Institutional Repository of Chengdu Institute of Biology, CAS
Not a member yet
6513 research outputs found
Sort by
Screening and degradation characteristics of a tetracycline-degrading bacterial strain
No full text四环素类抗生素在畜禽养殖业中的大量使用给生态环境带来了严重危害.从活性污泥中筛选到一株对四环素具有良好降解能力的高效降解菌株,命名为TTC-1.形态观察、革兰氏染色及16S rRNA序列分析表明该菌株为革兰氏阴性菌,并鉴定为克雷伯氏菌(Klebsiella pneumoniae).采用单因素试验分别研究温度、初始pH、接种量、金属盐种类等因素对该菌株四环素降解效率的影响.基于单因素试验结果,通过响应面优化该菌的四环素降解条件,拟合得到二次多项回归模型,确定了降解四环素的最佳条件为温度34.4 ℃,pH 7.22,MnSO_4浓度0.32 g/L.在最优条件下,预测四环素降解率为93.77%,验证值为94.26%,说明建立的模型具有较高的精度.本研究表明TTC-1对四环素具有良好降解效果,有望为该菌在含四环素的实际废水生物强化处理过程中提供理论参考
Effects of Simulated Nitrogen Deposition on Soil Organic Carbon Fractions and Soil Physico-chemical Properties in Picea asperata Plantation in Sichuan
No full text大气氮沉降已成为目前全球性的环境问题之一。氮沉降可能影响森林生态系统碳循环的过程,研究氮沉降对森林土壤有机碳库的影响,有利于正确评估森林生态系统碳循环过程及其对全球气候变化的响应。为探究氮沉降对森林生态系统碳循环的影响,以四川云杉Picea asperata人工林为研究对象,研究了氮沉降(N0,N 0 kg·hm~(-2)·a~(-1);N1,N 60 kg·hm~(-2)·a~(-1);N_2, N 120 kg·hm~(-2)·a~(-1);N3,N 240 kg·hm~(-2)·a~(-1))对云杉人工林土壤有机碳组分的影响。结果表明,模拟氮沉降处理下,土壤总孔隙度(TPO)与土壤容重(BD)变化趋势相反;土壤pH值变化范围在6.58~7.02之间,随N浓度的增加而降低。土壤养分(有机碳SOC、全氮TN、全钾TK、有效磷AP和有效钾AK)和有效养分均呈现出一致性规律,随着N浓度的增加而增加,模拟氮沉降处理下土壤全磷含量差异均不显著(P>0.05)。与对照相比(N0),土壤易氧化有机碳(EOC)、颗粒有机碳(POC)、轻组有机碳(LFOC)、水溶性有机碳(WSOC)和微生物量碳(SMBC)明显受氮沉降的影响。EOC、POC、轻组有机碳(LFOC)和WSOC均呈现出一致性规律,随N处理水平的增加而增加。EOC/SOC比例和微生物熵(MBC/SOC)均随N浓度的增加而增加。通径分析结果表明:1~0.05 mm粒径和TPO对土壤有机碳组分产生直接效应;pH>TPO=(BD>0.05~0.002 mm;土壤养分对土壤有机碳组分产生直接和间接负作用,其中SOC、TN和AK对土壤有机碳组分产生直接效应;TK和AP对土壤有机碳组分产生间接效应;总效应值大小依次为SOC>TN>AK>TK>TP>AP。综合分析表明,氮沉降有利于云杉人工林土壤有机碳组分稳定性的提高,利于土壤有机碳的累积
Spatio-temporal dynamics of two alpine treeline ecotones and ecological characteristics of their dominate species at the eastern margin of Qinghai-Xizang Plateau
No full text热量匮乏是高山树线的主要成因,在全球变暖趋势下对高山树线及其建群种的生态学过程及特征的研究具有重要意义。该文以青藏高原东缘的折多山和剪子弯山两处高山树线(海拔分别为4 265 m和4 425 m)作为研究对象,通过设置垂直样带,同时结合区域温度、降水的长时间序列分析,探究两处树线的时空动态过程,并明确了建群种冷杉(Abies spp.)的生态学特征。结果表明: 1)折多山和剪子弯山区域的气温在过去58年均存在显著的上升趋势(分别上升了0.72和0.91 ℃),而折多山和剪子弯山区域降水均存在微弱的降低趋势。2)折多山的峨眉冷杉(A. fabri)龄级结构呈反J形,剪子弯山的鳞皮冷杉(A. squamata)龄级结构呈双峰形,二者种群结构均相对稳定。3)在小尺度上,种子扩散限制使得两处树线的冷杉聚集分布。在大尺度上,折多山峨眉冷杉亦呈聚集分布,而剪子弯山鳞皮冷杉受生长环境以及种内或种间关系的影响呈随机分布。4)两处样地建群树种的树高和基径均随海拔升高而降低,位于树线交错带上部的冷杉均呈现树高生长大于径向生长的异速生长关系,而位于样地中、下部位的冷杉大部分呈等速生长关系。5)相比10年前,折多山和剪子弯山的树线及树种线位置均无明显变化,剪子弯山鳞皮冷杉种群的树木密度亦无明显变化,而折多山的树木个体数提高了约25%;相比20年前,折多山和剪子弯山的树种线分别上移了50和30 m,树线位置分别升高了75和40 m,树木个体数亦明显增加,分别提高了约220%和100%。树线及其建群种在较大时空尺度上主要受热量的控制,而在较小时空尺度上受温度及生长环境共同作用的影响
Discriminating five Polygonatum medical materials and monitoring their chemical changes associated with traditional process by FT-IR spectroscopy coupled with multivariate analysis
No full textSeveral Polygonatwn species are important medicinal materials as tonic to cure disorders in China. Because of their different medical effects, it is desired to distinguish them at species level. In addition, to ensure and control their medical quality, it is also important to monitor their chemical changes associated with traditional process. Taking the advantages of Fourier transform infrared spectroscopy (FT-IR) and multivariate analysis, we developed a convenient, fast and reliable approach to discriminate and quality control these materials. Despite similar absorption patterns, each species also presented spectral differences, especially on the FT-IR fingerprint range of 1800-600 cm(-1). Second derivative method obviously enlarged those differences and then showed more species specific features. These spectral differences could be used as powerful discriminating points to distinguish them. PCA results showed that each species separated clearly with their biological replicates grouped together, which indicated that the variance between species is greater than within species, therefore, these species could be distinguishable. Using this approach, the five herbal materials were discriminated successfully in their raw, processed and ethanol extracted formats. On the other hand, visual inspecting infrared spectra of samples from 1 to 9 process steps, absorbance near 1737, 1259, 817 and 780 cm(-1) increased gradually but decreased gradually at 927 cm(-1). Besides, spectral contour near 1050 cm(-1) changed sharply with process treatment. These spectral changes indicated that hydrolyzing polysaccharides into oligo-and mono-saccharides, especially glucose and fructose, are the main chemical changes associated with traditional process. This is consistent with the traditional experience that the processed materials are dark as night and sweet as malt sugar. Meanwhile, our results also indicated that their chemical constituents changed profoundly after process, which might be the chemical basis for raw and processed materials have different medical effects. Based on absorbance at 817 and 780 cm(-1) and the color, taste, smell of processed materials followed by energy efficacy, raw materials had to be processed more than 21 h to ensure their quality. This research shows the potential of FT-IR spectroscopy coupled with multivariate analysis to discriminate different herbs and to monitor chemical changes with process and then control their quality. This could be very helpful to ensure the quality, safety, and efficacy of herbs on clinical practices
Difference in soil pH values between Picea asperata and Abies faxoniana stands in subalpine regions and a preliminary study on its mechanism
No full text比较了川西亚高山针叶林主要树种粗枝云杉(Picea asperata)和岷江冷杉(Abies faxoniana)样地各土层(05 cm、510 cm、1020 cm)土壤pH值差异,并从两树种养分吸收和养分归还相关累积H~+输入方面探究其差异原因。研究结果表明:云杉样地各土层土壤pH值均显著高于冷杉样地(P<0.05);云杉样地地被物累积H~+输入显著低于冷杉样地(P<0.05);云杉样地凋落物中P、Mg、N、C平均浓度显著低于冷杉(P<0.05),而Ca、C/N、木质素/N、C/P显著高于冷杉样地(P<0.05),两树种凋落物中木质素、K平均浓度无显著差异。云杉和冷杉凋落物化学特性主成分分析PC_1、PC_2方差贡献率分别为73.7%和15.6%,累积方差贡献率为89.4%,其中PC_1主要综合Ca、C/P、C/N、木质素/N、P、N、Mg的信息;PC_2主要综合木质素、K、C的信息。各土层土壤pH值均与地被物累积H~+输入显著负相关,与PC_1样本分数显著正相关。研究结论:云杉和冷杉样地土壤pH值存在显著树种差异,且云杉使土壤pH值变大,冷杉使土壤pH值变小,这主要与地被物形成以及凋落物化学特性有关,即与凋落物的量和凋落物分解速率、凋落物养分归还率密切相关
Differential responses of Picea asperata and Betula albosinensis to nitrogen supply imposed by water availability
No full textA pot experiment was conducted to investigate the effects of nitrogen (N) addition (0, 20, 40 g N m(-2) year(-1), N0, N20, N40, respectively) on the growth, and biomass accumulation and allocation of coniferous and deciduous (Picea asperata Mast. and Betula albosinensis Burk.) seedlings under a range of soil moisture limitation (40%, 50%, 60%, 80% and 100% of field capacity, FC). At 100% FC, growth of shade-tolerant P. asperata increased with N supply, while that of shade-intolerant B. albosinensis reached a maximum at N20, declining somewhat thereafter. At 60% FC and lower moisture content, water availability limited the growth of P. asperata seedlings, while N availability became progressively limiting to growth with moisture increasing above 60% FC. The transition from principally water-limited response to N-limited response in B. albosinensis occurred at lower moisture content. For P. asperata, these patterns reflected the responses of roots, consistent with changes in root/shoot biomass. For B. albosinensis the response reflected changes in shoot dimensions and root biomass fraction, the latter decreasing with size and foliar [N]. We are not aware of another study demonstrating such differences in the shape of the growth responses of seedlings of differing potential growth rate, across a range in belowground resource supply. The responses of leaf photosynthesis (as well as photosynthetic water and N-use efficiencies) were consistent with the observed growth response of P. asperata to water and N availability, but not of B. albosinensis, suggesting that leaf area dynamics (not measured) dominated the response of this species. Betula albosinensis, a fast-growing species, has a relative narrow range of soil water and N availability for maximum growth, achieved by preferential allocation to the shoot as resources meet the requirements at moderate N and water supply. In contrast, P. asperata increases shoot biomass progressively with increasing resources up to moderate water supply, preferentially growing more roots when resources are not limiting, suggesting that its capacity to produce shoot biomass may reach a biological limit at moderate levels of resource supply
Changes in plant nitrogen acquisition strategies during the restoration of spruce plantations on the eastern Tibetan Plateau,China
No full textDespite the importance of plant nitrogen (N) acquisition strategies for plant growth and the structure and functioning of ecosystems, few studies have investigated the N acquisition preference of plants and their reliance on various N sources (nitrate (NO3-), ammonium (NH4+), and organic N (DON) in soil) during different stages of plantation restoration caused by land-use change. In this study, we used the isotopic mass-balance methods to quantitatively estimate the contributions of N sources (NO3- vs. NH4+ vs. DON) and plant N preferences in spruce (Pleat asperata Mast.) plantations of different ages (i.e., 20, 30, 40, 50, and 70 years old) on the eastern Tibetan Plateau, China. Across all restoration stages, while plants in spruce plantations preferred soil inorganic N over soil DON, soil DON was a notable N contributor to plant N nutrition, with 23%-44% of plant N derived from DON. Moreover, with the development of plantation restoration, the N source preferences of plants switched from NO3- (i.e., 20- and 30-yr-old plantations) to NH4+ (age of plantations >= 40 years old). Our results suggest that soil DON can be an important N source in alpine coniferous forests. In addition, the shift in the dominant N source during plantation restoration may manifest a strategic adjustment of plant N acquisition in response to changes in soil N availability and/or physiological traits
Influence of phosphorus application and water deficit on the soil microbiota of N2-fixing and non-N-fixing tree
No full textSoil water content and phosphorus availability are important factors that are expected to shape soil microbiota. Although the impacts of water deficit (drought) on soil microbiota have been reasonably studied, microbial responses to P addition combined with soil water deficit have rarely been reported, especially in relation to the identity of aboveground tree species. This study was conducted to evaluate the main and interactive effects of drought and P addition on the soil protozoa, microbial communities as determined by phospholipids fatty acids (PLFAs) and enzyme activities in a soil vegetated with N-2-fixing or non-N-fixing tree species and in a non-vegetated soil. The results indicated that the effects of drought, P addition, and their interaction on soil microbiota and chemical properties varied depending on the type of aboveground tree species. Drought significantly decreased the abundance of ciliates, amoebae, total protozoa, and most of the microbial community compared to the optimum water treatment, but the effect was more pronounced under non-N-fixers compared to N-2-fixers. P addition significantly increased the nitrate nitrogen (NO3--N) and dissolve organic nitrogen (DON) in drought treated soil as compared to the well-watered counterpart, irrespective of the planting systems. The interaction of P with drought significantly increased the mean abundance of ciliates, flagellates, amoebae, and the total protozoa in soil vegetated with non-N-fixers and actinomycetes PLFAs, G(+) bacterial PLFAs, and total bacterial PLFAs in the soil vegetated with N-2-fixers. Our finding points to an essential role of P addition and N-2-fixing trees on soil microbiota under drought stress. This study suggests that the effects of P application depend on its interaction with drought and that drought had decreasing effects on the abundance of ciliates, flagellates, amoebae, total protozoa, and the soil microbial communities, but the extent of it effects varied with tree species
Effect of dry-rewetting stress on response pattern of soil prokaryotic communities in alpine meadow soil
No full textSoil microorganisms are recognized as key players in all biogeochemical cycles. However, little effort has been paid to incorporate them in predictive models for future climate change. Here, we investigated the variation of prokaryotic community composition in alpine meadow soil from the Qinghai-Tibet Plateau under dry-rewetting stress using MiSeq sequencing approach. We incubated soils treated by various frequencies of rewetting and durations of desiccation. Emission rates of methane, carbon dioxide and nitrous oxide were measured every week during five months of incubation, and soil samples were taken each month for community composition analysis. Our results revealed that soil prokaryotic community showed different response patterns to dry-wetting cycles. Diversity indices significantly increased in soils under short-term drought and soils rewetted after long-term drought. Higher niche partitioning was promoted by higher frequencies of disturbance and rapid physiological activation of inactive microbial communities during desiccation, allowing colonization by a diverse array of organisms. Null model percentage of NTI revealed a strong phylogenetic relatedness of soil prokaryotic communities across all treatments and incubation times, suggesting that desiccation and rewetting events were strong biological filters shaping community assemblies. Our results also indicated different responses of various genera belonging to same phylum. These results suggest that prokaryotes that are well adapted to extremely stressful conditions such as long-term desiccation may release more greenhouse gasses in a positive feedback loop and that this prospect should be considered when modeling climate change
The specialisation of the third metacarpal and hand in arboreal frogs: Adaptation for arboreal habitat?
No full textSkeletal morphology is directly associated with habitat characteristics. To investigate the arboreal adaptation, we studied the osteological morphology of the forelimbs and the third metacarpals of arboreal frogs (Rhacophoridae and Hylidae) and non-arboreal frogs (Bombinatoridae, Bufonidae, Megophryidae, Ranidae, and Microhylidae) using transparent specimens or X-rays of skeletons. Our results revealed that the bony knob on the third metacarpal, which formed by a dilated and elongated lateral articular cartilage (AL) through endochondral ossification, occurred only in species of Rhacophorinae. The results of the phylogenetic comparative methods and correlation analysis strongly supported the conclusion that the bony knob is a phylogenetic independent evolution trait and had a significant correlation with the arboreal habitat. Furthermore, anatomical observation showed that a muscle adhered to the bony knob. Therefore, we speculated that the bony knob might act as an enlarged attachment point for larger or more musculatures to help with grasping. In addition, the relative length of the hand showed a significant difference between arboreal and non-arboreal species (p=.007), suggesting that longer hands might be an arboreal adaptive trait. Overall, this study leads to a deeper understanding of the arboreal adaptation