岭南垛基果林湿地土壤碳组分特征

岭南垛基果林湿地是珠三角地区典型的湿地类型之一,其对土壤碳汇的贡献值得关注。为探讨果林种植类型对土壤有机碳的影响,对广州垛基果林湿地内种植黄皮(Clausenalansium)(HP),龙眼(Dimocarpuslongan)(LY)、杨桃(Averrhoa carambola)(YT),龙眼和黄皮间种(LH),杨桃、龙眼和黄皮间种(YLH)共5种种植类型下的表层(0～20 cm)土壤碳组分进行研究。结果表明,不同的植被类型对土壤的总有机碳(SOC)、可溶性有机碳(DOC)、微生物生物量碳(MBC)、易氧化有机碳(ROC)、惰性碳(NLC)含量都有影响,LY的SOC含量最高(22.6 g/kg),显著高于YLH (P<0.05),且NLC含量显著高于LH和YLH (P<0.05)。NLC含量与土壤养分呈正相关,与土壤容重呈负相关。YT的MBC含量显著高于LY、HP、LH (P<0.05),且MBC/SOC显著高于HP、LY(P<0.05)。YLH模式下,土壤DOC含量和DOC/SOC显著高于其他植被类型(P<0.05)。LH的ROC/SOC显著高于HP和L...     

高砷含水层参与腐殖酸-铁矿物转化的关键微生物群落及其对砷迁移转化的影响

【目的】探究不同腐殖酸浓度下参与含砷水铁矿转化的微生物类群组成和丰度变化及对砷释放的影响,预测原位高砷含水层中功能微生物群参与有机质—含砷铁矿物转化过程对砷转化释放的作用。【方法】对河套平原高砷地下水和同深度高砷沉积物中的铁还原功能群落进行富集培养,构建室内厌氧微宇宙体系,将富集菌群分别加入到实验室条件下合成的不同浓度腐殖酸(0、1.5、7、14 mg C/L)-含砷水铁矿体系中,通过体系中砷、铁形态及浓度的变化分析,结合高通量测序技术、X-射线衍射(X-ray diffractometer, XRD),探究不同条件下砷的释放固定和群落的演替。【结果】高砷地下水组(G组)和沉积物组(S组)富集得到的铁还原功能群落具有明显差异,G组中以Aeromonadaceae为特殊优势菌群,而S组中以Shewanellaceae为特殊优势菌群。微宇宙实验结果显示,S组的铁还原量相对较高且速率较快;G组与S组中液相砷形态存在明显差异,整个培养期内G组均以As(Ⅴ)为主,而S组中前期以As(Ⅴ)为主,当反应到达20 d时液相As(Ⅲ)高达3.4μmol/L,推测此时具有砷还原功能的群落占优势地位。当反应...     

微生物有机酸转运蛋白的研究进展

转运蛋白是一类膜蛋白,可介导生物膜内外化学物质的跨膜转运及信号交换。有机酸转运蛋白在微生物有机酸代谢的跨膜转运过程中发挥重要作用,根据转运蛋白有机酸转运的方向不同可以分为摄取转运蛋白和外排转运蛋白。在微生物代谢中,有些有机酸可以作为能源直接参与体内代谢,有些是能量转换过程中的重要中间产物;摄取转运蛋白的过表达,可以促进微生物细胞获取能源物质,高效的生产目标产物;有机酸摄取转运蛋白敲除或外排转运蛋白表达,有利于底盘细胞外排更多目标产物,进而促进有机酸的生物合成。研究有机酸转运蛋白的结构和功能,有助于解析微生物细胞有机酸生物合成及利用的机制,对于提高工业微生物对有机酸的利用及生物合成具有重要作用。本文综述了微生物有机酸转运蛋白分类和结构、转运方式和转运功能等方面,重点综述了转运蛋白在有机酸生产中的应用,为工业微生物有机酸的高效生物合成及未来发展提供参考。     

硫酸盐对淡水养殖池塘表层底泥微生物的影响

硫酸盐引起的生态学效应已得到了越来越多的关注,但目前关于硫酸盐对养殖池塘底泥微生物的影响还知之甚少。【目的】探究不同浓度硫酸盐对养殖池塘底泥微生物的影响规律及可能的机制。【方法】本研究利用采集自养殖池塘的底泥和表层水构建了试验系统,研究了加入约0 mg/L （对照组）、30 mg/L （T1处理组）、150 mg/L （T2处理组）、500 mg/L （T3处理组） Na₂SO₄后表层底泥微生物的丰度、多样性、组成和共生网络的变化规律,并分析了环境影响因素。【结果】孵育第30天前,各实验组底泥微生物变化不大;但到第50天时,T2和T3处理组微生物丰度和多样性相比对照组均明显下降。相比其他实验组,T1处理组酸杆菌门（Acidobacteriota）、拟杆菌门（Bacteroidota）相对丰度出现显著升高（P<0.05）,T3处理组变形菌门（Proteobacteria）和放线菌门（Actinobacteriota）相对丰度出现显著升高（P<0.05）。与对照组相比,T1处理组增加了较多差异类群（62种）,而T3处理组差异类群大量减少（45种）。共生网络图分析显示硫酸盐浓度的增加引起了底泥微生物网络复杂性的增加,说明微生物群落可能通过自身的调节来响应硫酸盐引起的环境改变。冗余分析（redundant analysis,RDA）和相关性分析揭示底泥总有机碳、总氮和氧化还原电位是影响底泥微生物的主要环境因素,提示底泥微生物可能受到硫酸盐和有机质作用的影响。【结论】较长时间的高浓度硫酸盐会对池塘底泥微生物群落造成重要影响,微生物群落自身的转变和硫酸盐引起的有机质分解改变可能是造成微生物群落变化的关键因素。     

Behaviour of suspended and sedimentary organic matter in the deltaic areas of the Gulf of Lions (Mediterranean Sea)

The behaviour of organic matter has been approached in two fluvio-marine areas of the Gulf of Lions in the Northwestern Mediterranean Sea: deltas of the Rhône and Têt rivers. Elemental analysis, pyrolysis-gas chromatography-mass spectrometry (main classes of organic compounds) and high performance liquid chromatography (phenolic compounds) enabled to show the fractioning processes and the differentiation of water layers from the river mouth to the open sea. Transitory horizontal and vertical geochemical gradients appeared in the water column. They were more marked in surficial sediments. They underlined the effects of the river inputs which were characterized by high phenol contents. The increase of the marine character towards the open sea was shown by increasing nitrogen-containing compounds. In the Rhône delta, the distribution of the suspended material and organic compounds emphasized the occurrence of a multi-layered water system. In the surficial layers the suspended organic matter was in a little degraded state. On the contrary, the bottom nepheloid contained altered organo-mineral complexes enriched in resistant organic compounds. In the deeper areas of the Lacaze-Duthiers Canyon, in front of the Têt prodelta, the abundance of phytoplanktonic material in the euphotic zone was emphasized by the increase of both nitrogen-containing compounds and aminosugars. In the deeper layers, the suspended material transported by advective currents showed a detrital characteri.e. enriched in clays and in degraded organic matter. The observations carried out in the Rhône delta, the Têt prodelta and the Lacaze-Duthiers Canyon underlined the importance of the general transfer system of suspended material from East to West enhanced by the Liguro-Provençal current.     

The role of mineral compounds and chemical conditions in the binding of phosphate in the Ems estuary

In the Ems estuary the gradients in dissolved phosphorus and iron are non-conservative and opposite. The relations between different mineral compounds, environmental conditions and phosphate concentrations were studied, in an attempt to explain this. Laboratory experiments on water samples from the reaches with high concentrations of phosphate and of suspended matter revealed a low concentration of calcite-bound phosphorus in the middle reaches of the estuary (only 0.07%). Therefore, it is concluded that calcite possibly plays only a modest role in phosphate distribution in the Ems estuary. Further experiments revealed that nearly 70% of the particulate inorganic phosphorus is iron-bound. It is demonstrated that organic coatings on minerals inhibit phosphate release at a low redox potential. Moreover, the organic matter itself contained c. 20% of particulate phosphorus. Approximately 10% of the particulate phosphorus may be associated with clay minerals. It is concluded that in addition to biological processes, the phosphorus associated with ironoxyhydroxides may be crucial for the seasonal variation of the phosphate concentrations in the water.     

利用酵母菌生产有机酸的研究进展

有机酸是含有一种或多种低分子量酸性基团(如羧基、磺酸基)的可生物合成的有机化合物,广泛应用于食品、农业、医药、生物基材料工业等领域。酵母菌具有生物安全、抗逆性强、底物谱广泛、方便遗传改造,以及大规模培养技术成熟等独特优点,因此利用酵母菌生产有机酸的研究日益受到国内外学者的关注。目前利用酵母生产有机酸还存在浓度低、副产物多,以及发酵效率低等缺陷。随着酵母菌代谢工程和合成生物学技术的发展,利用酵母菌生产有机酸取得了快速进展。本文总结了利用酵母合成11种有机酸的研究,包括内源和异源合成的大宗羧酸和高价值有机酸,并对该领域的未来研究方向进行了展望。     

Growth and nutrition of birch seedlings in relation to potassium supply rate

Summary Growth of hydroponically cultivated birch seedlings (Betula pendula Roth.) at sub- and supra-optimum potassium supply rates was investigated. Potassium was supplied either as a relative addition rate (r _k = 5, 10, 15 and 20% increase day^-1) or as fixed concentrations (0.2, 3, 6, 12 and 15 mM) in the culture solution. After an acclimation period the growth rate of the seedlings in the suboptimum treatments reached values close to the treatment variable, the relative rate of K-addition. Deficiency symptoms, in the form of chlorosis and necroses along the leaf margins, developed initially in all suboptimum treatments, but very few new symptoms appeared once the seedlings had reached the phase of steady-state nutrition and growth. At supra-optimum K-supply levels, i.e. at 0.2–15 mM K in the culture solution, no symptoms of deficiency or toxicity developed, and the relative growth rate of the seedlings remained maximum. The relative growth rate of the seedlings was linearly related to the plant K-status for K contents ranging from 0.2 to 1.0% of dry weight (DW). At higher internal K-concentrations, 1.0–3.0% DW, no further increase in relative growth rate was achieved. A shortage of K resulted in a decrease in the net assimilation rate. This effect was counterbalanced by the absence of shift in he leaf weight ratio as well as by the production of relatively thin leaves. The fraction of dry matter allocated to roots decreased in K-limited plants, as did the leaf contents of soluble carbohydrates and starch.     

有机框架材料在多肽富集的应用

生物医药领域近年来发展迅猛,多肽类药物因其生物学活性高、毒性小、生物相容性好等优势,在肿瘤治疗、细胞活性模拟、抗体检测等领域展开广泛应用,多肽的检测分析也成为研究的一大热点。传统的色谱法、溶剂沉淀法、离心超滤法和固相萃取法对多肽能够展现富集效果,但富集的效率往往不够理想。近年来,以有机框架材料为代表的纳米材料,在气体吸附、荧光、传感和催化等领域展开了广泛应用。有机框架材料凭借着独特的结构尺寸,成为了一类理想的生物吸附剂。由于其具有表面可修饰性,能够大大提高对多肽的富集效率。本文着重介绍近5年来金属-有机框架材料（metalorganic frameworks,MOFs）和共价-有机框架（covalent-organic frameworks,COFs）在多肽富集中的应用。     

沙地云杉苗期生长与干物质生产关系的研究

本文用不同_的模型定量地研究了沙地云杉苗期的生长规律、季节动态及不同生长时期干物质在各器官之间的分配规律。1)1年生幼苗一直保持较高的生长速度,根生长尤为迅速。5年生幼苗在接近生长上限时,增长越来越慢。2)根、茎、叶干物质的生产符合理查德模型;根、茎、叶干重与全株干重之百分比表现出不同的变化趋势,反映了于物质在各器官中的分配规律。3)不同年度各器官的干重变化反映了由于自疏造成的叶的脱落和部分枝的脱落情况。4)各模型的相关系数几乎都达到了极显著的水平。