Three novel umami peptides derived from the alcohol extract of the Pacific oyster(Crassostrea gigas):identification,characterizations and interactions with T1R1/T1R3 taste receptors

Oyster(Crassostrea gigas),the main ingredient of oyster sauce,has a strong umami taste.In this study,three potential umami peptides,FLNQDEEAR(FR-9),FNKEE(FE-5),and EEFLK(EK-5),were identified and screened from the alcoholic extracts of the oyster using nano-HPLC-MS/MS analysis,i Umami-Scoring Card Method(i Umami-SCM)database and molecular docking(MD).Sensory evaluation and electronic tongue analysis were further used to confirm their tastes.The threshold of the three peptides ranged from 0.38 to 0.55 mg/m L.MD with umami receptors T1R1/T1R3 indicated that the electrostatic interaction and hydrogen bond interaction were the main forces involved.Besides,the Phe592 and Gln853 of T1R3 were the primary docking site for MD and played an important role in umami intensity.Peptides with two Glu residues at the terminus had stronger umami,especially at the C-terminus.These results contribute to the understanding of umami peptides in oysters and the interaction mechanism between umami peptides and umami receptors.

Species composition and distribution of common Crassostrea and Saccostrea oysters along the coast of Hainan Island

Oyster cultivation is a pivotal economic industry in Hainan Island,South China,where a high oyster species diversity is shown.However,the specific distribution and biodiversity of oyster resources in the island have remained unclear.To elucidate the diversity of oyster species and their distribution there,307 oyster samples were collected from 29 sites in the intertidal zone around the island,and were identified using both morphological and molecular approaches.A minimum of 12 oyster species were identified in taxonomy,including Crassostrea species(C.gigas angulata,C.sikamea,C.iredalei,C.dianbaiensis,C.talonata,C.ariakensis,and C.hongkongensis),and Saccostrea species(S.malabonensis,S.mordax,S.echinata,S.circumsuta,and S.mordoides).The results revealed a remarkable diversity of oyster species along the coast of the island.Particularly noteworthy are that S.malabonensis and S.mordax constituted 36%and 22%of the collected specimens,respectively.This study provided a comprehensive overview on current state of oyster biodiversity in Hainan,serving as a valuable reference for conservation and research on species distribution and resource dynamics in oyster populations.

Spatial compartmentalization and temporal stability of associated microbiota in Pacific oyster Crassostrea gigas

The Pacific oyster Crassostrea gigas,one of the most exploited molluscs in the world,has suffered from massive mortality in recent decades,and the occurrence mechanisms have not been well characterized.In this study,to reveal the relationship of associated microbiota to the fitness of oysters,temporal dynamics of microbiota in the gill,hemolymph,and hepatopancreas of C.gigas during April 2018-January 2019 were investigated by 16 S rRNA gene sequencing.The microbiota in C.gigas exhibited tissue heterogeneity,of which Spirochaetaceae was dominant in the gill and hemolymph while Mycoplasmataceae enriched in the hepatopancreas.Co-occurrence network demonstrated that the gill microbiota exhibited higher inter-taxon connectivity while the hemolymph microbiota had more modules.The richness(Chao 1 index)and diversity(Shannon index)of microbial community in each tissue showed no significant seasonal variations,except for the hepatopancreas having a higher richness in the autumn.Similarly,beta diversity analysis indicated a relatively stable microbiota in each tissue during the sampling period,showing relative abundance of the dominant taxa exhibiting temporal dynamics.Results indicate that the microbial community in C.gigas showed a tissue-specific stability with temporal dynamics in the composition,which might be essential for the tissue functioning and environmental adaption in oysters.This work provides a baseline microbiota in C.gigas and is helpful for the understanding of host-microbiota interaction in oysters.

Non-Targeted Metabolomics Reveals the Metabolic Alterations in Response to Artificial Selective Breeding in the Fast-Growing Strains of Pacific Oyster

Pacific oyster(Crassostrea gigas)is one of the most important mollusks cultured all around the world.Selective breeding programs of Pacific oysters in China is initiated since 2006 and developed the genetically improved strain with fast-growing trait.However,little is known about the metabolic signatures of the fast-growing trait.In the present study,the non-targeted metabolomics was performed to analyze the metabolic signatures of adductor muscle tissue in one-year old Pacific oysters from fast-growing strain and the wild population.A total of 7767 and 10174 valid peaks were extracted and quantified in ESI^(+)and ESI^(−)modes,resulting in 399 and 381 annotated metabolites,respectively.PCA and OPLS-DA revealed that considerable separation among samples from fastgrowing strain and wild population,suggesting the differences in metabolic signatures.Meanwhile,81 significantly different metabolites(SDMs)were identified in the comparisons between fast-growing strain and wild population,based on the strict thresholds.It was found that there were highly correlation and conserved coordination among these SDMs.KEGG enrichment analysis indicated that the SDMs were tightly related to pantothenate and CoA biosynthesis,steroid hormone biosynthesis,riboflavin metabolism,and arginine and proline metabolism.Of them,the CoA biosynthesis and metabolism,affected by pantetheine and pantothenic acid,might be important for the growth of Pacific oysters under artificial selective breeding.The study provides the comprehensive views of metabolic signatures in response to artificially selective breeding,and is helpful to better understand the molecular mechanism of fastgrowing traits in Pacific oysters.

Characterisation of the Bacteria and Archaea Community Associated with Wild Oysters, At Three Possible Restoration Sites in the North Sea

With 85% of the global oyster reefs destroyed, there is an urgent need for large scale restoration to benefit from the ecosystem services provided by biogenic oyster reefs and their associated biodiversity, including microorganisms that drive marine biogeochemical cycles. This experiment established a baseline for the monitoring of the bacterial and archaeal community associated with wild oysters, using samples from their immediate environment of the Voordelta, with cohabiting Crassostrea gigas and Ostrea edulis, Duikplaats with only C. gigas attached to rocks, and the Dansk Skaldyrcentre, with no onsite oysters. The microbial profiling was carried out through DNA analysis of samples collected from the surfaces of oyster shells and their substrate, the sediment and seawater. Following 16S rRNA amplicon sequencing and bioinformatics, alpha indices implied high species abundance and diversity in sediment but low abundance in seawater. As expected, Proteobacteria, Bacteroidetes, Firmicutes and Thaumarchaeota dominated the top 20 OTUs. In the Voordelta, OTUs related to Colwellia, Shewanella and Psychrobium differentiated the oysters collected from a reef with those attached to rocks. Duikplaats were distinct for sulfur-oxidizers Sulfurimonas and sulfate-reducers from the Sva 0081 sediment group. Archaea were found mainly in sediments and the oyster associated microbiome, with greater abundance at the reef site, consisting mostly of Thaumarchaeota from the family Nitrosopumilaceae. The oyster free site displayed archaea in sediments only, and algal bloom indicator microorganisms from the Rhodobacteraceae, Flavobacteriaceae family and genus [Polaribacter] huanghezhanensis, in addition to the ascidian symbiotic partner, Synechococcus. This study suggests site specific microbiome shifts, influenced by the presence of oysters and the type of substrate.

Near-infrared spectroscopy method for rapid proximate quantitative analysis of nutrient composition in Pacific oyster Crassostrea gigas

Glycogen,amino acids,fatty acids,and other nutrient components affect the flavor and nutritional quality of oysters.Methods based on near-infrared reflectance spectroscopy(NIRS)were developed to rapidly and proximately determine the nutrient content of the Pacific oyster Crassostreagigas.Samples of C.gigas from 19 costal sites were freeze-dried,ground,and scanned for spectral data collection using a Fourier transform NIR spectrometer(Thermo Fisher Scientific).NIRS models of glycogen and other nutrients were established using partial least squares,multiplication scattering correction first-order derivation,and Norris smoothing.The R_(C) values of the glycogen,fatty acids,amino acids,and taurine NIRS models were 0.9678,0.9312,0.9132,and 0.8928,respectively,and the residual prediction deviation(RPD)values of these components were 3.15,2.16,3.11,and 1.59,respectively,indicating a high correlation between the predicted and observed values,and that the models can be used in practice.The models were used to evaluate the nutrient compositions of 1278 oyster samples.Glycogen content was found to be positively correlated with fatty acids and negatively correlated with amino acids.The glycogen,amino acid,and taurine levels of C.gigas cultured in the subtidal and intertidal zones were also significantly different.This study suggests that C.gigas NIRS models can be a cost-effective alternative to traditional methods for the rapid and proximate analysis of various slaughter traits and may also contribute to future genetic and breeding-related studies in Pacific oysters.

Biological oyster shell waste enhances polyphenylene sulfide composites and endows them with antibacterial properties

To date,there is no research that deals with biological waste as fillers in polyphenylene sulfide(PPS).In this study,oyster shells were recycled and treated to prepare thermally-treated oyster shells(TOS),which were used as PPS fillers to make new bio-based antibacterial composite materials.The effect of varying the content of TOS was studied by means of structure and performance characterization.PPS/TOS composites were demonstrated to have an antibacterial effect on the growth of E coli and S.aureus.Qualitative analysis showed that when the TOS content was≥30%and 40%,the composite materials had an apparent inhibition zone.Quantitative analysis showed that the antibacterial activity increased with the TOS content.Fourier transform infrared spectroscopy indicated the formation of hydrogen bonds between the molecular chains of TOS and PPS and the occurrence of a coordination reaction.At 10%TOS,the composite tensile strength reached a maximum value of 72.5 MPa,which is 9.65%higher than that of pure PPS.The trend of bending properties is the same as that of tensile properties,showing that the maximum property was reached for the composite with 10%TOS.At the same time,the crystallinity and contact angle were the highest,and the permeability coefficient was the lowest.The fatigue test results indicated that for the composite with 10%TOS,the tensile strength was 23%lower than static tensile strength,and the yield strength was 10%lower than the static yield strength.The results of the study showed that TOS not only could reduce the cost of PPS,but also could impart antibacterial properties and enhance the mechanical and,barrier properties,the thermostability,as well as the crystallinity.

Detection and quantification of Pb and Cr in oysters using laser-induced breakdown spectroscopy

The quantitative determination of heavy metals in aquatic products is of great importance for food security issues.Laser-induced breakdown spectroscopy(LIBS)has been used in a variety of foodstuff analysis,but is still limited by its low sensitivity when targeting trace heavy metals.In this work,we compare three sample enrichment methods,namely drying,carbonization,and ashing,for increasing detection sensitivity by LIBS analysis for Pb and Cr in oyster samples.The results demonstrate that carbonization can remove a significant amount of the contributions of organic elements C,H,N and O;meanwhile,the signals of the metallic elements such as Cu,Pb,Sr,Ca,Cr and Mg are enhanced by3–6 times after carbonization,and further enhanced by 5–9 times after ashing.Such enhancement is not only due to the more concentrated metallic elements in the sample compared to the dried ones,but also the unifying of the matter in carbonized and ashed samples from which higher plasma temperature and electron density are observed.This condition favors the detection of trace elements.According to the calibration curves with univariate and multivariate analysis,the ashing method is considered to be the best choice.The limits of detection of the ashing method are 0.52 mg kg-1 for Pb and0.08 mg kg-1 for Cr,which can detect the presence of heavy metals in the oysters exceeding the maximum limits of Pb and Cr required by the Chinese national standard.This method provides a promising application for the heavy metal contamination monitoring in the aquatic product industry.

The dual-function of bioactive peptides derived from oyster (Crassostrea gigas) proteins hydrolysates

Oysters(Crassostrea gigas)have a wide range of functionality due to their nutritional and bioactive components. However, the bioactive peptides of oyster proteins are rarely reported, particularly their antidiabetes effects and antioxidants. Oyster proteins were extracted from fresh oysters using phosphatebuffered saline and simulated gastrointestinal digestion was performed. The degree of hydrolysis(DH), structural characterization, molecular weight(Mw)distribution, free amino acid, anti-diabetic activity, and antioxidant activity were studied during in vitro simulated gastrointestinal digestion. The results showed that the α-glucosidase inhibitory activity, α-amylase inhibitory activity, DPPH radical scavenging activity, and ABTS radical scavenging activity of the oyster protein gastrointestinal digest were increased(P < 0.05)from 0 to 33.96%, from 9.17% to 44.22%, from 9.01 μg trolox/mg protein to 18.48 μg trolox/mg protein, and from 21.44 μg trolox/mg protein to 56.21 μg trolox/mg protein, respectively. Additionally, the DH, β-turn structure, fluorescence intensity, free amino acid, and short peptide content(Mw < 1 000 Da)increased in the simulated gastrointestinal digestion. These results indicate that the digestive hydrolysates obtained from oyster proteins could be used as natural anti-diabetic and antioxidant agents.

Preparation of Iron-Pillared Bentonite/Oyster Shell Composite and Phosphate Adsorption in Water

Iron-pillared bentonite(FB)was prepared by Fe(III)modified bentonite,and then the composites(FB-OS)were prepared by iron-pillared bentonite and oyster shell powder.The composites were characterized by FTIR,SEM,TGA,and EDS,and the phosphorus removal test was carried out.The results showed that FB-OS contained a large amount of CaO.Its structure was compact,but there were gaps in it.The maximum bending stress and compressive strength were 43.7 N and 0.927 MPa,respectively.The phosphorus removal test showed that the phosphorus removal rate of FB-OS was more than 90%,and measured the maximum adsorption capacity was 48.31 mg/g.A large amount of spherical products were produced on the surface and inside of FB-OS after phos-phorus removal,it was speculated that spherical products were amorphous calcium phosphate in the paper.Ana-lysis indicated that there was chemical adsorption during phosphorus removal.The kinetic equation of phosphorus adsorption by FB-OS was qt=10:193t/1+2:574t (R^(2)=0.995).The adsorption rate was mainly controlled by outerfilm diffusion and intraparticle diffusion.

黄河口西南侧小岛河河口天然牡蛎礁的牡蛎种群结构

牡蛎礁是生态系统服务价值高、但退化最严重及受关注度最高的海洋生境之一,牡蛎礁修复亦成为国际海洋生态修复的热点。掌握牡蛎自然种群状况及动态变化是评估牡蛎礁修复效果的基础。目前,我国天然牡蛎礁的牡蛎种群状况相关的背景资料较为缺乏。在黄河口西南侧的小岛河河口新发现天然活体牡蛎礁,但该牡蛎礁曾被大规模的商业采捕,亟需推进针对性的保护和修复研究工作。基于2021年11月对该牡蛎礁开展的牡蛎种群生态调查,分析其种类组成、年龄结构及生长特征。结果显示:该牡蛎礁分布有近江牡蛎(Crassostrea ariakensis)和长牡蛎(Crassostrea gigas)。牡蛎礁上以活体牡蛎为主,死亡牡蛎壳体数仅占6.1%—6.7%。活体牡蛎的密度和生物量分别为(2811±778)个/m^(2)和(21.97±30.43)kg/m^(2),近江牡蛎较多,其密度和生物量分别占比55.7%和76.4%。近江牡蛎和长牡蛎的年龄分别介于0+—4+龄和0+—2+龄,它们都以壳高介于30—40 mm及壳质量<5 g的0+龄个体数量居多(>80%)。近江牡蛎的壳体形态参数均值都高于同龄组长牡蛎的相应值。两种牡蛎壳体均呈负异速增长,不同龄级的壳体延展方向不同。拟合von Bertalanffy生长方程得到,近江牡蛎和长牡蛎的渐近壳高分别为286 mm和173 mm,估算的拐点年龄分别为5.47龄和2.56龄,两种牡蛎的生长曲线分布存在极显著差异(P<0.001)。以上结果表明,小岛河河口的天然牡蛎礁的牡蛎自然种群资源较丰富,具有高密度、低龄和低死亡率等特点,有较好的活力和扩张潜力,有利于被采捕后的礁体的恢复。两种牡蛎中,近江牡蛎因其具有较高的生物量和较长的生长年龄,对礁体形成和扩繁可能更为重要。建议对该天然牡蛎礁及牡蛎种群开展周期>3年的原位保护、修复和连续监测计划。

Purification of β-Glucan of Oyster Mushroom (Pleurotus pulmonarius) and Its Application in Model Food

Mushrooms are recognized as sources of β-glucan. The aim of this study was to purify β-glucan from oyster mushrooms (Pleurotus pulmonarius) by alkaline extraction. The extracted β-glucan was added to a cracker recipe and the sensory, physical and estimated glycemic index of the final product were evaluated. Optimum extraction parameters were determined to be 80˚C, 90 minutes and 30% KOH. The β-glucan crackers had a glycemic index ranging from 88.07 to 67.32, while glucose had a glycemic index of 100. Based on the sensory study, it can be concluded that crackers enriched with β-glucan and possessing functional qualities may meet consumer expectations.

牡蛎养殖对大鹏澳环境因子与浮游菌落扰动研究

为评估牡蛎养殖对典型半封闭海湾环境及其生态系统的影响,深入理解其在海洋环境治理和修复中的地位和作用,采用高通量测序技术,对位于典型城市半封闭海湾——大鹏澳的牡蛎养殖区4个季节的水体菌落结构和功能变化进行了分析,并对比了养殖区与对照区在水体和沉积物环境因子的差异特征。结果表明,牡蛎养殖对大鹏澳水体营养盐等环境因子的扰动相对较小,但其生物沉积作用却增强了海区总有机碳(Total organic carbon,TOC)、硫化物(Sulfide,Sul)和部分重金属的富集。高通量测序结果显示,冬季牡蛎养殖区中的绿弯菌门、脱硫杆菌门和放线菌门等菌落的相对丰度显著高于对照区(p<0.05)。冗余分析(Redundancy analysis,RDA)结果揭示了硅酸盐(SiO32-)、海水表面温度(Sea surface temperature,SST)和盐度是影响冬季牡蛎养殖区与对照区水体菌落结构差异的主要环境因子。此外,基于FAPROTAX模型预测的水体菌落生物地球化学功能分析表明,冬季牡蛎养殖区细菌介导的氮(N)和硫(S)元素的生物地球化学作用显著高于对照区(p<0.05)。综上,牡蛎养殖对大鹏澳海水菌落结构组成有一定的扰动,但其影响程度和范围受到了理化因子的季节性变化和水文条件等综合因素的制约。同时,牡蛎养殖也促进了N和S的生物地球化学循环。

黄岐湾三倍体牡蛎养殖区浮游植物群落特征及其影响因子分析

为研究三倍体牡蛎养殖区浮游植物群落特征及其影响因子,于2021年12月—2022年9月,对福建省连江县黄岐湾三倍体牡蛎养殖区开展逐月调查,并分析了浮游植物种类组成、丰度变化及其与环境因子的相关性。结果表明:养殖区浮游植物共有6门65属133种,其中硅藻门101种,甲藻门28种,蓝藻门、金藻门、裸藻门和原生动物门各1种,以广温广盐种最为常见且丰度占绝对优势,优势种为中肋骨条藻(Skeletonema costatum)和柔弱拟菱形藻(Pseudo-nitzschia delicatissima),优势度分别为0.798和0.027;浮游植物丰度月平均值范围为1.80×10^(4)~4.14×10^(6)cells/L,平均值为5.33×10^(5)cells/L,湾外养殖区丰度显著高于湾内(P<0.05);浮游植物多样性水平较高,群落结构较稳定;冗余分析显示,影响浮游植物优势种丰度的主要环境因子为总磷、活性磷酸盐、盐度和化学需氧量,其中,中肋骨条藻受水温、活性磷酸盐影响最大,柔弱拟菱形藻受Si/P值影响最大。研究表明,中肋骨条藻的高优势度与其广温广盐特性、较强的光适应生理特征及海水中丰富的硅酸盐有关;在磷相对限制的河口海湾,磷含量和盐度是影响浮游植物优势种丰度的主要环境因子。

牡蛎壳微粉改性水泥基复合材料性能及微观结构研究

以牡蛎壳粉部分替换传统水泥基材料,在实现牡蛎壳废物利用的同时可有效降低建材成本。利用牡蛎壳粉作为普通硅酸盐水泥掺合料,探讨其不同掺杂量及不同粉磨方式对水泥胶砂强度及安定性的影响,确定了牡蛎壳粉的适宜添加量,并用XRD、SEM及EDS等测试分析手段表征不同掺量下胶凝试块的结构及性能变化。实验结果表明,牡蛎壳的球磨方式对水泥胶砂强度有明显影响,掺加湿法球磨牡蛎壳粉的胶凝材料的强度高于相应的掺加干法球磨的样品。牡蛎壳粉的掺加量为5%时,试样的抗压强度和抗折强度分别达到49.2 MPa和7.55 MPa,显著高于未掺加的空白样品。通过安定性实验制得的试样经过预养、沸煮之后,表面均光滑、无裂纹,体积无明显膨胀或收缩,表明掺杂牡蛎壳粉的胶凝材料安定性良好。微观结构表征结果显示牡蛎壳粉在水泥胶凝材料中独立存在,主要起惰性填充作用。利用牡蛎壳微粉部分替代水泥基材料是可行的,既可以改善水泥基材料综合性能,又能节约材料成本、减少环境污染,具有良好的应用前景。

茄子与平菇、甘蓝、甘薯间作对其长势、产量及根际环境的影响

为避免因茄子连年种植导致的土传病害增加而对茄子生产造成影响,形成健康、生态的解决办法,以茄子不间作为对照,研究分析了茄子与平菇、甘蓝、甘薯3种作物分别间作后对其长势、产量及根际环境的影响。结果表明:与对照相比,茄子与3种作物间作对茄子株高日均生长量、茎粗、单株坐果数、单果质量、667 m^(2)平均产量以及根际土壤干质量、含水量、EC值、碳氮比、有机碳含量、无机碳含量、有机质含量、速效磷含量均未造成显著影响;茄子与甘蓝间作较与平菇、甘薯间作可显著降低土壤干质量和速效钾含量,且较对照分别降低了8.58%和11.11%,这有利于土壤孔隙度的增加,同时较对照极显著提高了茄子根际细菌总量,显著提高了根际真菌总量及根际细菌与真菌总量比值,分别较对照提高114.44%、42.18%和49.56%,这有助于茄子连作障碍的消减及土传病害的防治;茄子与平菇间作极显著降低了根际土壤的pH值,较对照降低5.36%,极显著降低了土壤全碳含量和全氮含量,分别降低16.99%和17.10%,但显著提高了土壤速效氮含量,增幅达36.10%,极显著提高了根际细菌总量和真菌总量,分别提高71.84%和156.98%;茄子与甘薯间作,极显著降低了根际土壤的pH值,降幅达7.39%,但显著提高了土壤速效钾含量和根际真菌总量,极显著增加了根际细菌总量,增幅分别达27.76%、56.98%和99.67%。综合上述分析认为,茄子与甘蓝间作有利于改善土壤团粒结构,丰富、稳定土壤生态系统,有助于作物植株健康生长,但间作时需要及时补充钾肥;而茄子与平菇、甘薯间作会降低土壤pH值,提高土壤肥力,可用于盐碱土或“生”土的改良。

改性剂对高密度聚乙烯复合材料的性能研究

采用回收的牡蛎壳经高温煅烧改性后为增强填料,马来酸酐接枝聚乙烯(PE-g-MAH)为改性剂与高密度聚乙烯采用熔融共混法制备了纳米复合材料。使用电子万能拉力机、X射线衍射仪(XRD)和差示扫描量热仪(DSC)对复合材料的结构、形貌和结晶性能进行了表征。探究了改性剂以及牡蛎壳粉含量对高密度聚乙烯复合材料综合性能的影响。结果表明:煅烧后的牡蛎壳粉可以提升复合材料的力学性能,且改性剂可以很好改善牡蛎壳粉与高密度聚乙烯之间的相容性,当牡蛎壳粉的质量含量为1%时,复合材料的综合性能最好。

牡蛎壳粉对水产品废水中化学需氧量吸附特性的研究

采用废弃牡蛎壳粉热改性对水产品废水中化学需氧量(CODcr)进行吸附试验,研究了天然牡蛎壳粉、热改性400,850℃条件下牡蛎壳粉用量、温度、pH值、振荡时间对牡蛎壳粉吸附水产品废水中的CODcr影响。同时,以热改性850℃牡蛎壳粉为研究对象进行正交试验。结果表明,牡蛎壳粉对CODcr的最佳吸附条件为牡蛎壳用量1.5 g,温度35℃,pH值8,振荡时间30 min。在此条件下,牡蛎壳粉对废水中CODcr的吸附率可达到72.52%。影响牡蛎壳粉对水产品废水中CODcr的吸附的因素依次是牡蛎壳粉用量、温度、pH值、振荡时间,热改性850℃牡蛎壳粉可用于水产品废水处理。

不同温度胁迫条件下太平洋牡蛎挥发性化合物的变化

为探究温度胁迫后太平洋牡蛎挥发性成分的变化,该研究采用感官评定、气相色谱-离子迁移谱(Gas Chromatography-Ion Mobility Spectroscopy,GC-IMS)、气相色谱-质谱联用(Gas Chromatography-Mass Spectrometer,GC-MS)结合多元统计分析的方法,对不同温度胁迫条件(12、22、32℃)的太平洋牡蛎挥发性成分进行了检测,同时测定了其存活率以及脂肪酸含量的变化。结果显示,胁迫6 d后,低温12℃组的存活率达到97.90%,n-3型多不饱和脂肪酸(Polyunsaturated Fatty Acid,PUFA)含量升高。感官评定、GC-IMS以及GC-MS结果显示辛醛等鱼腥味醛类成分含量下降,而呈紫罗兰气味的(E,Z)-2,6-壬二烯醛升至12.15%,提供了愉悦的气味。高温32℃胁迫后存活率降至26.00%,n-3 PUFA含量下降从46.07%下降至39.59%,同时饱和醛等腥味醛类含量显著上升,加重了太平洋牡蛎的腥味,导致牡蛎的品质严重下降。最后通过统计分析筛选6种关键成分:己醛、辛醛、(E,Z)-2,6-壬二烯醛、(E)-2-壬烯醛、(E,E)-2,4-庚二烯醛以及3-辛酮。温度对太平洋牡蛎的存活率、n-3 PUFA含量及挥发性成分有较大影响,该研究为提升太平洋牡蛎品质提供了有益参考。

牡蛎礁生境:海岸带可持续发展的潜在碳汇

牡蛎礁生境是指由聚集的牡蛎和其他生物及环境堆积形成的复合生态系统,其固碳和储碳潜力巨大,在海岸带生态系统中发挥着重要的作用。然而,目前对牡蛎礁生境碳源与汇的认识仍存在不足,主要在于牡蛎钙化和呼吸作用都释放CO_(2),而碳源与汇的评估忽视了钙化、同化和沉积过程带来的整体碳汇价值及牡蛎礁生态系统功能带来的碳汇效应。因此,有必要重新认识牡蛎礁生境的碳汇价值。一方面,牡蛎礁生境的碳源和碳汇需要从牡蛎礁自身的整体碳循环中进行评估,包括牡蛎礁系统中的沉积、钙化、呼吸作用及侵蚀、再悬浮和再矿化作用;另一方面,牡蛎礁生态系统服务引起的碳汇效应需从牡蛎礁的生态系统服务价值角度进行评估,将生态系统服务价值及碳价值进行关联,从而纳入碳汇核算体系。从实现海岸带可持续增汇角度出发,综述了牡蛎礁生境中碳的源与汇;阐述了容易被人们忽视的微生物在牡蛎礁生境碳汇中的作用;以保护和生态修复为目的,进一步提出可实现牡蛎礁生境最大潜在碳汇的策略,以期为实现海洋负排放及践行“国家双碳战略”提供理论和技术支撑。