温度、pH对非光合微生物菌群固碳效率的影响及其成因分析

CO2是主要的温室气体,也是地球上最丰富的碳源和可再生资源,本实验通过研究温度和pH对非光合固碳微生物固碳效率的影响,以期获得非光合固碳微生物适宜的固碳条件,并通过16SrDNA序列分析,研究了不同条件对固碳微生物群落结构的影响及其与固碳效率的相关性。结果表明,好氧／厌氧固碳微生物菌群生长的最适pH均在7左右。好氧固碳微生物菌群可在较大的温度范围（10℃-40℃）内良好生长,但其固碳速率在10℃左右时最高,之后微生物固碳速率随温度上升而下降,在40℃时,微生物固碳速率开始回升。厌氧时微生物的固碳效率随温度的变化情况与好氧时相似,但总体效果要比其在好氧时低20％～25％。由DGGE图谱及戴斯系数分析可得培养温度和pH对群落结构有显著影响,不同pH和温度条件下优势菌差异显著,这可能是固碳效率变化的重要原因之一。     

Enhanced CO2 fixation by a non-photosynthetic microbial community under anaerobic conditions: optimization of electron donors

To enhance the CO(2) fixation efficiency of the non-photosynthetic microbial community (NPMC) isolated from sea water under anaerobic conditions without hydrogen, the concentration of inorganic compounds as electron donors and their ratios were optimized by response surface methodology design (RSMD). The results indicated that the CO(2) fixation efficiency of NPMC using NaNO(2), Na(2)S(2)O(3) and Na(2)S as the electron donors was increased about 90%, 75% and 207%, respectively. Additionally, there were interactions between two electron donors and three electron donors. Central composite RSMD experimentation predicted that the optimal concentration and ratios of these inorganic compounds was 1.04% NaNO(2), 1.07% Na(2)S(2)O(3) and 0.98% Na(2)S. Under these conditions, the fixed CO(2) was 139.89 mg/L, which obviously exceeded the amount prior to optimization, as well as when H(2) was used as an electron donor. The established electron donor system can effectively enhance the CO(2) fixation efficiency of NPMC without hydrogen under anaerobic conditions.     

非光合固碳微生物菌群最佳组合氮源的正交实验分析

与光合微生物相比,非光合微生物固定CO2具有不用光照,可昼夜持续的优点.氮源是影响微生物固碳效率的重要因素.本研究围绕非光合固碳微生物培养中的氮源进行单因素实验,并在此基础上设计正交交互实验以确定最优的氮源组合.结果表明,实验中采用的三种无机氮对微生物固碳效率均有提升,其中( NH4)2SO4约在浓度为8g/L时达到最大值,NaNO3约在浓度为5 g/L时达到最大值而NaNO2约在浓度为5 g/L时达到最大值.根据单因素实验的结果设计L27(313)的正交交互实验表,得到不同氮源组合影响固碳效率的主次顺序:NaNO3和(NH4)2SO4是影响微生物固定CO2的主要因素,其余依次为NaNO3和(NH4)2SO4的交互作用,(NH4)2SO4和NaNO2的交互作用以及NaNO2等.同时三种氮源的最优组合为(NH4)2SO4浓度9 g/L,NaNO3浓度5 g/L和NaNO2浓度8 g/L,并得到三种因素影响的直观图.     

非光合微生物菌群好氧固定CO2的研究

微生物固定CO2在环境、资源方面具有重要意义.然而,通常具有较高固碳能力的光合细菌和氢-氧化细菌由于需要光照/严格厌氧和供氢,限制了其在反应器或土壤中的应用.本研究通过生物技术手段从海水及其沉积物中选育到在普通好氧条件下具有固碳能力的非光合微生物菌群,并通过电子供体和无机碳源结构的优化,显著提高了其对无机碳的同化能力,好氧条件下固碳菌液的最高无机碳同化效率可达110 mgCO2 / L·d,为实现普通环境条件下的微生物固碳奠定了基础.同时,通过分子生物学手段研究了不同环境条件下固碳微生物菌群的群落结构,以期为进一步优化固碳微生物群落结构,提升固碳效率提供理论依据.结果发现在不同培养条件下,菌群的群落结构发生了很大改变,表明不同条件下的固碳优势菌属于不同的种属,但通过测序、序列比对及构建系统发育树后发现,在已测序的16个显著条带中,11个是不可培养微生物,即其只能以共生方式存在,混合培养时,固定CO2的效果可能是多种菌共同作用的结果.这意味着单一纯种微生物的固碳效率可能较低,研究与优化固碳微生物菌群的结构和配比将有利于固碳效率的提升.     

非光合固碳微生物菌群的耐盐特性及其影响因素

从海洋中分离驯化得到的非光合固碳微生物菌群(NPMC)是无需光照和供氢的化能自养微生物,若能用于贫瘠盐碱地改良,实现其在盐碱土壤中的二次固碳,对于盐碱土壤的低碳化改良具有重要的意义.本实验初步验证了NPMC的耐盐特性,以及微量元素和磷酸盐缓冲液两单因素在次高盐条件下对NPMC固碳效率的影响.并通过响应面法研究了微量元素与盐浓度对NPMC固碳效率的交互作用.结果表明,非光合固碳微生物拥有耐受高盐浓度的特性,可耐受高达100g/L以上的总盐度,因此可用于重盐碱土壤的改良.微量元素和磷酸盐缓冲液浓度的增加,都可增强NPMC的固碳效率,微量元素的促进效应高于磷酸盐缓冲液.微量元素和盐度对NPMC固碳效率的影响存在交互作用.     

Effects of temperature and CO2 concentration on photosynthetic CO2 fixation by Chlorella

The rates of photosynthetic ¹⁴CO₂ fixation by Chlorella vulgarisllh, grown under high CO₂, were determined between 4 to 37°Cwith air containing from 300 to 13,000 ppm ¹⁴CO₂. When the CO₂level was increased, both the rate of photosynthesis and theoptimum temperature for maximum photosynthesis increased. Themaximum photosynthetic rate was reached at 12°C with 300ppm ^l4CO₂. Among the photosynthetic products fromed at 300 ppm ¹⁴CO₂, glycolatedecreased greatly when the temperature was raised from 20 to30°C. At 3,000 ppm ¹⁴CO₂ an insignificant amount of glycolatewas formed at all temperatures, whereas ¹⁴C-incorporation intothe insoluble fraction, sucrose, and the lipid fraction wassignificantly higher than at 300 ppm ¹⁴CO₂. The ¹⁴C in sucrosewas greatly increased and the radioactivity in the insolublefraction decreased when the temperature was raised from 28 to36°C. (Received April 8, 1980; )     

非光合固碳微生物的碳源组合优化

二氧化碳(CO_2)过量排放而引起的全球变暖是目前全球面临的重大环境问题。微生物固碳是实现二氧化碳资源利用的一种重要方式。探索无需光照的高效固碳微生物对于更广泛环境条件下的微生物固碳具有重要意义。在从全球各大海域筛选富集出非光合微生物茵群的基础上,本文构建了在不同的电子供体条件下(铵和氢气)促进非光合微生物茵群生长的最佳混合碳源组合,得到如下结果:在以NH_4~+为电子供体的条件下,优化后的碳源组合为374.24 mgC/L碳酸钠(Na_2CO_3),54.76 mgC/L碳酸氢钠(NaHCO_3)和0 mgC/LCO_2时,最佳响应值TOC为3.06 mg/L。最佳响应值TOC低于以Na_2CO_3为单一碳源时,但高于以CO_2或NaHCO_3为单一碳源时;在以H_2为电子供体条件下,使用优化后的混合碳源为0.26 mg/L Na_2CO_3、0.59mg/L NaHCO_3和71.48mL/L CO_2时,非光合微生物菌群的固碳效率可达27.62 mg/L,较以CO_2为单一碳源提高35%左右。这可能意味着有H_2条件下非光合微生物菌群中的微生物可能以羟基丙酸固碳途径为主,而且多条固碳途径均能被混合菌群利用。     

Comparison analysis on the energy efficiencies and biomass yields in microbial CO2 fixation

CO₂ fixation by a hydrogen-oxidizing bacterium, Cupriavidus necator, was evaluated in a packed bed bioreactor under a constant flow rate of gas mixtures (H₂, O₂, CO₂). The overall energy efficiency depends on the efficiencies of CO₂ fixation into carbohydrate and the reduced carbon into biomass and bioproducts, respectively. The efficiencies varied with the limiting gas substrate. Under O₂ limitation, the efficiency (20–30%) of CO₂ fixation increased with time and was higher than the overall efficiency (12–18%). Under H₂ limitation, the efficiency of CO₂ fixation declined with time while the biomass yield was quite similar to that under O₂ limitation. A cellular metabolic model was suggested for the lithoautotrophic growth of C. necator, including CO₂ fixation into carbohydrate followed by the main metabolic pathway of reduced carbon. Under CO₂ limitation, most H₂ energy was wasted, resulting in a very low biomass yield. Under a dual limitation of O₂ and nitrogen, biosynthesis of poly(3-hydroxybutyrate) was triggered, and the energy efficiency or yield of biopolyester was lower than those of microbial cell mass. Compared with a green microalga Neochloris oleoabundans that produces lipid under nutrient limitation, C. necator exhibited a much higher (3–6 times) energy efficiency in producing biomass and bioproducts from CO₂.     

中等嗜热细菌浸出黄铜矿过程中pH对群落结构的影响

为了优化浸出工艺,研究了pH对浸矿过程主要微生物种群结构的影响。用中度嗜热混合菌槽浸黄铜矿精矿,在不控制pH,控制pH为2．5及控制pH为1．2时,应用PCR-RFLP（限制性酶切片段长度多态性）方法对上述浸出条件下的细菌群落动态变化进行研究。结果表明,浸出体系只有两种微生物,一种为Acidithiobacillus Caldus,一种为Leptospirillum ferriphilum。pH对群落结构有明显影响。不控制pH时,浸出开始阶段At．caldus是优势种群,占群落的96％,随着浸出的进行,L．ferriphilum增多,在浸出后期代替At．caldus成为优势菌种,占69％。控制pH时,L．ferriphilum始终占主导地位,同时发现pH为2．5时At．caldus在群落中的丰度比pH为1．2时高。     

Control analysis of photosynthetic CO2 fixation

The potential of control analysis to aid our understanding of regulation and control of photosynthetic carbon metabolism is investigated. Methods of metabolic control analysis are used to determine flux control coefficients of photosynthetic reactions from enzyme elasticities. Equations expressing control coefficients symbolically by enzyme elasticities are derived, and general properties of these expressions are analysed. Suggestions for experimental determination of flux control coefficients from enzyme elasticities are given. A simplified model of the Calvin-Benson cycle is used to illustrate interrelations between patterns of photosynthetic metabolites and that of control coefficients.Abbreviations GAPDH glyceraldehyde phosphate dehydrogenase - PGA 3-phosphoglycerate - PGK 3-phosphoglycerate kinase - Pi inorganic phosphate - PRK phosphoribulokinase - RuBP ribulose-1,5-bisphosphate(_{total, free}) - Rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase - Ru5P ribulose-5-phosphate     

Influence of pH on enzyme stabilization: an analysis using a series-type mechanism

A series-type model is utilized to show the influence of pH on enzyme inactivation kinetics and stability. Examples of enzyme inactivations involving both single-step and series-type mechanisms are presented. Empirical relations for the inactivation rate constant for the first step and the residual activity as a function of pH are presented. This provides physical insights into the enzyme inactivation processes. The analysis forms the beginning of a framework within which one could quantitatively manipulate the inactivation rate constants and the residual activity for enzymes in desired directions as a function of pH.     

Influence of sulfide and temperature on species composition and community structure of hot spring microbial mats

In solfataric fields in southwestern Iceland, neutral and sulfide-rich hot springs are characterized by thick bacterial mats at 60 to 80 degrees C that are white or yellow from precipitated sulfur (sulfur mats). In low-sulfide hot springs in the same area, grey or pink streamers are formed at 80 to 90 degrees C, and a Chloroflexus mat is formed at 65 to 70 degrees C. We have studied the microbial diversity of one sulfur mat (high-sulfide) hot spring and one Chloroflexus mat (low-sulfide) hot spring by cloning and sequencing of small-subunit rRNA genes obtained by PCR amplification from mat DNA. Using 98% sequence identity as a cutoff value, a total of 14 bacterial operational taxonomic units (OTUs) and 5 archaeal OTUs were detected in the sulfur mat; 18 bacterial OTUs were detected in the Chloroflexus mat. Although representatives of novel divisions were found, the majority of the sequences were >95% related to currently known sequences. The molecular diversity analysis showed that Chloroflexus was the dominant mat organism in the low-sulfide spring (1 mg liter(-1)) below 70 degrees C, whereas Aquificales were dominant in the high-sulfide spring (12 mg liter(-1)) at the same temperature. Comparison of the present data to published data indicated that there is a relationship between mat type and composition of Aquificales on the one hand and temperature and sulfide concentration on the other hand.     

大气CO2浓度和气温升高对麦田节肢动物群落的影响

为了预测气候变化对麦田节肢动物群落多样性的影响, 本研究在麦田开放环境中设置4种处理, 分别是高温(高于当时气温2℃和当前CO₂浓度)、高CO₂浓度(500 μL/L和当时气温)、高温+高CO₂浓度和对照(当前CO₂浓度和气温)等, 采用定期随机抽样方法调查节肢动物群落的多样性, 用经典的多样性指数对整体节肢动物群落以及不同食性节肢动物群落多样性进行分析。共采到节肢动物3纲10目42科52种。仅“高温”和“高温+高CO₂”处理显著增大节肢动物群落的均匀度, 其余处理均无显著影响。“高温+高CO₂”处理的影响随小麦生长发育期不同而略有差异, 在苗期可增大Shannon-Wiener多样性指数, 而在后期使该指数减小; “高温+高CO₂”与“高温”处理的群落多样性较为相似。对不同食性节肢动物群落的分析表明, 与对照相比, 植食性昆虫群落在“高CO₂”下丰富度显著增大; 寄生性昆虫群落的多度在“高温”下显著增大; 腐食性等节肢动物群落的多度在“高CO₂+高温”和“高温”处理下有所增大、均匀度在“高温”下略降低, 但均未达统计上的显著水平; 捕食性节肢动物群落不受影响。本研究说明, CO₂浓度和气温升高不同程度地影响麦田节肢动物群落的物种多样性, 两类因素同时升高与各自单独升高的影响不完全一致。     

On the mechanism of autotrophic fixation of CO2 bychloroflexus aurantiacus

The activity of two carboxylating enzymes was studied in the green filamentous bacteriumChloroflexus aurantiacus. The carboxylation reaction involving pyruvate synthase was optimized using¹⁴CO₂ and cell extracts. Pyruvate synthase was shown to be absent from cells ofCfl. aurantiacus OK-70 and present (in a quantity sufficient to account for autotrophic growth) in cells ofCfl. aurantiacus B-3. Differences in the levels of acetyl CoA carboxylase activity were revealed between cells of the strains studied grown under different conditions. The data obtained confirm the operation of different mechanisms of autotrophic CO₂ assimilation inCfl. aurantiacus B-3 andCfl. aurantiacus OK-70: in the former organism, it is the reductive cycle of dicarboxylic acids, and in the latter one, it is the 3-hydroxypropionate cycle.     

Phenol and sulfide oxidation in a denitrifying biofilm reactor and its microbial community analysis

A microbial consortium attached onto a polyethylene support was used to evaluate the simultaneous oxidation of sulfide and phenol by denitrification. The phenol, sulfide and nitrate loading rates applied to an inverse fluidized bed reactor were up to 168 mg phenol–C/(l d), 37 mg S^2?/(l d) and 168 mg NO₃^?–N/(l d), respectively. Under steady state operation the consumption efficiencies of phenol, sulfide and nitrate were 100%. The N₂ yield (g N₂/g NO₃^?–N) was 0.89. The phenol was mineralized resulting in a yield of 0.82 g bicarbonate–C/g phenol–C and sulfide was completely oxidized to sulfate with a yield of 0.99 g SO₄^2?–S/g S^2?. 16S rRNA gene-based microbial community analysis of the denitrifying biofilm showed the presence of Thauera aromatica, Thiobacillus denitrificans, Thiobacillus sajanensis and Thiobacillus sp. This is the first work reporting the simultaneous oxidation of sulfide and phenol in a denitrifying biofilm reactor.     

Effects of long term CO2 enrichment on microbial community structure in calcareous grassland

Elevated CO₂ generally increases plant productivity, and has been found to alter plant community composition in many ecosystems. Because soil microbes depend on plant-derived C and are often associated with specific plant species, elevated CO₂ has the potential to alter structure and functioning of soil microbial communities. We investigated soil microbial community structure of a species-rich semi-natural calcareous grassland that had been exposed to elevated CO₂ (600 μL L^?1) for 6 growing seasons. We analysed microbial community structure using phospholipid fatty acid (PLFA) profiles and DNA fingerprints obtained by Denaturing Gradient Gel Electrophoresis (DGGE) of 16S rDNA fragments amplified by the Polymerase Chain Reaction (PCR). PLFA profiles were not affected by CO₂ enrichment and the ratio of fungal and bacterial PLFA did not change. Ordination analysis of DNA fingerprints revealed a significant relation between CO₂ enrichment and variation in DNA fingerprints in summer (P=0.01), but not in spring. This variation was due to changes in low-intensity bands, while dominant bands did not differ between CO₂ treatments. Diversity of the bacterial community, as assessed by number of bands in DNA fingerprints and calculation of Shannon diversity indices, was not affected by elevated CO₂. Overall, only minor effects on microbial community structure were detected, corroborating earlier findings that soil carbon inputs did probably change much less than suggested by plant photosynthetic responses.     

Influence of soil pollution on the composition of a microbial community

The abundance dynamics and composition of indigenous soil microbial communities were studied in soils polluted with naphthalene, dioctyl phthalate, diesel fuel, and crude oil. DGGE analysis of the 16S rRNA genes amplified from the total soil DNA revealed that the bacterial community of uncontaminated soil was more diverse and included no dominant species. In the soil samples polluted with the crude oil, diesel fuel, or dioctyl phthalate, Pseudomonas became the dominant bacteria since the third day of the experiment. In the soil polluted with naphthalene, two genera of bacteria (Pseudomonas and Paenibacillus) were dominant in population on the third day of the experiment, while on the 21th day of the experiment Arthrobacter became dominant. During the experiment, the average number of indigenous bacterial degraders increased approximately by two orders of magnitude. While the key genes of naphthalene catabolism, nahAc and nahH, were not detected in the pristine soil, they were found in a significant amount on the third day after naphthalene addition. Three degrader strains harboring the plasmids of naphthalene biodegradation (IncP-9 group) were isolated on the third day from the soil polluted with naphthalene. Two of these plasmids, although isolated from various degraders, were shown to be identical.