产低温淀粉酶的海洋真菌筛选及研究

从黄、东海的近海海底泥样中分离到6株产淀粉酶活力较高的丝状真菌，对其中产淀粉酶活力最高的Penicillum sp.FS 010441号菌体产酶条件及酶学性质进行了初步研究。该菌最适生长温度为15℃，最高生长温度为40℃，在0℃也可生长，是典型的耐冷菌。对Penicillum sp.FS 010441进行固体培养每克干曲酶活达2622U.Penicillum sp.FS 010441所产低温淀粉酶最适作用pH值为6.0，最适反应温度为40℃，但在0℃也表现出一定酶活，而在15℃有较强的酶活。该低温淀粉酶在洗涤、食品、饲料、制药和酿酒等行业可望有广泛的应用前景。     

一株抗植物致病真菌的深海霉菌的鉴定和活性成分理化性质分析

从印度洋深海底泥中分离到一株真菌S2915,经ITS基因序列分析及显微形态观察,鉴定S2915为支顶孢属Acremonium sp.真菌.其发酵液对5株植物致病真菌有明显的抑制作用.经硫酸铵沉淀后的抗菌活性分析,可以初步判断该抗菌活性成分为蛋白类物质,且最佳硫酸铵饱和浓度为70％(m/m).初步分析了该抗菌粗蛋白的理化性质,结果表明,该活性物质具有很好的耐热性,经60、80、100℃甚至121℃处理后,活性均无明显差异;耐强酸强碱,在pH值为2～12范围内活性不受影响;紫外照射0～12h及用蛋白酶K、胰蛋白酶、木瓜蛋白酶处理后,活性均没有减弱;但对多种有机溶剂比较敏感,经三氯甲烷、乙酸乙酯、乙醚和丙酮处理后,抗菌活性受到不同程度的抑制,其抑制率分别为35％、25.7％、22.9％、12.9％.证明该抗菌活性物质高效、稳定,可用于抗真菌农药的开发应用.     

南海3种可食绿藻化学成分及其营养评价

对南海3种可食绿藻条浒苔(Enterom orpha clathrata)、石莼(Ulva lactucaL.)和总状蕨藻(Caulerpa racem o-sa)的主要化学成分进行了分析,结果显示:多糖、蛋白质和粗纤维是构成藻体的主要化学成分,占藻体的92%以上,其中膳食纤维占64.22%~70.80%;蛋白质占14.15%~18.91%,平均为16.16%,且蛋白质中必需氨基酸含量高,占总氨基酸的42.37%~48.37%,氨基酸评分在73分以上,第一限制氨基酸随藻种而变化;脂肪含量在0.51%~0.81%之间,均低于1%,多不饱和脂肪酸和必需脂肪酸含量高,其含量分别为其总量的56.10%~63.20%和37.71%~39.39%;矿物质和维生素含量丰富,尤其是Fe、Zn、I等矿质元素和维生素C含量高。3种可食绿藻是高膳食纤维,高蛋白,低脂肪,低热能,且富含矿物质和维生素的天然理想保健食品原料。     

塔里木河下游丛枝菌根植物的侵染

通过对塔里木河下游自然和人工植物群落中的15种主要建群种植物根系菌根的定殖状况的调查及对菌根侵染部位、菌根中的泡囊、丛枝和菌丝的观察,其结果显示:其中11种植物可被AM真菌侵染,占所调查植物种总数的73.33%,野生乡土植物表现出较高的菌根侵染率和侵染强度,其中有84.62%的植物为菌根植物,且乔木、多年生草本和灌木类植物全部为菌根植物,一年生草本植物未见AM真菌侵染;人工引入种蓼科的泡果沙拐枣(Calligonum junceum)和藜科的梭梭柴(Haloxylon ammodendron)均未见有AM真菌侵染。丛枝菌根真菌侵染率、侵染强度与植物所属的科属关系较密切,也与真菌群落所处时空环境及土壤深度有关。     

踩踏干扰下生物结皮土壤可培养微生物数量

生物结皮显著影响土壤微生物数量和群落组成。干扰是自然界常见现象,可引起生物结皮盖度及组分发生改变,进而导致生物结皮土壤微生物群落结构的变化。以发育8年的生物结皮为研究对象,采用平板培养法,研究了干扰下生物结皮层和其下0~2 cm土壤微生物数量的动态变化。结果表明：（1）干扰第2天不同菌种均有响应。生物结皮层土壤细菌、真菌和放线菌数量波动范围分别为91.2×10⁵~303.5×10⁵ cfu·g^-1,0~487.2×10³ cfu·g^-1和23.0×10⁵~376.1×10⁵ cfu·g^-1;下层0~2 cm波动范围分别为65.6×10⁵~792.3×10⁵ cfu·g^-1,8.0×10³~506.3×10³ cfu·g^-1和17.3×10⁵~801.3×10⁵ cfu·g^-1。（2）生物结皮层和下层0~2 cm土壤细菌数量分别在干扰后第10天和第7天恢复稳定,真菌数量在第16天和第8天趋于平稳,放线菌数量在第8天和第4天恢复稳定。生物结皮层较0~2 cm土壤微生物数量恢复稳定滞后。（3）重新稳定后生物结皮层和下层0~2 cm细菌数量较干扰前分别下降了81.8%和79.6%.生物结皮层真菌数量显著增加,是干扰前的7.43倍;下层0~2 cm真菌数量下降了70.1%。生物结皮层和下层0~2 cm放线菌数量较干扰前分别降低46.5%和72.6%。（4）干扰显著改变土壤微生物群落结构,受影响程度细菌 > 放线菌 > 真菌变为放线菌 > 细菌 > 真菌。干扰可显著影响土壤微生物数量,但是随着时间延长微生物数量又会达到一个新的稳态,在研究微生物对干扰响应时,采样时间是研究结果的一个重要影响因素。     

An investigation on tolerance and accumulation of a facultative marine fungus <Emphasis Type="Italic">Aspergillus flavus</Emphasis> to pentavalent arsenic

Tolerance of a facultative marine fungus Aspergillus flavus towards As (V) was tested. Luxuriant growth of the test isolate was observed in culture media with As (V) concentrations of 25 mg L⁻¹ and 50 mg L⁻¹, indicating its tolerance to the metal. Accumulation rate of arsenic was always higher when exposed to As (V) at 50 mg L⁻¹ than at 25 mg L⁻¹. The study reveals Aspergillus flavus as a promising candidate for environmental bioremediation. Arsenic contents (mg g⁻¹) in the fungus when exposed to 50 mg L⁻¹ As (V) were measured as 11.1773, 4.0983, and 8.0000 mg g⁻¹ on day 3, 6 and 9, respectively. The highest content was observed initially, i.e. on day 3, followed by a decline and a rise again. These results provide baseline information for further explorations regarding the exploitation of the fungus for arsenic removal.     

自制Z-Ⅱ碘探针应用于快速测定食盐及海带中的无机碘和有机碘

目前食盐和海带产品中碘含量分析主要是总碘含量测定,而无机碘与有机碘形态分析主要依靠大型精密仪器联用技术。本文研制了一种基于硫化碘化银法研制的全固态、无内参液的晶体膜电极(Z-Ⅱ碘探针),采用聚四氟乙烯消化罐微波消解技术,建立了食用盐及海带中的无机碘及有机碘含量测定方法。实验结果表明:食盐中无机碘含量为20mg/kg,有机碘含量为2mg/kg,海带中有机碘含量为2.9×10~3mg/kg。无机碘及有机碘含量分别在10～100mg/kg范围内线性关系良好,加标回收率为97.1%～101.0%,检出限均为1mg/kg。本方法应用于食盐和海带实际样品中的碘含量测定,无机碘和有机碘测定结果的相对标准偏差(RSD)分别小于0.92%和2.49%,且测定结果与国家标准方法和紫外分光光度法的测定结果基本一致。该方法具有试剂耗量少、成本低的特点,操作方便,可应用于有机碘和无机碘含量的测定。     

Freshwater lichens and habitat zonation of mountain streams

Freshwater lichens of selected Carpathian streams were investigated to identify their diversity and distribution patterns. Lichens were investigated along six transects, each running across three different habitats (hydrological zones: submerged, splash and riparian), established in upper, middle and lower reaches of the streams and the data were a subject to statistical analyses. The studied mountain streams provided suitable habitats for a number of aquatic and semi-aquatic lichens and species richness in both streams was very similar. Overall, 52 species of lichens were identified from all sampling plots (γ diversity). Species number for a single plot (α diversity) ranged from 1 to 14 species and differences in species composition between the plots (β diversity) were high. Differences were mainly noted for typical terrestrial lichens occurring in riparian zones. The location along the stream reaches did not have a significant effect on species diversity and distribution. The hydrological zone appeared to be the most important predictor explaining the small-scale occurrence and diversity of lichens with species assembled into distinct, low-diversity communities in the transition from submerged to riparian habitats. The distinction among hydrological zones and their lichen biota were corroborated by nMDS analyses. The method of defined plots provides a way of recording baseline data for a particular river, which can be repeated (monitor) in the future.     

Arbuscular mycorrhizal fungi improve reestablishment of Leymus chinensis in bare saline-alkaline soil: Implication on vegetation restoration of extremely degraded land

Salinization and alkalinization are increasing problems in the world. Some land has been degraded to bare saline-alkaline soil where vegetation restoration is difficult because high toxic ionic content and pH are harmful to the survival of introduced plants. We grew Leymus chinensis with and without arbuscular mycorrhizal fungi (Glomus mosseae and G. geosporum) in either pots filled with soil from bare saline-alkaline land, or transplanted seedlings into field plots, to determine the influence of AM fungi on the reestablishment of this dominant grass species in bare degraded land. Association with AM fungi increased the absorption of N, P, K⁺, Ca²⁺, but decreased Mg²⁺, Na⁺ and Cl⁻ uptake under saline-alkaline stress. Therefore, higher K/Na, Ca/Na, P/Na, and P/Cl ratios were found in the inoculated plants. Plants inoculated with AM fungi accumulated significantly higher biomass, root/shoot ratio and tiller number than non-inoculated plants. AM fungi also significantly increased the survival of seedlings when they were transplanted into a bare saline-alkaline land in the field. The improvement of survival, growth and asexual reproduction of inoculated plants indicated that the plant-AM fungi mutualism could improve the reestablishment of vegetation in bare saline-alkaline soil, drive the vegetation restoration to a community dominated by original species.     

Marine-derived filamentous fungi and their potential application for polycyclic aromatic hydrocarbon bioremediation

Eight marine-derived fungi that were previously selected for their abilities to decolorize RBBR dye were subjected to pyrene and benzo[a]pyrene degradation. The fungus Aspergillus sclerotiorum CBMAI 849 showed the best performance with regard to pyrene (99.7%) and benzo[a]pyrene (76.6%) depletion after 8 and 16 days, respectively. Substantial amounts of benzo[a]pyrene (>50.0%) depletion were also achieved by Mucor racemosus CBMAI 847. Therefore, these two fungal strains were subjected to metabolism evaluation using the HPLC-DAD-MS technique. The results showed that A. sclerotiorum CBMAI 849 and M. racemosus CBMAI 847 were able to metabolize pyrene to the corresponding pyrenylsulfate and were able to metabolize benzo[a]pyrene to benzo[a]pyrenylsulfate, suggesting that the mechanism of hydroxylation is mediated by a cytochrome P-450 monooxygenase, followed by conjugation with sulfate ions. Because these fungi were adapted to the marine environment, the strains that were used in the present study are considered to be attractive targets for the bioremediation of saline environments, such as ocean and marine sediments that are contaminated by PAHs.