西藏扎布耶盐碱湖细菌的多样性与分离菌株的生长特性

【背景】扎布耶湖位于青藏高原地区,是以水体中富含高浓度CO₃²⁻、HCO₃⁻和Na⁺为显著特性的盐碱湖,因其地理位置高寒、高海拔,人迹罕至,涉及该盐湖微生物的研究相对较少。【目的】系统探究湖水中细菌多样性和菌种资源等,发掘可利用的潜在菌种。【方法】采用Illumina测序16S rRNA基因V3−V4区分析扎布耶湖细菌的群落结构组成、物种多样性特征;采用纯培养筛选分离可培养细菌,明确分离菌株分类学地位、生长特性及产酸能力,同时测定分离菌株四氢嘧啶(ectoine)、吲哚乙酸(3-indoleacetic acid, IAA)和胞外聚合物(extracellular polymeric substances, EPS)的积聚量。【结果】Illumina测序明确分类地位的细菌有21门44纲86目583属,其中优势门类群是变形菌门(Proteobacteria, 25.11%−67.60%)、拟杆菌门(Bacteroidetes, 4.84%−35.02%)和厚壁菌门(Firmicutes, 1.24%−11.01%),优势属类群是克雷伯氏菌属(Klebsiella, 0.01%−9.53%)、盐单胞菌属(Halomonas, 0.54%−8.75%)、芽单胞菌属(Gemmatimonas, 2.39%−6.00%)和腈基降解菌属(Nitriliruptor, 1.27%−6.26%)。纯培养法筛选获得嗜盐碱菌38株,其中芽孢杆菌属(Bacillus) 23株(60.53%)和盐单胞菌属(Halomonas) 10株(26.32%),菌株均具有耐盐碱和产酸能力(19.80%−29.68%)。大多数菌株能积聚四氢嘧啶、IAA和EPS,产量范围分别为1.36−175.59、0.27−8.69和0.02−0.22 g/g。【结论】扎布耶湖细菌群落结构与其他地区盐碱湖相似,但存在大量未明确分类学地位的细菌,分离菌株多具有耐盐碱及产酸特性。此外,还发现4株高效生产四氢嘧啶、3株生产吲哚乙酸和3株生产胞外聚合物的潜力菌株,为扎布耶盐湖微生物资源的开发利用奠定了基础。     

鼠李糖乳杆菌碱性磷酸酶的提取条件优化及其降解有机磷农药作用

【背景】我国作为农业大国,对农药的大量使用是不可避免的,但是农药的超范围使用、超标及高检出率对于环境的污染与人体健康的威胁日趋严重。【目的】碱性磷酸酶(alkaline phosphatase,ALP)对有机磷农药具有积极的降解作用,因此,本文对鼠李糖乳杆菌(Lactobacillus rhamnosus) Z23(LGG Z23)所产碱性磷酸酶的提取条件进行优化,并研究其对有机磷农药的降解作用。【方法】使用单因素试验和正交试验优化ALP的提取条件;使用对硝基苯酚法测定酶活力;使用分级沉淀和层析法提纯ALP;使用乙酰胆碱酯酶抑制法测定ALP对有机磷农药的降解率。【结果】LGG Z23所产ALP的最优提取条件为：细胞破碎时间15 min,破碎功率450 W,料液比(质量体积比)1:6,提取液pH 10.0,此条件下酶活力为(4.95±0.26) U/mL,比优化前提高2.11倍;对6种有机磷农药的降解率效果为敌敌畏(95.79%±0.01%)>甲基对硫磷(90.69%±0.03%)>毒死蜱(88.90%±0.02%)>敌百虫(86.07%±0.03%)>马拉硫磷(85.31%±0.02%)>乐果(83.18%±0.03%),其中对敌敌畏和甲基对硫磷的降解效果最好,可达90%以上,并且降解作用差异显著(P<0.05)。【结论】本研究为LGG Z23所产ALP的应用研究提供了理论依据和实验数据。     

北桑寄生产黄酮内生菌的分离鉴定及其抗氧化和抑菌活性评价

【背景】北桑寄生(Loranthus tanakae)植物中黄酮类化合物成分含量较高,生物活性较好。由于植物资源短缺,导致其生物活性成分的研究受限。【目的】从北桑寄生中分离、筛选和鉴定产黄酮类化合物的内生菌,并评估其体外抗氧化和抑菌活性。【方法】以北桑寄生枝条为研究对象分离内生菌,通过显色反应和薄层色谱法(thin-layer chromatography,TLC)筛选产黄酮类化合物的内生菌,并采用NaNO₂-Al (NO₃)₃比色法测定其总黄酮含量。利用清除自由基和抑菌的体外实验来初步评估产黄酮内生菌的生物活性。【结果】共筛选出4株产黄酮内生菌,其中3株为内生真菌,1株为内生细菌,通过形态学和分子生物学方法将其分别鉴定为Botryosphaeria sp.(ZC020)、Phoma sp.(ZZ105)、Nemania sp.(ZS042)和Pseudomonas sp.(ZC026)。4株菌中ZC020和ZS042的总黄酮含量较高,分别为(44.58±0.72) mg/L和(31.98±0.18) mg/L (P<0.05,n=3),并且ZS042可产生与北桑寄生植物相同类型的黄酮类化合物。ZC026和ZS042表现出优异的抗氧化活性,其1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)和2,2''-联氮-二(3-乙基苯并噻唑啉-6-磺酸)二铵盐[2,2''-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt,ABTS]自由基清除率分别为72.85%±0.66%(ZC026)、57.01%±0.89%(ZS042)和85.36%±0.75%(ZC026)、88.17%±0.15%(ZS042)(P<0.05,n=3)。ZZ105对革兰氏阳性菌和革兰氏阴性菌均有抑制作用。【结论】从北桑寄生枝条中分离出4株产黄酮类化合物的内生菌,其中有一株为内生细菌。这项工作为北桑寄生黄酮类化合物的生产提供了新的资源,也为其他珍稀药用植物和材料的开发和保护提供了参考。     

接种AMF和DSE对蛋白桑提质增产效应的影响

【目的】探究丛枝菌根真菌(arbuscular mycorrhiza fungi,AMF)和深色有隔内生真菌(dark septate endophyte,DSE)对蛋白桑(Morus alba)产量及品质的影响。【方法】采用盆栽试验,以丛枝菌根真菌和深色有隔内生真菌为微生物处理菌剂,通过设置单接种DSE、单接种AMF和联合接种DSE+AMF 3种不同微生物组合研究对蛋白桑生长、产量和品质等影响,探索微生物菌剂对生态饲料作物蛋白桑的经济潜力。【结果】与未接菌处理(CK)相比,3种接菌处理均能显著促进蛋白桑地上部生长,提高地上部生物量,增加幅度为156.4%‒196.6%;接菌微生物提高了蛋白桑的光合速率,增加了植物叶片氮、磷、钾的累积,提高蛋白桑的产量。接种微生物会使蛋白桑叶粗蛋白含量提升,降低饲料纤维营养价值,从而综合改善蛋白桑品质。微生物处理能够显著增加蛋白桑的叶茎比,提升了蛋白桑叶片的比例,优化生长结构,不同微生物处理对蛋白桑叶片各饲用品质指标的影响较其相应茎部更为明显,可以根据桑叶和茎秆的蛋白含量进行合理搭配获得饲料不同品级,从整体水平上提升蛋白桑地上部植株的饲用品质。接种微生物均对蛋白桑饲用品质等级得到极大提升,显著降低了酸性洗涤纤维和中性洗涤纤维含量,降低幅度分别为18.4%‒34.6%和41.0%‒45.4%;接菌处理各蛋白桑的相对饲用价值范围在220.0‒241.5,显著提高0.8‒1.0倍,且维生素C含量、含糖量和生物碱含量等均有增加。【结论】采用主成分分析方法,按照对蛋白桑产量和品质的综合影响大小的贡献排序,依次为：AMF+DSE>DSE>AMF>CK,DSE可作为采煤沉陷区生物修复中经济作物蛋白桑的优选微生物菌剂,能促进蛋白桑的产量并提升品质。     

山西省草地早熟禾白粉菌分离株BGP(TG)的鉴定及致病力分析

【背景】草地早熟禾(Poa pratensis)是一种被广泛使用的兼具观赏性和设施性的冷季型草坪草，白粉病的发生严重降低了草地早熟禾的质量和使用年限。【目的】对山西农业大学温室草地早熟禾白粉病病原物进行分离、纯化、鉴定和致病力分析，为草地早熟禾白粉病的防治提供理论依据。【方法】采用形态特征观察、核糖体内源转录间隔区(ribosomal DNA internally transcribed spacer, rDNA-ITS)序列分析进行分离株BGP(TG)的鉴定；通过分生孢子密集抖落接种法测定BGP(TG)对23份草地早熟禾材料的致病力。【结果】草地早熟禾白粉菌分离株BGP(TG)分生孢子串生、无色、椭圆形，长和宽分别为(23.31−34.67) µm和(11.33−15.77) µm，成熟吸器为指状；rDNA-ITS序列分子发育分析结果表明分离株BGP(TG)与禾布氏白粉菌早熟禾专化型(Blumeria graminis f. sp. poae)聚于同一分支；BGP(TG)对23份草地早熟禾的致病力测定结果显示，白粉病发病率为49.47%−77.72%，病情指数为14.41−53.12；仅‘太行’草地早熟禾对BGP(TG)表现为中抗，‘应县’ ‘黑杰克’和‘浑源’草地早熟禾表现为中感，‘探险家’和‘奖品’草地早熟禾表现为极感，其余17个品种表现为高感，占比达73.91%。【结论】山西省草地早熟禾白粉菌分离株BGP(TG)的致病力较强，进一步挖掘‘太行’草地早熟禾的抗白粉病基因，对草地早熟禾抗白粉病育种工作具有重要意义。     

镉胁迫下硫素对嗜鱼外瓶霉生长、矿质元素与镉含量的影响

镉(100 mg/L)胁迫下,研究不同浓度硫素(硫离子)对深色有隔内生真菌(Dark septate endophyte,DSE)——嗜鱼外瓶霉(Exophiala pinsciphila)菌株生长、矿质元素(钙、镁、氮、磷、硫)与镉含量的影响。结果表明:在100 mg/L镉胁迫下,低浓度(0.06和0.30 mmol/L)和高浓度(3.60和6.60 mmol/L)硫素处理均显著降低菌丝干质量(P0.05),而对培养液孢子数和p H值无影响。培养液硫浓度(0.06,0.30,0.60,3.60和6.60 mmol/L)显著影响菌丝矿质元素和镉含量,其中钙、磷、硫和镉含量在高浓度(3.60和6.60 mmol/L)处理下显著增加,在低浓度(0.06和0.30 mmol/L)处理下却显著下降;低浓度处理显著增加菌丝氮含量。菌丝镉含量(0.53～3.55 g/kg)和培养液硫浓度与菌丝矿质营养元素磷、硫、钙呈极显著正相关。镉胁迫下,外源添加高浓度的硫会降低菌株镉耐性,抑制DSE的生长和对矿质元素的吸收利用,而正常浓度的硫添加有助于菌株生长。     

Detection of potentially myocardial infarction susceptible individuals in Indian population

Zinc (Zn) and copper (Cu) concentrations in hair and urine of patients diagnosed and hospitalized for myocardial infarction (MI patients) and in their descendants (MI descendants) were estimated and compared with their age-matched healthy volunteers with no family history of MI (control group and control descendants). The data revealed approximately twofold higher Zn and twofold lower Cu in the urine of the patients; Zn was lower and Cu was higher in the urine of MI descendants than those of the patients (p<0.001), but Zn in hair and urine was higher and Cu in hair was lower in MI descendants compared with their control counterparts (p<0.001). The data suggested that there was a consistent rise in Zn and fall in Cu reserves in the genetically predisposed subjects (MI descendants) prior to the manifestation of clinical symptoms. Based on this, the data were subjected to logistic regression and a model was obtained to predict the susceptibility to MI (LR-MI), having impact factors values as follows: constant (C), −3.342; impact factor of body mass index, −0.776; impact factor of hair Zn, −2.449; impact factor of urine Zn, +3.441; impact factor of hair Cu, −15.077; impact factor of urine Cu, −24.153. For the equation Y=e ^x (1+e ^x ), the value of x was obtained as follows: −3.342+[BMI (kg/m²) (−0.776)]+[Hair Zn (μmol/g) (−2.449)]+[Urine Zn (μmol/L) (3.441)]+[Hair Cu (μmol/g) (−15.077)]+[Urine Cu (μmol/L) (−24.153)]. On substituting the values of BMI, hair Zn, urine Zn, hair Cu, and urine Cu in x, the response variable Y as zero for healthy controls and 0.99 or 99.9% susceptibility in MI patients were obtained. In between these two extremes, the response variable ranged between 0 and 0.99 or 99.9% susceptibility to MI in their descendants. It is envisaged that the MI patients have an operational component of a genetic disorder of ionic imbalance at a young age that can be exploited in making a prediction of susceptibility to heart stroke in individuals much before its onset and diagnosis in asymptomatic patients, particularly in genetic and epidemiological studies of MI.     

Variations in daytime net carbon and water exchange in a montane shrubland ecosystem in southeast Spain

Carbon and water fluxes in a semiarid shrubland ecosystem located in the southeast of Spain (province of Almería) were measured continuously over one year using the eddy covariance technique. We examined the influence of environmental variables on daytime (photosynthetically active photons, F _P >10 μmol m⁻² s⁻¹) ecosystem gas exchange and tested the ability of an empirical eco-physiological model based on F _P to estimate carbon fluxes over the whole year. The daytime ecosystem fluxes showed strong seasonality. During two solstitial periods, summer with warm temperatures (>15 °C) and sufficient soil moisture (>10 % vol.) and winter with mild temperatures (>5 °C) and high soil moisture contents (>15 % vol.), the photosynthetic rate was higher than the daytime respiration rate and mean daytime CO₂ fluxes were ca. −1.75 and −0.60 μmol m⁻² s⁻¹, respectively. Daytime evapotranspiration fluxes averaged ca. 2.20 and 0.24 mmol m⁻² s⁻¹, respectively. By contrast, in summer and early autumn with warm daytime temperatures (>10 °C) and dry soil (<10 % vol.), and also in mid-winter with near-freezing daytime temperatures the shrubland behaved as a net carbon source (mean daytime CO₂ release of ca. 0.60 and 0.20 μmol m⁻² s⁻¹, respectively). Furthermore, the comparison of water and carbon fluxes over a week in June 2004 and June 2005 suggests that the timing—rather than amount—of spring rainfall may be crucial in determining growing season water and carbon exchange. Due to strongly limiting environmental variables other than F _P, the model applied here failed to describe daytime carbon exchange only as a function of F _P and could not be used over most of the year to fill gaps in the data.     

The effect of benthic sediments on dissolved nutrient concentrations and fluxes

The Ria Formosa is a meso-tidal coastal lagoon experiencing enhanced nutrient concentrations. Assessment of sediment–seawater interaction is essential if nutrient dynamics and the risk of eutrophication are to be fully understood. Pore water concentrations of dissolved inorganic and organic phosphorus, ammonium, nitrate and nitrite were determined in cores from six sites. Changes in nutrients concentrations were measured in intertidal pools on sand and mud between tides. Dissolved inorganic phosphorus (DIP) concentrations (~200 μmol l⁻¹) and effluxes (123 ± 14 μmol m⁻² h⁻¹) were greater from sand than mud (37 ± 10 μmol m⁻² h⁻¹), possibly due to the binding of P with the <63 μm fraction. NH₄⁺ effluxes were high outside the Anc?o Basin (821 ± 106 μmol m⁻² h⁻¹) and were associated with Enteromorpha sp. mats. The greatest NO₃⁻ efflux was from sediments near a salt marsh (170 ± 67 μmol m⁻² h⁻¹). These sediment fluxes of P were not sufficient to account for elevated P concentrations seen by other workers on the ebb tide from the Anc?o Basin. Intertidal pools were sinks for Dissolved Inorganic Nitrogen (DIN) and DIP over the 6 h exposure period. Thus, tidepools may be an important route of nutrients into sediments that enhances the effects of sediments on seawater nutrient concentrations.     

Phytoplankton primary production in a mesotrophic pond in sub-tropical Bangladesh

Annual gross primary productivity in mesotrophic Shahidullah Hall pond (Dhaka, Bangladesh) was 1383.35 g C m⁻² y⁻¹ (arithmetic mean). Daily primary productivity (between 1.6 and 6.8 g C m⁻² d⁻¹ was correlated with chlorophylla, day length and dissolved silica. Chlorophylla related significantly withk, incident light, SRP, alkalinity and conductivity. A negative correlation existed between biomass and rainfall. Productivity, biomass, conductivity, alkalinity, and SRP increased after mid-winter.k, I _k andZ _eu varied according seasonally.P _max related directly with temperature. Seasonal variation of ∝ ^B was 0.0049–0.0258 mg C (mg chla mmol PAR)⁻¹ m⁻². Q₁₀ was 2.12, community respiration 1334.99 g C m⁻² y⁻¹, and the underwater light climate 186.43μE m⁻² s⁻¹.     

丛枝菌根真菌与深色有隔内生真菌对姜瘟病的防效及抗病机理初探

【背景】青枯劳尔氏菌(Ralstonia solanacearum,R.S)引发的姜瘟病是生姜产业发展的瓶颈问题。丛枝菌根真菌(arbuscular mycorrhiza fungi, AMF)与深色有隔内生真菌(dark septate endophytes,DSE)是两类重要的共生微生物。【目的】前期研究发现,AMF与DSE可提高生姜对姜瘟病的抗性,但其抗病机制尚不清楚,极大地限制了利用这两类共生真菌对该病的防治。【方法】在温室条件下做盆栽试验,以生姜组培苗为材料,设立接种AMF、DSE和不接种AMF、DSE的对照(CK)处理,并在上述处理下的植物生长4周后淋入病原菌液,病原菌接种1周后,通过测定菌根侵染率、发病率、叶绿素含量、光合指标、磷(P)含量、防御性酶活性及丙二醛(malondialdehyde, MDA)含量,研究AMF和DSE互作对病原菌侵染后生姜生长和生理生化指标的影响。【结果】AMF和DSE分别使姜瘟病发病率降低了45.27%和52.04%(P<0.05)。AMF+DSE组合处理抑病效果更好,发病率较对照降低60.87%(P<0.05)。AMF、DSE及...     

香菇复配氨基酸培养基优化及其对香菇菌丝生长生理的影响

[背景]L-氨基酸能够提供香菇生长发育的部分养分需求,利用外源添加氨基酸的方式对香菇生长基质进行优化,对于香菇产业的增产提质具有积极的发展意义.[目的]利用外源添加丙氨酸(Ala)、丝氨酸(Ser)和天冬酰胺(Asn)的方式改善培养基成分,并探究复配氨基酸促进香菇生长的可能代谢途径.[方法]在三因素三水平上,通过响应面...     

两株多环芳烃降解菌协同对菲-镉污染的去除特性北大核心

【目的】从污染土壤中分离筛选一株多环芳烃降解菌,并探究其与Pseudomonas aeruginosa B6-2构建的混菌体系对菲-镉复合污染的修复效能,以及微生物代谢特性对不同镉浓度赋存的响应特性,以期为复合污染的生物修复提供优良菌株资源及应用技术参考。【方法】采用富集驯化、筛选纯化方法得到一株多环芳烃降解菌,通过生理生化特征和16S rRNA基因序列分析进行鉴定。利用高效液相色谱法和电感耦合等离子体质谱法评估不同镉浓度赋存下各反应体系对菲和镉的去除效能;通过菌体细胞形态的扫描电镜观测及菌株代谢活性检测,探讨镉胁迫对菲生物降解过程的影响机制。【结果】筛选得到一株具有重金属耐受性和多环芳烃高效降解菌SZ-3,经鉴定为节杆菌属;降解菌协同体系(M)具有良好的菲降解效能和抗镉胁迫优势。镉胁迫浓度为0.5、10 mg/L时,M对菲和镉的去除率分别高于85%、80%;镉胁迫浓度为25、50 mg/L时,2种污染物的去除率均大于65%。扫描电镜分析表明,镉胁迫导致菌体表面粗糙且出现不同程度变形,菌体间黏附性和聚集性提高。反应周期内,邻苯二酚1,2-双加氧酶活性与电子传递体系活性随镉浓度增加而降低,两者变化与菲降解速率变化一致。【结论】Arthrobacter sp.SZ-3是一株PAHs高效降解菌,能与Pseudomonas aeruginosa B6-2协同高效修复菲-镉复合污染,随着初始镉胁迫浓度增加,混菌协同对目标污染物去除的优势显著。     

Role of Oxalic Acid Overexcretion in Transformations of Toxic Metal Minerals by Beauveria caledonica

The fungus Beauveria caledonica was highly tolerant to toxic metals and solubilized cadmium, copper, lead, and zinc minerals, converting them into oxalates. This fungus was found to overexcrete organic acids with strong metal-chelating properties (oxalic and citric acids), suggesting that a ligand-promoted mechanism was the main mechanism of mineral dissolution. Our data also suggested that oxalic acid was the main mineral-transforming agent. Cadmium, copper, and zinc oxalates were precipitated by the fungus in the local environment and also in association with the mycelium. The presence of toxic metal minerals often led to the formation of mycelial cords, and in the presence of copper-containing minerals, these cords exhibited enhanced excretion of oxalic acid, which resulted in considerable encrustation of the cords by copper oxalate hydrate (moolooite). It was found that B. caledonica hyphae and cords were covered by a thick hydrated mucilaginous sheath which provided a microenvironment for chemical reactions, crystal deposition, and growth. Cryo-scanning electron microscopy revealed that mycogenic metal oxalates overgrew parental fungal hyphae, leaving a labyrinth of fungal tunnels within the newly formed mineral matter. X-ray absorption spectroscopy revealed that oxygen ligands played a major role in metal coordination within the fungal biomass during the accumulation of mobilized toxic metals by B. caledonica mycelium; these ligands were carboxylic groups in copper phosphate-containing medium and phosphate groups in pyromorphite-containing medium.     

锑矿废水影响下水库沉积物中细菌群落结构特征研究

【背景】水库沉积物中的微生物是水生态系统的重要组成部分,在沉积物物质循环中起重要作用。【目的】揭示含锑废水影响下水库表层沉积物中细菌群落结构特征及影响因子。【方法】基于Illumina高通量测序技术,对冷水沟水库表层沉积物细菌群落结构进行研究并分析其与沉积物理化性质的相关性;基于FAPROTAX软件对细菌功能进行预测分析。基于重金属污染负荷指数法评价水库重金属污染情况。【结果】高通量测序结果表明冷水沟水库的细菌群落较为丰富,主要由变形菌门(Proteobacteria,40.32%-20.19%)、拟杆菌门(Bacteroidetes,25.89%-4.44%)、脱硫杆菌(Desulfobacter,9.43%-2.02%)等81个门570个属组成。相关性分析表明,不同提取形态的锑及水溶态锑与多个不同分类水平下的细菌群落有显著的相关性。FAPROTAX软件对细菌功能进行预测,结果表明,化能异养功能细菌占优势(占总细菌的14.59%-23.58%),包括化能异养(Chemoheterotrophy)和需氧化能异养(Aerobic Chemoheterotrophy);此外,与碳、氮、硫元素循环有关的功能微生物以及人类病原致病微生物的相对丰度(占总细菌的12.42%-32.89%)也较高,这与水库的地理条件、周边环境及污染物类型有较大的相关性。重金属污染负荷指数法评价结果表明,水库范围重金属污染较重。【结论】研究区域受锑矿废水影响的水库(2015年建成蓄水)沉积物中细菌的群落以变形菌门(Proteobacteria)及拟杆菌门(Bacteroidetes)为最优势菌群,细菌功能主要以化能异养为主。     

甘蔗鞭黑粉菌侵染甘蔗的早期可视化观察

【目的】甘蔗鞭黑粉菌(Sporisorium scitamineum)引起的甘蔗黑穗病是我国甘蔗生产重要的病害。示踪甘蔗鞭黑粉菌侵染甘蔗的过程将有助于揭示其致病性和甘蔗抗黑穗病机制,为抗病品种的选育以及黑穗病的防治奠定基础。【方法】利用农杆菌介导的遗传转化技术对甘蔗鞭黑粉菌进行黄色荧光标记,对转化子进行配合及致病力检测,将标记菌株接种甘蔗感病品种ROC22及抗病品种中蔗1号、中蔗6号和中蔗9号并进行早期可视化观察。【结果】组成型表达的eYFP不影响标记菌株的配合及致病能力,而且黄色荧光性状能通过冬孢子稳定遗传。激光共聚焦显微观察表明,注射接种病原菌第5天,在感病品种ROC22的生长点已可见荧光菌丝及少量聚集状菌丝体,在抗病品种中蔗1号、中蔗6号和中蔗9号中可见少量单一丝状菌丝,无聚集状菌丝体。接种后35 d,在ROC22中可见大量聚集状菌丝体,但在中蔗品种中的聚集状菌丝体明显较少,而以中蔗1号最少。【结论】成功构建了甘蔗鞭黑粉菌侵染甘蔗的荧光示踪系统,并发现中蔗系列品种存在抑制甘蔗鞭黑粉菌菌丝体在细胞间扩展的机制。     

混料设计优化黑木耳菌丝生长的农业剩余物配方

【背景】菌林矛盾日益突出,农业剩余物资源丰富,可作为食用菌栽培主要基质。【目的】筛选出适合黑木耳菌丝生长的农业剩余物配方。【方法】以大豆秸秆、油菜秸秆、玉米秸秆、花生秸秆、小麦秸秆和杂木屑等6种基质为原料,运用单纯形格子法进行配方设计,分析不同基质交互作用对黑木耳菌丝生长速率、菌丝生长指数、漆酶酶活、多酚氧化酶酶活和纤维素酶酶活的影响。【结果】在这些农业剩余物基质中,大豆秸秆基质最适合黑木耳菌丝生长,其次是油菜秸秆。3种主料共同作用可以优化出最适合黑木耳菌丝生长的基质配比。【结论】最终优化出一个适合黑木耳菌丝生长的农业剩余物配方：杂木屑49.4%、油菜秸秆16.4%、大豆秸秆12.2%、麦麸20%、蔗糖1%、CaSO₄ 1%。本研究为“以草代木”栽培黑木耳提供了理论基础。     

耐镉促生缺陷短波单胞菌Y01Z的分离与表征

【目的】本研究旨在从湖北地区镉污染严重的水稻根际土壤中,分离并鉴定能耐受高浓度的镉离子,同时具有镉去除能力和促进植物生长的细菌。【方法】采用稀释涂布平板和镉浓度梯度驯化的方法,成功分离出一株最高可耐受700 mg/L CdCl2且稳定生长的菌株,命名为Y01Z,并结合形态学、生理生化和分子生物学等方法对其进行鉴定。【结果】结果显示该菌株属于缺陷短波单胞菌(Brevundimonas diminuta),其最适生长条件为pH值7.0、温度30°C、NaCl浓度0.5%。扫描电镜和透射电镜分析显示,Y01Z通过拉长细胞尺寸以确保在高浓度镉处理下的生存和繁殖,同时能吸附镉离子,并将其输送到细胞内沉积。傅里叶变换红外光谱分析显示,Cd2+与细菌表面羧基、羟基、羰基和酰胺等官能团结合。经过104 h的培养,Y01Z菌株能够去除高达75%的总添加镉,从300 mg/L降至74.73 mg/L。此外,该菌株还具有促进植物生长的功能,如溶解磷,产生铵态氮和吲哚乙酸,并含有嗜铁载体等物质。【结论】本研究探讨了缺陷短波单胞菌Y01Z在耐镉、植物促生方面的性质,以及在修复镉污染土壤方面的应用前景。本研究为深...     

莱茵衣藻E2泛素结合酶CrUBC23调控油脂积累

【目的】为研究莱茵衣藻(Chlamydomonas reinhardtii)泛素结合酶(ubiquitin-conjugating enzymes,E2)CrUBC23在莱茵衣藻油脂代谢中的作用,为高产油微藻基因工程改良和揭示藻类油脂合成及代谢调控机理奠定基础。【方法】qRT-PCR分析莱茵衣藻在低氮、低磷胁迫下泛素结合酶CrUBC23表达情况;克隆CrUBC23同源基因干涉片段和全长基因,构建RNAi干涉载体和过量表达载体,转化莱茵衣藻并检测生物量和油脂含量;构建CrUBC23-GFP融合表达载体,用农杆菌浸染洋葱表皮细胞进行亚细胞定位。【结果】莱茵衣藻在低氮、低磷胁迫下CrUBC23基因表达量显著增加,增加幅度分别为正常培养的4.98–5.80倍和1.85–5.20倍。RNAi干扰结果显示,转基因藻细胞中性脂含量降低5.5%,总脂含量降低3.16%–17.6%。过量表达结果显示,转基因藻细胞中性脂含量增加8.8%,总脂含量增加4.51%–14.03%。【结论】CrUBC23正向调控莱茵衣藻油脂代谢,该基因定位于细胞核。