中国航空碳排放及其效率时空演化特征分析

航空碳排放不仅影响空气质量且可造成温室效应。中国正处于从民航大国向民航强国迈进的关键时期，提高航空碳排放效率是行之有效的航空碳减排手段。运用可拓展随机性环境影响评估模型(STIRPAT)对中国2004—2019年航空碳排放总量的时空演变特征进行分析，以探明不同尺度区域航空碳排放的空间差异与空间关联表现；运用基于非期望产出的超效率松弛变量模型(SBM)和标准差椭圆分析法(SDE)对中国航空碳排放效率的时空分布与格局演化过程进行判定，以分析各省域航空碳排放效率的差异，并给出有效的航空碳减排方略。研究发现：2004—2019年，中国航空碳排放总量持续增长，航空碳排放增长率和航空碳排放强度均呈波动下降趋势；四大经济区航空碳排放总量分布总体表现为“东部>西部>中部>东北”的格局，东部仍是中国航空碳排放的主要区域；高碳排放区较分散，还未形成省域之间连片的碳排放高值区。2004—2019年，中国航空碳排放效率总体呈现“M”型波动上升趋势，各省域航空碳排放效率均不同程度的提高，但主要以低效率区、中效率区为主；各省域之间的航空碳排放效率差异性经历了逐渐减小到逐步增大的过程，但总体航空碳...     

Forest floor photosynthesis and respiration in a drained peatland forest in southern Finland

Background: Although forest floor forms a large biomass pool in forested peatlands, little is known about its role in ecosystem carbon (C) dynamics.

Aim: We aimed to quantify forest floor photosynthesis (P _FF) and respiration (R _FF) as a part of overall C dynamics in a drained peatland forest in southern Finland.

Methods: We measured net forest floor CO₂ exchange with closed chambers and reconstructed seasonal CO₂ exchange in the prevailing plant communities.

Results: The vegetation was a mosaic of plant communities that differed in CO₂ exchange dynamics. The reconstructed growing season P _FF was highest in the Sphagnum community and lowest in the feather moss communities. On the contrary, R _FF was highest in the feather moss communities and lowest in the Sphagnum community. CO₂ assimilated by the forest floor was 20–30% of the total CO₂ assimilated by the forest. The forest floor was a net CO₂ source to the atmosphere, because respiration from ground vegetation, tree roots and decomposition of soil organic matter exceeded the photosynthesis of ground vegetation.

Conclusions: Tree stand dominates C fluxes in drained peatland forests. However, forest floor vegetation can have a noticeable role in the C cycle of peatlands drained for forestry. Similarly to natural mires, Sphagnum moss-dominated communities were the most efficient assimilators of C.     

祁连山南麓高寒湿地生态系统呼吸季节、年际动态及影响因素

由于青藏高原高海拔、低温的特殊环境，使得生态系统呼吸(RE)对气候变化的响应极其敏感，然而对高寒湿地生态系统长时间尺度上的RE动态特征及驱动机制的研究相对薄弱。以青藏高原东北部高寒湿地为研究对象，分析了基于涡度相关系统观测的高寒湿地2004—2016年的CO₂通量排放动态及影响机制，对预测高寒湿地碳平衡对未来气候变化的响应具有重要意义。结果表明：高寒湿地在2004—2016年的月平均RE表现为单峰变化趋势，在8月达到峰值；年RE表现为逐年升高的趋势(P<0.05),年RE均值为(608.9±65.6) g C m^-2 a^-1;生长季RE约是非生长季RE的2.7倍，线性回归分析表明生长季RE(r~2=0.66,P=0.001)、非生长季RE(r~2=0.47,P=0.01)与全年RE呈极显著正相关。在月尺度上，分类回归树分析和线性回归分析表明土壤温度是月RE的最主要控制因素，暗示高寒湿地的土壤呼吸对整个生态系统的碳排放至关重要。在年际尺度上，生长季积温与生长季RE呈显著正相关(P<0.05),而生长季降水(PP...     

Quantitative Metaproteomics and Activity-based Protein Profiling of Patient Fecal Microbiome Identifies Host and Microbial Serine-type Endopeptidase Activity Associated With Ulcerative Colitis

The gut microbiota plays an important yet incompletely understood role in the induction and propagation of ulcerative colitis (UC). Organism-level efforts to identify UC-associated microbes have revealed the importance of community structure, but less is known about the molecular effectors of disease. We performed 16S rRNA gene sequencing in parallel with label-free data-dependent LC-MS/MS proteomics to characterize the stool microbiomes of healthy (n = 8) and UC (n = 10) patients. Comparisons of taxonomic composition between techniques revealed major differences in community structure partially attributable to the additional detection of host, fungal, viral, and food peptides by metaproteomics. Differential expression analysis of metaproteomic data identified 176 significantly enriched protein groups between healthy and UC patients. Gene ontology analysis revealed several enriched functions with serine-type endopeptidase activity overrepresented in UC patients. Using a biotinylated fluorophosphonate probe and streptavidin-based enrichment, we show that serine endopeptidases are active in patient fecal samples and that additional putative serine hydrolases are detectable by this approach compared with unenriched profiling. Finally, as metaproteomic databases expand, they are expected to asymptotically approach completeness. Using ComPIL and de novo peptide sequencing, we estimate the size of the probable peptide space unidentified (“dark peptidome”) by our large database approach to establish a rough benchmark for database sufficiency. Despite high variability inherent in patient samples, our analysis yielded a catalog of differentially enriched proteins between healthy and UC fecal proteomes. This catalog provides a clinically relevant jumping-off point for further molecular-level studies aimed at identifying the microbial underpinnings of UC.     

Aeromonas hydrophila strains as biocatalysts for transglycosylation

Abstract

Microbial transglycosylation is useful as a green alternative in the preparation of purine nucleosides and analogues, especially for those that display pharmacological activities. In a search for new transglycosylation biocatalysts, two Aeromonas hydrophila strains were selected. The substrate specificity of both micro-organisms was studied and, as a result, several nucleoside analogues have been prepared. Among them, ribavirin, a broad spectrum antiviral, and the well-known anti HIV didanosine, were prepared, in 77 and 62% yield using A. hydrophila CECT 4226 and A. hydrophila CECT 4221, respectively. In order to scale-up the processes, the reaction conditions, product purification and biocatalyst preparation were analyzed and optimized.     

Cytoplasmic Acidification May Occur in High-Pressure Carbon Dioxide-Treated Escherichia coli K12

While studying the mechanism by which high-pressure carbon dioxide treatment (HCT) inactivates bacteria, we found that the efficiency of DNA recovery via phenol extraction was extraordinarily low from E. coli K12 cells that had been subjected to HCT. DAPI staining of the treated cells, however, revealed that nuclear DNA was present. Most DNA from the cells subjected to HCT was probably caught in the denatured protein layer during phenol extraction. The efficiency of DNA recovery from proteinase-treated crude extracts from cells subjected to HCT was high. Crude extracts of E. coli K12 cells that had not undergone HCT were intentionally acidified with acetic acid to pH 5.2 to cause acidic coagulation of cytoplasmic proteins. The efficiency of DNA recovery from the acidified extracts was low. These results suggest that in cells subjected to HCT, cytoplasmic pH is reduced to around pH 5.2, and that nuclear DNA becomes entangled in coagulated cytoplasmic proteins. Acidification of the cytoplasm might be the primary mechanism by which HCT inactivates bacteria.     

The production of antimicrobial compounds by British marine algae I. Antibiotic-producing marine algae

Using five species of bacteria as the test organisms, 151 species of British marine algae have been screened for the production of antibiotics. Of these, Asparagopsis armata, Bonnemaisonia asparagoides, Bonnemaisonia hamifera, Chondrus crispus, Dilsea carnosa, Gloiosiphonia capillaris, Sphondylothamnion multifidum, Desmarestia aculeata, Desmarestia ligulata, Laminaria digitata, Dictyopteris membranacea, Dictyota dichotoma, Halidrys siliquosa and most members of the family Rhodomelaceae appear to possess outstanding antibacterial properties. Although the production of antibiotics would appear to be a characteristic of several families, it has not been possible to establish any major correlation between taxonomy and antibiotic production. In the case of two closely related and morphologically similar species, Chondrus crispus and Gigartina stellata, the former possesses considerable degrees of antimicrobial activity whilst the latter exhibits no such activity. The results also indicate that the production of antibiotics by the algae is affected by the season of the year.     

Granulation in thermophilic upflow anaerobic sludge blanket (UASB) reactors

The state of the art for thermophilic UASB reactors is discussed focusing on the start-up of UASB reactors, the influence of the waste water composition and temperature on the development and maintenance of thermophilic granules, and the microbial composition and structure of thermophilic granules.