珠江口城市段近岸表层水体浮游细菌分离方法比较

为了更好地分离珠江口未/难培养的浮游细菌,本研究以珠江河口三个样点的水体为研究对象,同时采用了纯培养和免培养的方法,对不同培养基的分离效果进行了探索。在纯培养实验中,本研究选择了7种不同的分离培养基,共分离获得153株菌;同时,将扩增子分析结果作为分离效果的参考,所有环境样品中共包含3 553个操作分类单元（operational taxonomic units,OTUs）。对三个样点微生物类群的多样性进行比较,纯培养结果显示珠江口下游珠海样点多样性最高,其次为中大和虎门样点;免培养则显示虎门样点多样性最高;对比7种不同的分离培养基,Z7（R₂A）培养基的分离效果最好,分离菌株数和分离类群的α多样性最高,Z1（改良ISP 2）次之;主坐标分析结合韦恩图的结果表明相比其余的培养基,Z1和Z7培养基分离获得的菌群兼具普遍性和特异性,进一步证明了这两种培养基的分离效果较佳;冗余分析结果表明K₂HPO₄、酵母粉、可溶性淀粉、MgSO₄·7H₂O、麦芽膏和葡萄糖与特定类群的分离有相关关系,其中K₂HPO₄的影响最为显著（P<0.05）。本文通过7种不同培养基对河口微生物分离效果的探究,有助于我们在研究未知微生物的营养特性时,选择成分和组成更合理的培养基来提升河口微生物纯培养的分离效率。     

Coassemble dopamine and GHK tripeptide into fluorescent nanoparticles for pH sensing

Fluorescent nanostructures have been widely applied to biomedical researches and clinical diagnosis such as biolabeling/imaging/sensing and have even acted as therapy reagents. Peptide‐based fluorescent nanostructures attract recent interest from biomedical researchers. Inspired by the natural existence of GHK‐Cu complex with a growth factor‐like effect in human blood, here we have developed a novel approach for designing nanosensors through the co‐assembling of two kinds of biomolecules. By making best use of both π‐π stacking between carbon rings and the easy‐oxidation property of an important transmitter molecule, dopamine (DA), we successfully built up a supersensitive and robust fluorescent pH nanosensor by co‐assembling oxidized DA (DA_ox) with a tripeptide GHK. The GHK‐DA_ox nanostructures have a quantum yield of 20.82%, which might be the brightest one among all the current co‐assembling structures merely through unmodified biomolecules. We envision this approach could open a new avenue for not only hybrid nanostructure construction, but also may inspire the bioengineering of in vivo luminescent probes.     

两株芽孢杆菌在苎麻纤维复合脱胶中的应用

【背景】苎麻纤维细长、强韧、洁白、有光泽,被誉为"天然纤维之王",应用广泛。但其被以半纤维素和果胶为主要成分的胶质所包裹,脱胶是生产精干麻工艺的核心工序。利用单一菌株脱胶,往往因其脱胶酶系不全,存在胶质去除率低的问题,导致后期仍需要大量的碱和漂白剂处理。【目的】丰富苎麻脱胶过程中关键酶系,从而提高苎麻胶质去除率,并降低脱胶后期化学试剂的用量,推进苎麻生物脱胶的工艺应用。【方法】选用2株芽孢杆菌HG-9 (高果胶酶和甘露聚糖酶)和HG-25(高木聚糖酶)建立了复合微生物脱胶技术,并对其进行了优化。【结果】当2株菌接种量均为6%,水料比16:1,初始pH值5.9,在温度37.6°C下脱胶处理14 h时脱胶效果最佳,与菌株HG-9单独脱胶相比,脱胶时间减少2 h,胶质去除率、半纤维素去除率和木质素去除率分别提高9.32%、21.24%和17.93%,次氯酸钠用量减少20%。通过电子显微镜分析其形貌特征发现,混合脱胶获得的纤维表面更加平滑,无明显扭曲和损伤且纤维分散度较高。【结论】通过复合微生物协同作用,丰富脱胶过程中关键酶系,提高了苎麻纤维胶质去除率,缩短了脱胶时间,而且减少了脱胶后期漂白剂的用量,为苎麻生物脱胶工业化应用的进一步发展提供了指导。     

白化和黄化茶树品种绿茶游离氨基酸、儿茶素类及咖啡碱差异分析

为探究以白化和黄化茶树品种鲜叶为原料制成的绿茶滋味品质和代谢物差异,对广德市6个白化品种绿茶(奶白茶)和14个黄化品种绿茶(黄金芽茶)进行感官审评和代谢物分析。结果表明,奶白茶滋味鲜爽而收敛性略弱;黄金芽茶滋味收敛性强而鲜度低于奶白茶。游离氨基酸总量以及呈现鲜味、甜味的游离氨基酸在奶白茶中的含量显著高于黄金芽茶,而贡献收敛性的儿茶素类化合物和没食子酸含量以及呈现苦味的咖啡碱含量在奶白茶中显著低于黄金芽茶。偏最小二乘法判别分析(PLS-DA)表明导致两种绿茶滋味差异的标志性化合物有7种,分别是茶氨酸、精氨酸、谷氨酸、天冬氨酸、表没食子儿茶素没食子酸酯(EGCG)、表儿茶素没食子酸酯和咖啡碱。味觉活性值(Dot)最高的EGCG在黄金芽茶中的呈味贡献显著高于奶白茶。因此,游离氨基酸、儿茶素类化合物、没食子酸和咖啡碱含量差异导致白化和黄化茶树品种绿茶滋味不同。     

Mechanisms of soil bacterial and fungal community assembly differ among and within islands

The study of islands has made substantial contributions to the development of evolutionary and ecological theory. However, we know little about microbial community assembly on islands. Using soil microbial data collected from 29 lake islands and nearby mainland, we examined the assembly mechanisms of soil bacterial and fungal communities among and within islands. We found that deterministic processes, especially homogeneous selection, tended to be more important in shaping the assembly of soil bacterial communities among islands, while stochastic processes tended to be more important within islands. Moreover, increasing island area increased the importance of homogeneous selection, but reduced the importance of variable selection, for soil bacterial community assembly within islands. By contrast, stochastic processes tended to dominate soil fungal community assembly both among and within islands, with dispersal limitation playing a more important role within than among islands. Our results highlight the scale- and taxon-dependence of insular soil microbial community assembly, suggesting that spatial scale should be explicitly considered when evaluating the influences of habitat fragmentation on soil microbial communities.     

Deinococcus aestuarii sp. nov. and Deinococcus aquaedulcis sp. nov., two novel resistant bacteria isolated from pearl river estuary

Two novel species of the genus Deinococcus, designated SYSU M49105^T and SYSU M42101^T, were isolated from freshwater samples of the Pearl River estuary in Guangdong, China. Phylogenetic analysis using 16S rRNA gene sequence indicated that strains SYSU M49105^T and SYSU M42101^T showed the highest sequence similarities to Deinococcus aetherius JCM 11751 ^T (93.6%) and Deinococcus multiflagellatus NBRC 112888 ^T (97.3%), respectively. Cells of both strains were Gram-staining positive, aerobic, coccus-shaped, oxidase-negative and non-motile. The cell wall contained meso-diaminopimelic acid as their diagnostic diamino acid. MK-8 was the predominant respiratory quinone for both strains. The polar lipid profile of SYSU M49105^T contained two unidentified phosphoglycolipids, nine unidentified glycolipids, and five unidentified polar lipids. SYSU M42101^T had one unidentified phosphoglycolipid, nine unidentified glycolipids, one unidentified aminophospholipid and four unidentified polar lipids. The major fatty acids of strains SYSU M49105^T and SYSU M42101^T were summed feature 3 (C_16:1 ω7c and/ or C_16:1 ω6c) and C_16:0. The G?+?C contents of the novel isolates based on genomic DNAs were 69.6% and 67.4%, respectively. On the basis of phenotypic, genotypic and phylogenetic data, strains SYSU M49105^T and SYSU M42101^T should be considered to represent two novel species in the genus Deinococcus, for which the names Deinococcus aestuarii sp. nov. and Deinococcus aquaedulcis sp. nov. were proposed with the type strains SYSU M49105^T (=?KCTC 43258 ^T?=?CGMCC 1.18609 ^T) and SYSU M42101^T (=?KCTC 43257 ^T?=?CGMCC 1.18614 ^T), respectively.

     

不同白化期的‘黄山白茶’代谢物差异分析

‘黄山白茶1号’是温度敏感型白化茶树品种,由其鲜叶加工的绿茶,即‘黄山白茶’,具有清香持久、滋味鲜爽等特征。为探究不同白化时期加工绿茶的香气和滋味差异,分析了绿茶中挥发性代谢物、儿茶素、咖啡碱和游离氨基酸含量的变化。结果表明,3个白化时期的‘黄山白茶’在香气和滋味上存在差异。气相质谱（GC-MS）分析表明,共有29个高丰度挥发性化合物被鉴定;主成分分析（PCA）显示芳樟醇、顺-己酸-3-己烯酯、香叶醇、顺-3-己烯醇、（Z）-丁酸-3-己烯酯可能是导致3类绿茶香气存在差异的标志性化合物。滋味成分分析表明儿茶素类物质在白化早期绿茶中含量最低;在白化中期绿茶中略有增加但不显著,而在白化后期绿茶中则显著增加;咖啡碱在3类绿茶中无显著差异;游离氨基酸在白化早期绿茶中含量最高,为干质量的4.4%,而在白化后期绿茶中只占干质量的1.3%。因此,不同时期的‘黄山白茶1号’嫩梢中的代谢物积累存在差异,使得加工的绿茶风味不同。     

High‐Performance Suspended Particle Devices Based on Copper‐Reduced Graphene Oxide Core–Shell Nanowire Electrodes

Smart windows are one of the key components of so‐called “green” buildings. These windows are based on an actively switchable electro‐optic material that is sandwiched between two transparent electrodes. Although great progress has been made in identifying the optimal materials for such active windows, there is still a great need to improve their key elements, especially the performance of the transparent electrodes. Here, a new suspended particle device (SPD), holding a great potential for smart window applications, which is built upon copper‐reduced graphene oxide (Cu‐rGO) core–shell nanowire (NW) films as a transparent conductive electrode is reported. With the wrapping of rGO, the Cu NW electrodes demonstrate both high optical transparency and electrical conductivity, as well as significantly improved stability under various testing conditions. The novel sandwich‐structured SPDs, based on these electrodes, show a large change in their optical transmittance (42%) between “on” and “off” states, impressively fast switching time and superior stability. These high performances are comparable to those of the SPDs based on indium tin oxide electrodes. These promising results pave the way for the electrodes to be an integral part of a variety of optoelectronic devices, including energy‐friendly and flexible electronics.     

Assessment of Dynamic Cerebral Autoregulation in Patients with Basilar Artery Stenosis

Background and Aims

Previous studies have shown impaired cerebral autoregulation (CA) in carotid and middle cerebral artery (MCA) stenosis/occlusion. Little is known about CA in patients with basilar artery (BA) stenosis. We therefore investigated dynamic CA patterns in BA stenosis using transfer function analysis (TFA).

Methods

We measured spontaneous oscillations of blood flow velocity (CBFV) in the right posterior cerebral artery (PCA), and left MCA and mean arterial pressure (ABP) continuously in 25 patients with BA stenosis (moderate n=16 with 50-69% occlusion and severe n=9 with ≥70% occlusion) and 22 healthy volunteers in supine position during 6 circles per minute deep breath. Analysis was based on the ‘black-box’ model of transfer function deriving phase and gain in both PCA and MCA.

Results

Though changes of phase shift and gain between the patients and healthy controls were observed in MCA, the differences are however not significant. Phase shift in PCA was significantly decreased in severe stenosis when comparing with healthy controls and moderate stenosis (4.2±34.2° VS 41.1±40.4°, 4.2±34.2° VS 34.2±27.2°, both p<0.05), whilst the gain in PCA is increased for moderate BA stenosis and decreased for severe BA stenosis. Furthermore, we found that phase shift were almost abolished in patients with ischemic stroke who developed unfavorable clinical outcome (mRs>2) on the 90 days after stroke onset.

Conclusion

Dynamic CA in PCA reduces in patients with severe BA stenosis and those with ischemic stroke who present poor outcome in 90 days after stroke onset. Phase shift might be a sensitive index prompting impaired CA in posterior circulation.