Investigation of Nitrite Production Pathway in Integrated Partial Denitrification/Anammox Process via Isotope Labelling Technique and the Relevant Microbial Communities

In this study,the nitrogen removal performance of partial denitrificaiton/anammox(PDA)process was investigated by using an UASB reactor.High total nitrogen(TN)removal efficiency(91.97%)was achieved at an influent nitrogen loading rate of 0.64 kg/(m3·d).Anammox bacteria did execute the function of converting nitrate to nitrite in PDA system according to ^(15)N isotope labeling experiments and the contribution was approximately 36.3%.Candidatus_Brocadia,Candidatus_Kuenenia and Thauera were functional strains for anammox and denitrification process,respectively.Thauera and Candidatus_Brocadia were more important for TN removal at high loading rates(0.64 kg/(m3·d)).This result can provide a theoretical and technical foundation for the application of the PDA process.

Spatial patterns nitrogen transfer models of ectomycorrhizal networks in a Mongolian scotch pine plantation

Ectomycorrhizal(EM)networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer,seedling survival,internal cycling of nutrients,plant competition,and so on.To deeply their structure and function in ecosystems,we investigated the spatial patterns and nitrogen(N)transfer of EM networks usingN labelling technique in a Mongolian scotch pine(Pinus sylvestris var.mongolica Litv.)plantation in Northeastern China.In August 2011,four plots(20 × 20 m)were set up in the plantation.125 ml 5 at.%0.15 mol/LNHNOsolution was injected into soil at the center of each plot.Before and 2,6,30 and 215 days after theN application,needles(current year)of each pine were sampled along four 12 m sampling lines.Needle total N andN concentrations were analyzed.We observed needle N andN concentrations increased significantly over time afterN application,up to 31 and0.42%,respectively.There was no correlation between needle N concentration andN/N ratio(R2=0.40,n=5,P=0.156),while excess needle N concentration and excess needleN/N ratio were positively correlated across different time intervals(R~2=0.89,n=4,P\0.05),but deceased with time interval lengthening.NeedleN/N ratio increased with time,but it was not correlated with distance.NeedleN/N ratio was negative with distance before and 6th day and 30th day,positive with distance at 2nd day,but the trend was considerably weaker,their slop were close to zero.These results demonstrated that EM networks were ubiquitous and uniformly distributed in the Mongolian scotch pine plantation and a random network.We found N transfer efficiency was very high,absorbed N by EM network was transferred as wide as possible,we observed N uptake of plant had strong bias forN andN,namely N fractionation.Understanding the structure and function of EM networks in ecosystems may lead to a deeper understanding of ecological stability and evolution,and thus provide new theoretical approaches to improve conservation practices for the management of the Earth’s ecosystems.

Quantitative and Functional Phosphoproteomic Analysis Reveals that Ethylene Regulates Water Transport via the C-Terminal Phosphorylation of Aquaporin PIP2;1 in Arabidopsis

Ethylene participates in the regulation of numerous cellular events and biological processes, including wa- ter loss, during leaf and flower petal wilting. The diverse ethylene responses may be regulated via dynamic interplays between protein phosphorylation/dephosphorylation and ubiquitin/26S proteasome-mediated protein degradation and protease cleavage. To address how ethylene alters protein phosphorylation through multi-furcated signaling pathways, we performed a lSN stable isotope labelling-based, differential, and quantitative phosphoproteomics study on air- and ethylene-treated ethylene-insensitive Arabidopsis double loss-of-function mutant ein3-1/eill-1. Among 535 non-redundant phosphopeptides identified, two and four phosphopeptides were up- and downregulated by ethylene, respectively. Ethylene- regulated phosphorylation of aquaporin PIP2;1 is positively correlated with the water flux rate and water loss in leaf. Genetic studies in combination with quantitative proteomics, immunoblot analysis, protoplast swelling/shrinking experiments, and leaf water loss assays on the transgenic plants expressing both the wild-type and S280A/S283A-mutated PIP2;1 in the both Col-O and ein3eill genetic backgrounds suggest that ethylene increases water transport rate in Arabidopsis cells by enhancing S280/S283 phosphorylation at the C terminus of PIP2;1. Unknown kinase and/or phosphatase activities may participate in the initial up- regulation independent of the cellular functions of EIN3/EIL1. This finding contributes to our understanding of ethylene-regulated leaf wilting that is commonly observed during post-harvest storage of plant organs.

The effect of biochar on mycorrhizal fungi mediated nutrient uptake by coconut(Cocos nucifera L.)seedlings grown on a Sandy Regosol

Biochar amendment of soil may ameliorate inherently infertile soils,such as in the typical coconut(Cocos nucifera L.)growth areas along tropical coasts,where,moreover,temporary moisture stress commonly occurs.We conducted a pot experiment to evaluate the effects of biochar soil amendment(1%w/w)produced from Gliricidia sepium stems(BC-Gly)and rice husks(BC-RiH)on the growth of coconut seedlings and on N and P uptake mediated by mycorrhizae under wet or dry conditions in a Sandy Regosol.The pots were divided into root and hyphal zones by a nylon mesh,where 15N labelled N and P nutrients were only provided in the hyphal zone.Under wet conditions,biochar applica-tion did not affect plant growth,while under dry conditions,the BC-Gly increased root and plant growth similar to that under wet conditions.BC-Gly increased the acidic pH of the soil to a neutral level,and the microbial community shifted towards a higher fungal abundance.The P accumulated(Pacc)in roots was higher with BC-Gly and BC-RiH under dry and wet conditions,respectively.Pacc weakly correlated with the abundance of arbuscular mycorrhizal fungi(AMF)in the hyphal zone.With BC-Gly roots showed lower N derived from fertilizer.We conclude that biochar application has no impact on crop growth under wet conditions,while under dry conditions,BC-Gly stimulates crop growth and P uptake,probably through liming induced P availability but also possibly by some enhancement of AMF growth.The shift in the fungal-oriented microbial community and reduced plant fertilizer N uptake suggested that BC-Gly acted as an additional N source.