus.The content of lead,cadmium,chromium,copper and zinc had a consistent effect on community structure.Arsenic showed a negative correlation with bacterial community structure in most samples,while the impact of mercury on community structure was not significant.The bacterial community in sediment samples from the Bohai Sea was rich in diversity and displayed an increase in diversity from high to low latitudes.The data indicated that the Bohai Sea had abundant microbial resources and was rich in bacteria with the potential to metabolize many types of pollutants.     

Microbial diversity in the sediments of the southern Mariana Trench

Microbial diversity in the abyssal sediments beneath the seafloor of 30,94,and 151cm near the southern end of the Mariana Trench was analyzed in the Illumina HiSeq 2500 platform.Results show that the microbial populations were dominated by bacteria but merely no archaea were identifi ed at the three depths.In the bacterial community,Proteobacteria and Firmicutes dominated the total taxon tags,followed by Bacteroidetes,Actinobacteria,Planctomycetes,Cyanobacteria,and Chloroflexi,which together account for over 99%of the total population.Similar to that in the seawater in the trench,the operational taxonomic units(OTUs)belonging to Gammaproteobacteria from the sediment samples showed high abundance.However,common bacterial OTUs in the water of the trench including Nitrospirae and Marinimicrobia were hardly found in the sediments from the southern Mariana Trench or the hadal region.Therefore,this study documented for the first time the compositions of microbial diversity in the trench sediments,revealed the difference in microbial diversity in water and sediment of the trench and will enrich the knowledge on the microbial diversity in the abyssal areas.     

Microbial diversity in polluted harbor sediments I: Bacterial community assessment based on four clone libraries of 16S rDNA

Bacteria, as the most abundant sediment organism, play a major role in the fate of pollutants. Therefore, many pollutant-related bacteria have been studied in harbor sediments, yet the entire bacterial profiles have not been reported. The bacterial diversity and community structures from sediments in Victoria Harbor (Hong Kong), including two polluted (VH and VHW) and two adjacent (open oceanic, TLC; estuary discharge affected, PC) sites, were characterized by analyses of four 16S rDNA clone libraries. Upon comparisons of RFLP patterns from 254 clones in the libraries, 178 unique phylotypes were retrieved. LIBSHUFF and Rarefaction analyses indicated that the sediment bacterial communities at the four sites showed high 16S rDNA richness and were significantly different from each other. Phylogenetic analysis of full-length 16S rDNA revealed 19 bacterial phyla in Victoria Harbor sediments. γ- and δ-proteobacteria, holophaga/acidobacteria, and planctomycetales were recorded in all the libraries. In addition, γ- and δ-proteobacteria were dominant at all sites (33.33–11.67%). Besides these two phyla, ε-proteobacteria, firmicutes, aminobacterium, holophaga/acidobacteria and bacteroidetes were judged to be major components of a given library since they constituted 10% or more of the total OTUs of the given library. The cyanobacteria, verrucomicrobia, β-proteobacteria, aminobacterium, chlorofiexi, and candidate division OP1, OP8 were detected in minor proportions in various libraries. A portion of the clones were only distantly related to sequences in the GenBank, suggesting bacteria in Victoria Harbor sediments were unique and diversified.     

南极菲尔德斯半岛潮间带沉积物细菌的多样性及分离菌产酶测定

摘要:南极菲尔德斯半岛具有多种不同特征的生态地理微环境,如长城科考站、企鹅岛、生物湾与黄金湾流域、半岛南部、碧玉滩等。这些区域因水文地质、动植物分布、人类活动程度等不同而具有明显的生态地理差异。本研究从这些微环境海岸潮间带采集了7份代表性沉积物样品,采用16S rRNA基因高通量测序方法,对其细菌类群的多样性以及环境理化因子的影响进行了比较分析;同时采用常规可培养鉴定方法,对样品的分离菌株产酶状况进行了初步测定。结果表明：整体上看,所有样品的细菌类群主要分布在45门、104纲、442属当中,表现出比较高的多样性。其中,优势菌门Proteobacteria主要分布在半岛南部、碧玉滩和生物湾潮间带沉积物物中,优势菌门Bacteroidetes主要分布在企鹅岛两侧和黄金湾潮间带沉积物,长城站潮间带沉积物的优势门为Firmicutes。相似生态微环境的潮间带沉积物具有不同的优势菌门和纲;而不同生态微环境潮间带沉积物却具相同的优势菌门和纲。有机氮（TON）、NH4+-N、NO3--N、PO43--P、NO2--N含量与企鹅岛两侧、生物湾、黄金湾潮间带沉积物的菌群多样性具有相关性,其中TON对生物湾样品的影响最大,而有机碳（TOC）对所有样品的影响较小。分离菌株的产酶实验表明：在企鹅岛、生物湾、黄金湾等动物频繁出没的潮间带样品中,蕴藏着一批产淀粉酶、酪蛋白酶、脂肪酶、七叶苷酶、过氧化氢酶能力较强菌株,这为今后进一步的应用开发提供了宝贵的低温产酶菌株来源。 关键词: 菲尔德斯半岛; 潮间带沉积物; 细菌类群多样性; 产酶菌株     

Microbial diversity in Huguangyan Maar Lake of China revealed by high-throughput sequencing

Huguangyan Maar Lake is a typical maar lake in the southeast of China. It is well preserved and not disturbed by anthropogenic activities. In this study, microbial community structures in sediment and water samples from Huguangyan Maar Lake were investigated using a high-throughput sequencing method. We found significant differences between the microbial community compositions of the water and the sediment. The sediment samples contained more diverse Bacteria and Archaea than did the water samples. Actinobacteria, Betaproteobacteria, Cyanobacteria, and Deltaproteobacteria predominated in the water samples while Deltaproteobacteria, Anaerolineae, Nitrospira, and Dehalococcoidia were the major bacterial groups in the sediment. As for Archaea, Woesearchaeota (DHVEG-6), unclassified Archaea, and Deep Sea Euryarchaeotic Group were detected at higher abundances in the water, whereas the Miscellaneous Crenarchaeotic Group, Thermoplasmata, and Methanomicrobia were significantly more abundant in the sediment. Interactions between Bacteria and Archaea were common in both the water column and the sediment. The concentrations of major nutrients (NO^3-, PO4^3-, SiO3^2- and NH4^+) shaped the microbial population structures in the water. At the higher phylogenetic levels including phylum and class, many of the dominant groups were those that were also abundant in other lakes;however, novel microbial populations (unclassified) were often seen at the lower phylogenetic levels. Our study lays a foundation for examining microbial biogeochemical cycling in sequestered lakes or reservoirs.     

Meiobenthos in estuary part of ha long bay (gulf of tonkin, south china sea, vietnam)

The distribution of the taxonomical composition and the density of meiobenthos depending on some factors of environment has been studied in bottom sediments of the northern estuary part of Ha Long Bay (Cua Luc estuary). The basic factor of influence on meiobenthic community structure was the granulometric composition of sediment. The greatest taxonomic diversity is noted in the silted sands, lowest — in the silty sediments. The density of meiobenthic community was higher in the silty sediments. Slightly expressed correlation between the density of nematodes and the percentage of silty particles in the sediments is detected (Spearman rank correlation coefficient was 0.49±0.21, p=0.035). The nematodes were dominant at all stations. In total, representatives of 66 species of nematodes belonging to 17 families and 52 genera were identified.     

黄渤海底栖纤毛虫分子多样性和生物地理学研究

对中国渤海、北黄海和南黄海三个海域底栖纤毛虫的分子多样性与生物地理学进行了研究。从底栖真核微生物18S rDNA的焦磷酸测序数据中提取出隶属于纤毛门的序列,并在此基础上分析了纤毛虫群落的阿尔法多样性和贝塔多样性。结果表明,纤毛虫操作分类单元的丰富度在渤海比北黄海和南黄海都高,但夏冬两季无显著差异。在所有检测的环境因子中,水体深度与阿尔法多样性的相关性最强。就纤毛虫群落组成上看,总体上旋唇纲的序列及操作分类单元丰富度均占优势地位（占比分别为77.0%和66.5%）;旋唇纲主要由环毛亚纲以及未能进一步分类的类群组成。底栖纤毛虫群落结构在三个海域之间显著不同,但夏冬两季无显著差异。从各主要类群的相对比例来看,唯有侧口纲的序列比例在三个区域间呈现显著的不同。偏门特尔分析表明,相对于地理距离和环境因子而言,水体深度在调控底栖纤毛虫群落结构中扮演者更为重要的角色。本研究同时也发现,超过60%的操作分类单元未能被进一步分类到纲或目级水平,约45%的操作分类单元与GenBank数据库中已描述种类的序列相似度低于或等于97%,表明在近海沉积物中可能存在大量待发现的纤毛虫类群或物种。本研究发现底栖纤毛虫阿尔法多样性从北黄海到南黄海降低的趋势,这一点与之前基于形态学方法的调查结果相似。然而,测序数据显示旋唇纲是最主要类群,而形态学调查表明前口纲和核残迹纲是主要类群。本文也探讨了可能造成分子与形态学研究结果差异的一些潜在原因。     

Nematode species distribution patterns at the Håkon Mosby Mud Volcano (Norwegian Sea)

The Håkon Mosby Mud Volcano (HMMV) is a methane seep that is densely populated by the bacteria Beggiatoa spp. as well as by tubeworms of the Family Siboglinidae. Analyses of samples from seven stations located in five different habitats (bare sediments, bacterial mats, siboglinid fields, sediments with small patches of siboglinids and areas of ‘normal’ sea floor) revealed differences in the density and species‐level diversity of nematode communities. Total densities increased from stations inside the mud volcano and on its rim towards the ‘normal’ areas outside the volcano. Nematode species diversity was similar in samples from the siboglinid fields and the bare HMMV sediments. However, the sediment with patches of siboglinids collected outside the volcano was characterised by a diverse nematode community comprising 47 species, whereas the control sediments without siboglinids yielded only 27 species. The nematode assemblage at the bacterial mat site included only two identified species, Halomonhystera disjuncta and Sabatieria ornata, with H. disjuncta being strongly dominant. Terschellingia distlamphida, S. ornata and Aponema ninae dominated nematode communities at the siboglinid fields and in bare HMMV sediments. Species dominating at stations inside the caldera were found in comparable low densities in the sediment with siboglinid patches collected outside the volcano, but were missing in the background samples, where species of Endeolophos, Acantholaimus and Desmoscolex were dominant. Species diversity generally decreased with sediment depth. A subsurface‐dwelling nematode community was observed in the siboglinid fields and the bare sediments. Background sediments showed a sharp decline with 18–20 species at 0–2 cm versus three species at 3–5 cm sediment depth. The trophic composition of the nematode fauna at the HMMV showed a prevalence of deposit feeders at almost all stations, whereas background sediments exhibited a uniform distribution of non‐selective and selective deposit feeders and epistrate feeders. The high percentage of deposit feeders inside the mud volcano could be related to the grain‐size distribution and the significantly higher bacterial biomass compared to the control sediments.     

东太平洋海隆深海热液区沉积物古菌多样性分析

采用PCR-RFLP方法对东太平洋海隆深海热液区3个站位沉积物中的古菌多样性进行了初步研究.结果显示,从古菌16S rRNA基因文库中随机挑取的296个阳性克隆分属奇古菌门（Thaumarchaeota,47.64%）、广古菌门（Euryarchaeota,44.93%）、泉古菌门（Crenarchaeota,6.77%）和未分类古菌（0.68%）,其中优势菌群为奇古菌门的亚硝化侏儒菌属（Nitrosopumilus,35.47%）和广古菌门的热原体纲（Thermoplasmata,27.03%）,DHVE3、DHVE5、DHVE6、MBGB和MBGE类群在沉积物样品中也均有发现.另外,3个站位沉积物中古菌类群组成存在差异,S5-TVG1站位样品文库的97个古菌克隆分属奇古菌门（49.48%）、广古菌门（49.48%）和泉古菌门（1.03%）,S14-TVG10站位样品文库的103个古菌克隆由奇古菌门（84.47%）和广古菌门（15.53%）组成,S16-TVG12站位样品文库的96个古菌克隆包括广古菌门（71.88%）、泉古菌门（19.79%）、奇古菌门（6.25%）和未分类古菌（2.08%）.研究结果表明,东太平洋海隆深海热液区沉积物中古菌多样性丰富,存在着许多新的古菌菌群;不同站位古菌菌群结构以及多样性存在差异,这与其所处环境的热液活动密切相关.     

大洋表层沉积物中甲烷代谢古菌群落的组成及分布特征

海洋沉积物中的甲烷代谢微生物是甲烷循环的关键参与者,其代谢过程对大气甲烷浓度及全球气候变化具有显著影响,研究其在全球大洋沉积物中的组成及分布特征是探究微生物介导甲烷循环的基础。采用焦磷酸454高通量测序测定甲烷代谢保守功能基因mcrA(Methyl coenzyme–M reductase A)分析全球大洋沉积物中甲烷代谢微生物群落的组成和多样性;结合荧光实时定量PCR技术检测了古菌和甲烷代谢古菌的丰度分布特征。与其他海洋生境对比,大洋沉积物中甲烷代谢古菌群落结构单一,大西洋和印度洋的α多样性指数显著高于太平洋(p<0.05)。在大洋沉积物样品中鉴定到3个目的甲烷代谢古菌,即甲烷杆菌目(Methanobacteriales)、甲烷八叠球菌目(Methanosarcinales)和甲烷微菌目(Methanomicrobiales),其中甲烷微菌目占绝对优势,并主要由一簇未知类群(暂名Oceanic Sediments Dominant group,OSD group)组成。大洋沉积物的古菌16S rRNA基因丰度(湿重,下同)平均为8.81×10⁶ copie...     

Effect of solid to solution ratio on biogenic silica determination in coastal sediments

The method of DeMaster (1981) for measuring biogenic silica (BSi) in marine sediments was modified. We found a considerable effect of the solid to solution (S/S) ratio on BSi determination in coastal sediments. The BSi contents determined by DeMaster’s method were overestimated due to the contribution of clay mineral-derived extractable Si at a low S/S ratio (<1 g l⁻¹), and incomplete recovery of BSi was observed due to incomplete extraction when using a high S/S ratio (>2 g l⁻¹). For BSi analysis of coastal sediment samples, the BSi content of representative samples must be measured using various S/S ratios to determine the appropriate S/S ratio in order to minimize the contribution of extractable Si derived from clay minerals and to obtain sufficiently efficient extraction with 1% Na₂CO₃ before actual sample measurement. One way to determine the appropriate S/S ratio is to use artificial sediment which has a theoretical Si and clay mineral content similar to the sediment sample composition. Using artificial sediment, the S/S ratio of 2 g l⁻¹ seems appropriate for measuring the BSi content of the coastal sediments investigated in this study, because 99.6% recovery can be achieved.     

西太平洋多金属结核区表层沉积物细菌群落结构及其对沉积扰动的响应

本文基于大洋第48航次在西太平洋马尔库斯 威克海山多金属结核区采集的6个表层沉积物样品的高通量测序结果,开展底栖细菌群落结构调查,共获得253012条序列,分属于41个门、85个纲、189个目、261个科和322个属。其中,变形菌纲(Proteobacteria)为优势类群,分为γ 、α 和δ 三个亚群,分别占总序列条数的24.76%、20.21%和6.48%。绿弯菌门(Chloroflexi)、酸杆菌门(Acidobacteria)、芽单胞菌门(Gemmatimonadetes)、浮霉菌门(Planctomycetes)、放线菌门(Actinobacteria)、拟杆菌门(Bacteroidetes)及硝化螺旋菌门(Nitrospirae)等类群的序列数和属种较丰富。对序列条数大于1%的OTU(operational taxonomic units)分析,共获得优势菌群23个目,包含6个优势科,10个优势属,其中,铁锰功能细菌占10.20%,主要来自交替单胞菌属(Alteromonas)(6.90%)、假交替单胞菌属(Pseudoalteromonas)(1.80%)和希瓦氏菌属(Shewanella)(1.00%)等,另外还存在参与氮和硫元素循环的种属。PICRUSt功能预测分析显示结核区细菌主要涉及信号转导、蛋白转运、原核生物固碳、群体感应、能量转换、氨基酸和嘧啶代谢等功能。BC1826站位与其他站位相比,细菌多样性较低。结合沉积柱粒度分析结果,推测BC1826站位微生物群落结构的差异与沉积扰动有关,两者具有一定的响应关系。与已有研究成果汇总对比发现,西太平洋结核区与东太平洋结核区的细菌群落组成结构有较大差异。     

红树植物拟海桑及其亲本的根际细菌群落特征分析

植物根际微生物群落能够从亲本传递给子代, 从而影响植物的表型。野外调查发现, 海桑属(Sonneratia)红树植物自然杂交杂种拟海桑在野外通常比亲本生长更为强壮, 表现出极强的生存优势。为探究这一现象的原因, 本研究从根际微生物角度出发, 利用细菌16S rRNA基因高通量测序技术, 对采自海南省东寨港的三种红树植物拟海桑(S. × gulngai)及其亲本海桑(S. caseolaris)和杯萼海桑(S. alba)的根际土壤进行根际细菌群落特征分析。结果表明, 三种红树植物根际细菌群落多样性高, 种类丰富, 分属于30门242科351属, 其中变形菌门(Proteobacteria)为最优势门, 在各个样本中丰度超过40%, 子代拟海桑继承亲本的根际微生物多数都属于这一类群。研究发现, 子代拟海桑与两亲本的根际细菌类群组成在门水平存在显著差异, 其中酸杆菌门(Acidobacteria)和放线菌门(Actinobacteria)在子代拟海桑中丰度分别为4.3%和6.5%, 显著高于亲本1%~2%的含量; 在亲本杯萼海桑中, 丰度高达19.8%的栖热菌门(Thermi)在子代中丰度仅有1%, 而热袍菌门(Thermotogae)(5%)甚至消失。总之, 子代拟海桑与亲本杯萼海桑的根际微生物群落组成相对于亲本海桑表现出更大的差异性。土壤理化性质分析发现, 子代拟海桑的土壤全氮(total nitrogen, TN)含量显著低于亲本, 含量相差3倍以上, 相关性分析表明, TN浓度与菌群中的浮霉菌门(Planctomycetes)、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)丰度显著负相关。通过功能预测分析发现, 子代拟海桑微生物群落中与基础代谢相关的碳水化合物、氨基酸、能量以及脂质代谢相关的功能基因丰度显著都高于亲本, 表现出代谢能力的增强。本研究认为, 子代拟海桑对亲本的根际土壤微生物进行了选择性继承, 菌群组成更为合理, 在保持菌群高度多样性的同时, 一些根际促生菌的含量增加, 使菌群基础代谢能力增加, 更有利于子代拟海桑的生长。     

山东省近岸海域沉积物类型及变化趋势

文章依据山东省近岸海域表层沉积物调查资料,分析了沉积物粒度的时空变化特征及其影响因素。结果显示:2020年,山东省近岸海域表层沉积物粒径总体呈由近岸向远海逐渐变小的趋势,其中,粉砂含量最高,平均66.45%;砂次之,平均26.78%;黏土含量较低,平均6.77%。沉积物不同粒级组分具有明显的空间分布差异性,类型包含粉砂、砂质粉砂、粉砂质砂和砂,以粉砂为主,占调查站位的61.9%。2016—2020年,山东省近岸海域表层沉积物整体呈现粗化的趋势,其中,日照、青岛、潍坊和滨州近岸海域粗化趋势较为明显,东营次之,烟台和威海粗化程度最低。沉积物粒度时空特征的主要影响因素包含物源、区域水动力条件(如,渤海和黄海海流、山东省沿岸流等)及沿海海岸工程建设情况,具体的影响机制仍需进一步调查研究。本研究成果可以为山东省近岸海域底质类型变化分析和海岸带保护与利用提供参考。