Biomass and nutrient productivities ofTetraselmis chuii under mixotrophic culture conditions with various C：N ratios

Mass microalgal culture plays an irreplaceable role in aquaculture,but microalgal productivity is restricted by traditional autotrophic culture conditions.In the present study,a Tetraselmis chuii strain belonging to the phylum Chlorophyta was isolated from south Yellow Sea.The growth rate and biomass productivity of this strain was higher under mixotrophic conditions with different carbon:nitrogen(C:N)ratios than those under autotrophic conditions.When the C:N ratio was 16,the optical density and biomass productivity were 3.7-and 5-fold higher than their corresponding values under autotrophic culture conditions,respectively.Moreover,T.chuii synthesized more polysaccharides and total lipids under mixotrophic conditions.In addition,T.chuii cultured under mixotrophic conditions synthesized more types of fatty acids than autotrophic culture conditions.At a C:N ratio of 16,the percentage of C16:0 and C18:1 reached 30.08%and 24.65%of the total fatty acid(TFA) content,respectively.These findings may provide a basis for largescale mixotrophic culture of T.chuii,as a potential bait-microalga.

Degeneration of photosynthetic capacity in mixotrophic plants, Chimaphila japonica and Pyrola decorata (Ericaceae)

The evolution of photosynthesis is an important feature of mixotrophic plants.Previous inferences proposed that mixotrophic taxa tend to retain most genes relating to photosynthetic functions but vary in plastid gene content.However,no sequence data are available to test this hypothesis in Ericaceae.To investigate changes in plastid genomes that may result from a transition from autotrophy to mixotrophy,the plastomes of two mixotrophic plants,Pyrola decorata and Chimaphila japonica,were sequenced at Illumina's Genome Analyzer and compared to the published plastome of the autotrophic plant Rhododendron simsii,which also belongs to Ericaceae.The greatest discrepancy between mixotrophic and autotrophic plants was that ndh genes for both P.decorata and C.japonica plastomes have nearly all become pseudogenes.P.decorata and C.japonica also retained all genes directly involved in photosynthesis under strong selection.The calculated rate of nonsynonymous nucleotide substitutions and synonymous substitutions of protein-coding genes(dN/dS) showed that substitution rates in shade plants were apparently higher than those in sunlight plants.The two mixotrophic plastomes were generally very similar to that of non-parasitic plants,although ndh genes were largely pseudogenized.Photosynthesis genes under strong selection were retained in the two mixotrophs,however,with greatly increased substitution rates.Further research is needed to gain a clearer understanding of the evolution of autotrophy and mixotrophy in Ericaceae.

Growth and Physiological Features of Cyanobacterium Anabaena sp. Strain PCC 7120 in a Glucose-Mixotrophic Culture

Mixotrophic growth is one potential mode for mass culture of microalgae and cyanobacteria particularly suitable for the production of high value bioactive compounds and fine chemicals.The typical heterocystous cyanobacterium Anabaena sp.PCC 7120 was grown in the presence of exogenous glucose in light.Glucose improved the cell growth evidently,the maximal specific growth rate under mixotrophic condition（0.38 d 1）being 1.6-fold of that of photoautotrophic growth.Mixotrophy caused a variation in cellular pigment composition,increasing the content of chlorophyll a and decreasing the contents of carotenoid and phycobiliprotein relative to chlorophyll a.Fluorescence emission from photosystem II（PSII）relative to photosystem I was enhanced in mixotrophic cells,implying an increased energy distribution in PSII.Glucokinase（EC 2.7.1.2）activity was further induced in the presence of glucose.The mixotrophic culture was scaled up in a 15 L airlift photobioreactor equipped with an inner and an outer light source.A modified Monod model incorporating the specific growth rate and the average light intensity in the reactor was developed to describe cell growth appropriately.The understanding of mixotrophic growth and relevant physiological features of Anabaena sp.PCC 7120 would be meaningful for cultivation and exploitation of this important cyanobacterial strain.

Mixotrophic Cultivation of Tetraselmis sp.-1 in Airlift Photobioreactor

Tetraselmis sp.-1 is a new microalgae strain constructed by cell fusion technique. In this paper, the mixotrophic cultivation of Tetraselmis sp.-1 in airlift photobioreactor is investigated. Firstly, the paper calculates the light attenuation in the mixotrophic medium, and sets the light attenuation model. Secondly, it uses the same dissolved oxygen coefficient (K d) of flask culture to select the aeration of bioreactor. Finally, it sets the growth kinetic model, production (chlorophyll-a and total lipid) kinetic models and substrate (glucose) consumption kinetic model of Tetraselmis sp.-1 in airlift photobioreactor.

黄铁矿基MFC-CW耦合系统反硝化动力学研究

研究比较了黄铁矿基双阳极MFC-CW在不同碳氮比(0和2.5)及初始硝酸盐浓度(7、14和28 mg/L)条件下上阳极和下阳极的反硝化速率,以及对不同阶段硝酸盐还原反应动力学的模拟,从动力学角度揭示系统自养-异养协同反硝化机理。结果显示:不同碳氮比下系统两阳极硝酸盐还原效果差异不大,而亚硝酸盐累积、硫酸盐生成的差别较大,两阳极处微生物群落组成相似,优势菌属的相对丰度受C/N、阳极位置影响较大;两阳极处的硝酸盐还原动力学均属于一级反应,且C/N=0时反硝化速率常数(0.0087、0.0045和0.0188/h)均小于C/N=2.5(0.0151、0.0071和0.0798/h;以上阳极为例);MFC-CW系统的反硝化动力学更符合Monod-CSTR模型,且在停留时间较长时取得更好的拟合效果,随着停留时间的增加,C/N=0时系统的反硝速率增加,C/N=2.5时系统的反硝化速率在一定范围内波动[0.6662—0.7744 g/(m^(2)·d)]。实验结果可为黄铁矿基MFC-CW的实际工程应用提供理论指导。

Thiosulfate oxidation and autotrophy potential by marine prevalent heterotrophic bacteria of genus Marinobacter

The genus Marinobacter is very broadly distributed in global environments and is considered as aerobic heterotroph.In this study,six Marinobacter strains were identified with autotrophic thiosulfate oxidation capacity.These strains,namely Marinobacter guineae M3B^(T),Marinobacter aromaticivorans D15-8PT,Marinobacter vulgaris F01^(T),Marinobacter profundi PWS21^(T),Marinobacter denitrificans JB02H27T,and Marinobacter sp.ST-1M(with a 99.93%similarity to the 16S rDNA sequences of Marinobacter salsuginis SD-14B^(T)),were screened out of 32 Marinobacter strains by autotrophic thiosulfate oxidization medium.The population of cells grew in a chemolithotrophic medium,increasing from 105 cells/mL to 10^(7) cells/mL within 5 d.This growth was accompanied by the consumption of thiosulfate 3.59 mmol/L to 9.64 mmol/L and the accumulation of sulfate up to 0.96 mmol/L,and occasionally produced sulfur containing complex particles.Among these Marinobacter strains,it was also found their capability of oxidizing thiosulfate to sulfate in a heterotrophic medium.Notably,M.vulgaris F01^(T)and M.antarcticus ZS2-30^(T)showed highly significant production of sulfate at 9.45 mmol/L and 3.10 mmol/L.Genome annotation indicated that these Marinobacter strains possess a complete Sox cluster for thiosulfate oxidation.Further phylogenetic analysis of the soxB gene revealed that six Marinobacter strains formed a separate lineage within Gammaproteobacteria and close to obligate chemolithoautotroph Thiomicrorhabdus arctica.The results indicated that thiosulfate oxidizing and chemolithoautotrophic potential in Marinobacter genus,which may contribute to the widespread of Marinobacter in the global ocean.

PHBV-硫铁矿基人工湿地处理实际污水处理厂尾水混合营养反硝化研究

以河南省新乡市某大型污水处理厂尾水为研究对象,开展模拟人工湿地尾水深度脱氮除磷研究。选用聚羟基丁酸戊酸酯(PHBV)和硫铁矿作为湿地系统的主要功能填料,构建异养反硝化与自养反硝化相结合的混合营养反硝化系统。通过水质指标监测和高通量测序等手段,探究工艺运行效果与微生物群落结构机制。构建PHBV+硫铁矿组(实验组)和PHBV+陶粒组(对照组),反应器连续运行77天,结果表明,当水力停留时间(HRT)为2小时,进水水质为NO_(3)^(−)-N=8.39±1.72 mg/L,TN=10.41±1.58 mg/L,TP=0.37 mg/L,COD=15.7 mg/L时,平均出水TN浓度达到2.22 mg/L,TP浓度达到0.28 mg/L,COD浓度为32.7 mg/L,PHBV+硫铁矿组人工湿地脱氮效率(78.55%)明显优于PHBV+陶粒组(51.25%),基本上达到地表水环境质量标准(GB 3838—2002)V类。微生物群落结构分析表明,PHBV+硫铁矿组人工湿地中的优势菌属为自养菌Desulfobacter和异养菌unclassified_k__norank_d__Bacteria,丰度分别为23.98%和12.30%,通过自养与异养菌的协同,实现混合营养反硝化,其中与硫代谢相关Desulfobacter主导的自养反硝化在系统脱氮中可能起主要作用。研究结果可为PHBV+硫铁矿基人工湿地尾水生物脱氮除磷的工程实践提供参考。

Isolation and characterization of facultative mixotrophic ammonia-oxidizing bacteria from constructed wetlands

Autotrophic ammonia-oxidizing bacteria （AOB） have been widely studied in constructed wetlands systems, while mixotrophic AOB have been less thoroughly examined. Heterotrophic bacteria were isolated from wastewater and rhizospheres of macrophytes of constructed wetlands, and then cultivated in a mixotrophic medium containing ammonium and acetic acid. A molecular characterization was accomplished using ITS-PCR amplification, and phylogenetic analysis based on 16S rRNA gene Sequences. Results showed the presence of 35 bacteria, among 400 initially heterotrophic isolates, that were able to remove ammonia. These 35 isolates were classified into 10 genetically different groups based on ITS pattern. Then, a collection of 10 isolates were selected because of their relatively high ammonia removal efficiencies （ARE≥ 80%） and their phylogenetic diversity. In conditions of mixotrophy, these strains were shown to be able to grow （increase of optical density OD660 during incubation with assimilation of nitrogen into cellular biomass） and to oxidize ammonia （important ammonia oxidation efficiencies, AOE between 79% and 87%）. Among these facultative mixotrophic AOB, four isolates were genetically related to Firmicutes （Bacillus and Exiguobacterium）, three isolates were affiliated to Actinobacteria （Arthrobacter） and three other isolates were associated with Proteobacteria （Pseudomonas, Ochrobactrum and Bordetella）.

以陶粒硫磺为填料的混合营养反硝化脱氮效能探究

为进一步降低城市污水处理厂出水的氮含量,实验设计了硫自养与异养混合营养反硝化体系,实验将陶粒和硫磺混合,共设置了7个不同的组合F0~F6,硫磺在F0~F6中的占比分别为0、1/6、2/6、3/6、4/6、5/6、6/6,其中F0为异养反硝化对照组,F1~F6为实验组。实验结果表明,实验组中F1、F2的脱氮效果较好,总氮去除率依次为89.96%和93.03%,分别接近和超过F0,且F1、F2相对于F0,体系的pH更加稳定;实验结束时,F1、F2两组的生物量分别为30.32、27.67 nmolP/g,低于F0,若各组的生物代谢速率相同,则F1、F2分别要比F0减少11.4%和19.2%的污泥量,认为F1和F2两种陶粒硫磺比例适合用于硫自养与异养反硝化的耦合,F1、F2中的硫磺占比分别为1/6和2/6,即陶粒∶硫磺(体积比)分别等于5:1和2:1。

硫自养-异养协同反硝化技术的研究进展

介绍了硫自养-异养协同反硝化技术的基本特性,传统的异养反硝化运行成本高、污泥产量大,而硫自养反硝化存在脱氮效率低、消耗碱度等缺点,将两种工艺耦合可以实现取长补短。硫自养-异养协同反硝化技术是处理低C/N比废水最具潜力和经济效益的工艺之一,具有成本低、SO_(4)^(2-)产量少、pH稳定、高效脱氮等优点,对其协同机理、微生物群落特征和影响因素进行阐述,例举了该工艺在城市尾水、地下水等低碳氮比废水等方面的实际应用,总结现阶段存在的问题并对未来研究方向进行展望,为该技术的推广和实际应用提供理论参考。

基于碳纤维强化的Fe^(0)混养反硝化脱氮效能与机制

以含NO_(3)^(-)-N合成废水为处理对象,对比了单独投加Fe^(0)与碳纤维强化Fe^(0)混养反硝化连续流反应器反硝化脱氮的效能。结果表明,在COD/NO_(3)^(-)-N为2.9~3.1、水力停留时间(HRT)为24 h时,投加碳纤维强化Fe^(0)的实验组R1对TN和NO_(3)^(-)-N平均去除率分别高达89.04%和97.13%,显著高于单独投加Fe^(0)的对照组R0。胞外聚合物(EPS)及电子传递活性(ETSA)变化规律表明,碳纤维的投入可进一步促进EPS生成,且强化了微生物对电子的利用率。扫描电镜-能量色散光谱仪(SEM-EDS)和X射线衍射仪(XRD)分析结果发现R1中Fe^(0)表面有明显的微生物腐蚀现象,FeO(OH)和含铁有机复合物是主要的腐蚀产物。微生物学分析表明,有机碳源投加量的提高及碳纤维的投加有效提高铁自养反硝化菌属丰度,促进反硝化功能基因的富集。

Woodchip-sulfur packed biological permeable reactive barrier for mixotrophic vanadium(V)detoxification in groundwater

Groundwater vanadium(V)(V(V))contamination is ubiquitous in vanadium mining/smelting region and development of novel strategy for its remediation is of particular significance.Herein woodchip-sulfur packed biological permeable reactive barrier(bio-PRB)is established towards successful V(V)bio-detoxification.V(V)removal was accelerated under such mixotrophic condition,compared with heterotrophic and autotrophic V(V)reductions.The performance of bio-PRB was relatively steady with V(V)removal efficiency of 68.5%–98.2%under fluctuant geochemical and hydrodynamic conditions.Microbial community analysis indicated that heterotrophic Geobacter was the main reducer to convert V(V)to insoluble V(IV),by consumption of organic source attributed to woodchip hydrolysis and sulfur anabolism of autotrophs(e.g.,Sulfuricurvum and Thiobacillus).V(V)reduction and elemental sulfur oxidation were regulated by genes as omcA,omcB and mtrC and soxB,respectively.The elevated contents of cytochrome c and nicotinamide adenine dinucleotide implied that improved electron transfer facilitated V(V)reduction.This study provides a cost-effective,robust and sustainable route for V(V)-polluted aquifer remediation.

Microalgal bioremediation of food-processing industrial wastewater under mixotrophic conditions： Kinetics and scaleup approach

The Chlorella microalgae were mixotrophically cultivated in an unsterilized and unfikered raw foodprocessing industrial wastewater. Both inorganic carbon （CO2-air） and organic carbon （wastewater） were provided simultaneously for microalgae growth. The aim of the study is to find out the utilization rates of total organic carbon （TOC） and chemical oxygen demand （COD） under mixotrophic conditions for a given waste water. About 90% reduction in TOC and COD were obtained for all dilutions of wastewater. Over 60% of nitrate and 40% of phosphate were consumed by microalgae from concentrated raw wastewater. This study shows that microalgae can use both organic and inorganic sources of carbon in more or less quantity under mixotrophic conditions. The growth of microalgae in food-processing industrial wastewater with all studied dilution factors, viz. zero （raw）, 1.6 （dilution A）, and 5 （dilution B） suggests that the freshwater requirement could be reduced substantially （20%-60%）. The degradation kinetics also suggests that the microalgae cultivation on a high COD wastewater is feasible and scalable.

混合营养脱氮在低C/N工业废水处理中的研究进展

富氮工业废水中难降解的氮杂环化合物加剧了碳氮比失衡,抑制了生物脱氮工艺中硝化反硝化过程,因而探究新型处理工艺是高效处理低C/N工业废水的必由之路。混合营养脱氮技术结合异养脱氮和自养脱氮的代谢路径,优化低C/N工业废水脱氮性能,进而实现低C/N工业废水处理提质增效。本文综述了混合营养脱氮工艺中铁介导生物脱氮、硫介导生物脱氮和菌藻共生脱氮工艺的作用机理、研究进展与影响因素,阐述了三种工艺特点及不同类型低C/N工业废水的适用性,并就三种混合营养脱氮工艺中存在的问题并结合当前研究方向,从优化电子供受体和代谢路径的角度提出增大电子容量、提高电子转移速率,结合电化学体系与Fe-S耦合增强协同代谢从而提升污染物代谢性能的建议。

两组混养反硝化滤池深度脱氮效果的对比试验

针对污水处理厂面对提标改造进一步提高深度脱氮问题,开展了以单一硫磺(1号)、硫磺-牡蛎壳(2号)为填料的两组硫混养反硝化滤池深度脱氮的对比试验。试验期间,2号滤池深度脱氮效果在各阶段均优于1号滤池;1号滤池在水温15~18℃、进水氮负荷为7.3×10-3kg/(m^(3)·d)、HRT=3.5 h时平均出水TN浓度为4.22 mg/L,TN去除率达到43.42%,同样条件,2号滤池平均出水TN浓度为3.42 mg/L,平均TN去除率达到54.49%,均可以稳定达到《大清河流域水污染物排放标准》(DB13/2795-2018)核心控制区标准,为试验期间最佳运行参数;牡蛎壳提供了大量碱度,使2号滤池pH降幅小于1号滤池,有效缓解了水体酸化;通过成本分析测算,将2号滤池与污水处理厂深度处理单元进行对比,前者吨水处理成本较后者降低了0.191元,具有很大的成本优势。

雨生红球藻混合营养与异养培养研究

研究雨生红球藻混合营养生长与异养生长对碳源及碳源浓度的需求，并对两种生长型进行比较。结果表明，乙酸钠较葡萄糖等其他碳源更能维持红球藻进行混合营养生长与异养生长。红球藻混合营养型生长与异养型生长的适宜乙酸钠浓度范围分别是０．５～１．０ｇ／Ｌ和１～１．５ｇ／Ｌ。混合营养型及异养型的平均生长速率分别是０．７２ｄ~－１和０．５３ｄ~－１，培养８ｄ的细胞干重分别是０．６５ｇ／Ｌ和０．３２ｇ／Ｌ。与光养型（对照）相比，混养型的各种生长指标均明显提高，异养型则下降。

兼养同步脱硫反硝化工艺及影响因素

应用厌氧附着生长反应器,采用兼养同步脱硫反硝化工艺,以硝酸盐和亚硝酸盐作为电子受体,处理含有硫化物和有机物的模拟废水.结果表明,进水硫化物与有机物浓度分别为200,20mg/L时,其去除率分别可达99.9%和80.5%.同时,引入的电子受体硝酸盐和亚硝酸盐的去除率分别为83.0%和94.5%.利于兼养脱硫反硝化的葡萄糖负荷与醋酸钠负荷分别为50,25mg/(L?d),葡萄糖对兼养状态下自养脱硫反硝化的抑制作用小于醋酸钠.

有机碳源对产EPA微藻(Nannochloropsis sp.)生长及光合作用的影响

研究了几种有机碳源对Nannochloropsis sp.生长及光合作用的影响. 结果表明,Nannochloropsis sp.具有混合营养生长的能力,葡萄糖对其生长有明显的促进作用,乙醇对藻细胞的生长有一定的促进作用,乙酸钠不能促进其生长,而乙酸、草酸、甘氨酸则抑制其生长. 在含30 mmol/L葡萄糖的培养基中培养8 d后,该藻细胞生长的最大生物量干重可达550 mg/L,是光自养培养条件下(最大生物量干重为392 mg/L)的1.4倍. 通过测定该藻细胞的光合放氧速率发现,该藻细胞在自养和混养条件下,最大净光合放氧速率几乎不变,混养条件下的暗呼吸速率、光补偿点高于自养条件,而光饱和点低于自养条件.

有机碳化合物对鱼腥藻7120生长的影响

在培养基中添加多种有机碳化合物对鱼腥藻 71 2 0进行培养。结果表明 ,葡萄糖的存在能明显地促进细胞的生长 ,但细胞仅能有限地利用葡萄糖 ;细胞混合营养生长的饱和光强约为 80 μEm- 2 s- 1 。乙酸、蔗糖、乙醇和甘油对细胞生长的影响不很显著 ,乳酸、柠檬酸、谷氨酸和甘氨酸表现出明显的抑制作用。鱼腥藻 71 2 0不能利用葡萄糖进行化能异养生长和光激活的化能异养生长 ,但有轻微的光异养现象。

营养方式对小球藻生长性能及营养价值的影响

分别对小球藻Chlorellasp.2003ZGH023进行光合自养、混合营养高碳、混合营养低碳和异养低碳培养,探讨不同营养方式对小球藻生长及细胞营养组成的影响。结果表明,在基础培养基中添加有机碳源,可显著提高小球藻的细胞密度和生物量,其中异养低碳组细胞密度可达54.73×106cell/ml,生物量6.86 g(dw)/L,且混合营养和异养小球藻细胞体积变大。在细胞营养组成上,与自养小球藻细胞相比,异养培养的小球藻细胞内蛋白含量显著下降而脂肪含量显著增加。光合自养组、混合营养高碳组、混合营养低碳组和异养组小球藻细胞粗蛋白含量分别是41.88%±0.14%、24.60%±0.07%、21.93%±0.13%和12.91%±0.35%。不同营养方式下小球藻的氨基酸总量变化与其粗蛋白含量的变化趋势相一致,光合自养组>混合营养高碳组>混合营养低碳组>异养组。小球藻总脂肪含量最高的为混合营养高碳组(15.32%±1.58%)和异养低碳组(14.15%±0.93%),显著高于混合营养低碳组(12.35%±0.25%)和光合自养组(10.04%±0.39%)。小球藻的脂肪酸组成会随着营养方式的改变而改变,光合自养组小球藻的主要脂肪酸为18∶3n3和14∶1,混合营养组小球藻的主要脂肪酸为14∶1和18∶1n9,异养低碳组中小球藻的主要脂肪酸为18∶1n9和16∶0。