Simultaneous nitrification, denitrification, and phosphorus removal from nutrient-rich industrial wastewater using granular sludge

The biological removal of nitrogen and phosphorus from nutrient-rich abattoir wastewater using granular sludge has been investigated. A lab-scale sequencing batch reactor, seeded with granular sludge developed using synthetic wastewater, was operated for 13 months under alternating anaerobic and aerobic conditions. It is demonstrated that the granules could be sustained and indeed further developed with the use of abattoir wastewater. The organic, nitrogen, and phosphorus loading rates applied were 2.7 gCOD L(-1) day(-1), 0.43 gN L(-1) day(-1), and 0.06 gP L(-1) day(-1), respectively. The removal efficiency of soluble COD, soluble nitrogen and soluble phosphorus were 85%, 93%, and 89%, respectively. However, the high suspended solids in the effluent limited the overall removal efficiency to 68%, 86%, and 74% for total COD, TN, and TP, respectively. This good nutrient removal was achieved through the process known as simultaneous nitrification, denitrification, and phosphorus removal, likely facilitated by the presence of large anoxic zones in the center of the granules. The removal of nitrogen was likely via nitrite optimizing the use of the limited COD available in the wastewater. Accumulibacter spp. were found to be responsible for most of the denitrification, further reducing the COD requirement for nitrogen and phosphorus removal. Mineral precipitation was evaluated and was not found to significantly contribute to the overall nutrient removal. It is also shown that the minimum HRT in a granular sludge system is not governed by the sludge settleability, as is the case with floccular sludge systems, but likely by the limitations associated with the transfer of substrates in granules.     

The denitrification capability of cluster 1 Defluviicoccus vanus-related glycogen-accumulating organisms

The denitrification capability of Cluster 1 Defluviicoccus vanus-related glycogen-accumulating organisms (DvGAOs) is investigated. A sequencing batch reactor (SBR) fed with acetate as the sole carbon source was operated under alternating anaerobic-aerobic conditions to enrich Cluster 1 DvGAOs. Fluorescence in situ hybridization (FISH) showed that more than 85% of the bacterial population present in the reactor bound to the probes previously designed for Cluster 1 DvGAOs. A series of batch tests were performed to evaluate the capability of the community to reduce nitrate and nitrite. The tests were carried out both before and after the adaptation of the culture to anoxic conditions, and with both the intracellularly stored carbon and acetate as the electron donors. It was found that Cluster 1 DvGAOs were able to reduce nitrate but most likely unable to reduce nitrite. When un-adapted Cluster 1 DvGAOs were exposed to nitrate for the first time, a lag phase of approximately 4 h occurred, which was likely required for the synthesis of the necessary enzymes.     

Heterologous expression, and biochemical and cellular characterization of CaPLA1 encoding a hot pepper phospholipase A1 homolog

Phospholipid signaling has been recently implicated in diverse cellular processes in higher plants. We identified a cDNA encoding the phospholipase A1 homolog (CaPLA1) from 5-day-old early roots of hot pepper. The deduced amino acid sequence showed that the lipase-specific catalytic triad is well conserved in CaPLA1. In vitro lipase assays and site-directed mutagenesis revealed that CaPLA1 possesses PLA1 activity, which catalyzes the hydrolysis of phospholipids at the sn -1 position. CaPLA1 was selectively expressed in young roots, at days 4–5 after germination, and rapidly declined thereafter, suggesting that the expression of CaPLA1 is subject to control by a development-specific mechanism in roots. Because transgenic work was extremely difficult in hot peppers, in this study we overexpressed CaPLA1 in Arabidopsis so as to provide cellular information on the function of this gene. CaPLA1 overexpressors had significantly longer roots, leaves and petioles, and grew more rapidly than the wild-type plants, leading to an early bolting phenotype with prolonged inflorescence. Microscopic analysis showed that the vegetative tissues of 35S:CaPLA1 plants contained an increased number of small-sized cells, which resulted in highly populated cell layers. In addition, mRNAs for cell cycle-controlled proteins and fatty acid catabolizing enzymes were coordinately upregulated in CaPLA1 -overexpressing plants. These results suggest that CaPLA1 is functionally relevant in heterologous Arabidopsis cells, and hence might participate in a subset of positive control mechanisms of cell and tissue growth in transgenic lines. We discuss possible biochemical and cellular functions of CaPLA1 in relation to the phospholipid signaling pathway in hot pepper and transgenic Arabidopsis plants.     

北京市三个功能区空气微生物中值直径及粒径分布特征

空气中微生物对人类健康的危害除了与微生物的种类和浓度有关外,还与微生物粒子的大小密切相关,并且不同粒径的空气微生物对人们健康影响的作用机理不同。通过定点试验调查,运用国产安德森生物粒子取样器着重研究北京市3个功能区(文教区-中国科学院生态环境研究中心所在区域、交通干线-西直门和公园绿地-北京植物园)空气微生物的中值直径和粒径分布。结果表明,不同功能区空气微生物的粒径分布相同,空气细菌,真菌与放线菌的粒径分布各不相同。空气细菌粒径呈偏态分布,空气真菌呈对数正态分布,空气放线菌的分布特征与空气真菌相反,主要分布在>8.2μm和<2.0μm级中。不同属真菌的粒径分布也不相同,枝孢属、青霉属和曲霉属呈对数正态分布,链格孢属和无孢菌为偏态分布。空气细菌的中值直径明显大于空气真菌和放线菌。交通干线和公园绿地空气细菌和真菌粒子中值直径明显大于文教区,放线菌粒子中值直径交通干线明显高于文教区和公园绿地。空气微生物中值直径在一年各月中没有明显的变化规律。     

城市生态系统空气微生物群落研究进展

空气微生物是城市生态系统重要的生物组成部分 ,空气中广泛分布的细菌、真菌孢子、放线菌和病毒等生物粒子不仅具有极其重要的生态功能 ,还与城市空气污染 ,城市环境质量和人体健康密切相关。从生态系统角度出发 ,着重论述了城市微生物气溶胶的粒谱范围、空气微生物的主要类型、空气微生物浓度的时空变化和空气微生物群落结构的影响因素。综述结果表明 :城市微生物气溶胶的粒谱范围为 0 .0 0 2～ 30 μm;在调查的城市中 ,空气细菌有 2 1属 ,其中优势菌属为芽孢杆菌属 (Bacillus)、葡萄球菌属 (Staphylococcus)、微球菌属 (Micrococcus)和微杆菌属 (Microbacterium ) ,真菌有 2 1属 ,其中优势菌属为交链孢属(Alternaria)、青霉属 (Penicillium)、曲霉属 (Aspergillus)和木霉属 (Trichoderma) ,放线菌共有 7属 ;一年中冬季空气微生物浓度最低 ,一天中空气微生物浓度在 8:0 0～ 10 :0 0出现高峰 ,2 :0 0～ 4 :0 0或者 12 :0 0～ 14 :0 0出现低峰 ,交通干线和商业区空气微生物的浓度较高 ,公园绿地较低 ,并且随着高度的增加空气微生物浓度随之减少 ;污染因子 SO2 、NO2 、NO和环境因素风速风向、温度、相对湿度、光照、雨、雪等影响空气微生物的数量和浓度。在经济发达 ,人口流动较多的城市如北京、上海、广     

不同森林恢复类型对土壤微生物群落的影响

为了评价不同森林恢复类型与方式对南方红壤丘陵区退化生态系统土壤微生物群落的影响,借助氯仿熏蒸法、平板涂抹法和BIOLOG检测法,比较研究了4种森林恢复类型土壤微生物的群落特征．结果表明,4种森林恢复类型土壤微生物生物量碳、细菌数量差异显著,2项指标均以天然次生林土壤最高,人工林次之,荒地最差;碳源平均颜色变化率(AWCD法)和微生物代谢多样性指数(丰富度和多样性)在5种植被类型的土壤中也有明显差异,其趋势与微生物量碳、细菌数量基本相同;天然次生林土壤微生物群落利用碳源的整体能力和功能多样性比人工林和荒地强．相关分析表明,0～20和20～40cm土壤微生物的代谢多样性与根系生物量紧密相关(r=0．933,P<0．05;r=0．925,P<0．05)．自然恢复更有利于改善土壤微生物的结构和功能．     

Distractor Evoked Deviations of Saccade Trajectory Are Modulated by Fixation Activity in the Superior Colliculus: Computational and Behavioral Evidence

Previous studies have shown that saccades may deviate towards or away from task irrelevant visual distractors. This observation has been attributed to active suppression (inhibition) of the distractor location unfolding over time: early in time inhibition at the distractor location is incomplete causing deviation towards the distractor, while later in time when inhibition is complete the eyes deviate away from the distractor. In a recent computational study, Wang, Kruijne and Theeuwes proposed an alternative theory that the lateral interactions in the superior colliculus (SC), which are characterized by short-distance excitation and long-distance inhibition, are sufficient for generating both deviations towards and away from distractors. In the present study, we performed a meta-analysis of the literature, ran model simulations and conducted two behavioral experiments to further explore this unconventional theory. Confirming predictions generated by the model simulations, the behavioral experiments show that a) saccades deviate towards close distractors and away from remote distractors, and b) the amount of deviation depends on the strength of fixation activity in the SC, which can be manipulated by turning off the fixation stimulus before or after target onset (Experiment 1), or by varying the eccentricity of the target and distractor (Experiment 2).     

Bone marrow mesenchymal stem cells reduce ureteral stricture formation in a rat model via the paracrine effect of extracellular vesicles

With no effective therapy to prevent or treat ureteral stricture (US), a multifactorial fibrotic disease after iatrogenic injury of the ureter, the need for new therapies is urgent. Mesenchymal stem cells (MSCs) have been widely studied for treating tissue defects and excessive fibrosis, and recent studies established that one of the main therapeutic vectors of MSCs is comprised in their secretome and represented by extracellular vesicles (EVs). Thus, we have determined to explore the specific role of MSCs‐derived EVs (MSC‐EVs) treatment in a pre‐clinical model of US. The results firstly showed that either a bolus dose of MSCs or a bolus dose of MSC‐EVs (administration via renal‐arterial) significantly ameliorated ureteral fibrosis and recuperated ureter morphological development in a US rat model. We confirmed our observations through MSCs or MSC‐EVs treatment alleviated hydronephrosis, less renal dysfunction and blunted transforming growth factor‐β1 induced fibration. Due to MSC‐EVs are the equivalent dose of MSCs, and similar curative effects of transplantation of MSCs and MSC‐EVs were observed, we speculated the curative effect of MSCs in treating US might on account of the release of EVs through paracrine mechanisms. Our study demonstrated an innovative strategy to counteract ureteral stricture formation in a rat model of US.