Enzymatic determination of the autotrophic fixation of carbon dioxide in aerobic and anaerobic ecosystems]

An enzymatic method is suggested for determining the role of chemoautotrophs in bacterial populations of a high density. The method involves an assay of the activity of ribulose-1,5-diphosphate carboxylase, the key enzyme in autotrophic assimilation of carbon dioxide. The chemoautotrophic activity of microorganisms is rather high in ecosystems based on decomposition of organic matter in both aerobic and anaerobic conditions.     

Modeling of carbon dioxide mass transfer behavior in attached cultivation photobioreactor using the analysis of the pH profiles

The CO₂ mass transfer model associated with growth kinetics of microalgal biofilm in attached cultivation photobioreactor was developed and verified by using the analysis of pH profiles which were in equilibrium with inorganic carbon components concentrations (CO₂, H₂CO₃, HCO₃ ⁻ and CO₃ ²⁻) in medium. Model simulation results showed that the model well presented the biofilm growth process. The overall volumetric mass transfer coefficient of CO₂ was more influenced by CO₂ concentration in aerated gas but less by gas aeration rate and medium circulation rate. Other bio-kinetic parameters related with the microalgal biofilm such as CO₂ diffusion coefficient in biofilm, Monod maximum utilization rate of CO₂, lag phase duration of biofilm and half-saturation CO₂ concentration in the biofilm were independent on operational conditions. The pH profiles provided a way to monitor the variations of inorganic carbon concentrations of medium and to regulate the cultivation of attached microalgal biofilm by CO₂ supplement.

     

Detection of the microbial activity of aerobic heterotrophic, anoxic heterotrophic and aerobic autotrophic activated sludge organisms with an electrochemical sensor

The microbial activity of aerobic heterotrophic, anoxic heterotrophic and aerobic autotrophic microorganisms in biological wastewater treatment was determined by means of an electrochemical bioactivity sensor. The development of the sensor resulted in a system which can determine the microbial activities that are relevant for effective wastewater treatment. The signals of the sensor system are proportional to the substrate degradation and it can show inhibiting effects on the biomass. The most important advantages of the system are: it is independent of O₂ consumption, the three most important types of metabolic activities in wastewater technology can be measured with one sensor, furthermore the measurement is suitable for automation and it is on-line. The result is a potential for the optimization of processes based on microbial activity.     

Oxygen uptake during running as related to body mass in circumpubertal boys: a longitudinal study

To investigate the effect of endurance training on physiological characteristics during circumpubertal growth, eight young runners (mean starting age 12 years) were studied every 6 months for 8 years. Four other boys served as untrained controls. Oxygen uptake (VO2) and blood lactate concentrations were measured during submaximal and maximal treadmill running. The data were aligned with each individual's age of peak height velocity. The maximal oxygen uptake (VO2max; ml.kg-1.min-1) decreased with growth in the untrained group but remained almost constant in the training group. The oxygen cost of running at 15 km.h-1 (VO2 15, ml.kg-1.min-1) was persistently lower in the trained group but decreased similarly with age in both groups. The development of VO2max and VO2 15 (l.min-1) was related to each individual's increase in body mass so that power functions were obtained. The mean body mass scaling factor was 0.78 (SEM 0.07) and 1.01 (SEM 0.04) for VO2max and 0.75 (SEM 0.09) and 0.75 (SEM 0.02) for VO2 15 in the untrained and trained groups, respectively. Therefore, expressed as ml.kg-0.75.min-1, VO2 15 was unchanged in both groups and VO2max increased only in the trained group. The running velocity corresponding to 4 mmol.l-1 of blood lactate (nu la4) increased only in the trained group. Blood lactate concentration at exhaustion remained constant in both groups over the years studied. In conclusion, recent and the present findings would suggest that changes in the oxygen cost of running and VO2max (ml.kg-1.min-1) during growth may mainly be due to an overestimation of the body mass dependency of VO2 during running.(ABSTRACT TRUNCATED AT 250 WORDS)     

Response of soil carbon dioxide fluxes,soil organic carbon and microbial biomass carbon to biochar amendment: a meta‐analysis

Biochar as a carbon‐rich coproduct of pyrolyzing biomass, its amendment has been advocated as a potential strategy to soil carbon (C) sequestration. Updated data derived from 50 papers with 395 paired observations were reviewed using meta‐analysis procedures to examine responses of soil carbon dioxide (CO₂) fluxes, soil organic C (SOC), and soil microbial biomass C (MBC) contents to biochar amendment. When averaged across all studies, biochar amendment had no significant effect on soil CO₂ fluxes, but it significantly enhanced SOC content by 40% and MBC content by 18%. A positive response of soil CO₂ fluxes to biochar amendment was found in rice paddies, laboratory incubation studies, soils without vegetation, and unfertilized soils. Biochar amendment significantly increased soil MBC content in field studies, N‐fertilized soils, and soils with vegetation. Enhancement of SOC content following biochar amendment was the greatest in rice paddies among different land‐use types. Responses of soil CO₂ fluxes and MBC to biochar amendment varied with soil texture and pH. The use of biochar in combination with synthetic N fertilizer and waste compost fertilizer led to the greatest increases in soil CO₂ fluxes and MBC content, respectively. Both soil CO₂ fluxes and MBC responses to biochar amendment decreased with biochar application rate, pyrolysis temperature, or C/N ratio of biochar, while each increased SOC content enhancement. Among different biochar feedstock sources, positive responses of soil CO₂ fluxes and MBC were the highest for manure and crop residue feedstock sources, respectively. Soil CO₂ flux responses to biochar amendment decreased with pH of biochar, while biochars with pH of 8.1–9.0 had the greatest enhancement of SOC and MBC contents. Therefore, soil properties, land‐use type, agricultural practice, and biochar characteristics should be taken into account to assess the practical potential of biochar for mitigating climate change.     

Changes in carbon,nitrogen and phosphorus levels due to deforestation and cultivation: A case study in Simlipal National Park,India

The study area, within the Simlipal National Park, India, provides a rare variety of soil sampling sites. These include virgin forests in the proximity of several cultivated areas (where no chemical fertilizers or any modern technology has been used and where periods of cultivation vary from 5 to a little over 100 yr); samples from evergreen forests, deciduous forests and natural grasslands could also be obtained. The availability of numerous such samples made it possible to use statistical methods to evaluate the changes. This study showed that deforestation and cultivation result in statistically significant (P_0.05) reduction in organic C, total N and C:N ratios but no significant changes in total and available P levels; C:P and N:P ratios are also reduced. Loss of organic C and N occurs rapidly in the first 15 yr of cultivation and reaches quasi-steady state values around 1–2% organic C and 0.1–0.2% total N; extent of reduction is not related to initial levels. Significant reduction in C:N, C:P ratios following cultivation suggest that mineralisation losses of C are higher than loss of N whereas loss of P is lowest. Lack of significant correlation between organic C and P levels in all types of soils, suggests that the bulk of the P is in the inorganic form. Highest levels of organic C and N were observed in evergreen forests followed by deciduous forests, grasslands and cultivated areas in that order; total and available P levels, however, showed no significant differences. Evergreen vegetative cover appears to provide the ideal environment for organic matter accumulation.     

Oxygen and carbon dioxide transport by the haemocyanin of an amphibious crab,Holthuisana transversa

Summary The oxygen and carbon dioxide transporting properties of the haemolymph from an amphibious Australian crab,Holthuisana transversa were investigated. Within the temperature range 15 to 35°C increasing temperature markedly decreased oxygen affinity (H=–54 kJ·mol^–1). The Bohr effect was small at all temperatures with a mean value of –0.13. Over the temperature range 15–35°C there was a significant increase in the cooperativity of oxygen binding. Changing the concentration of Ca,l-lactate or haemocyanin in the haemolymph could elicit no significant change in either O₂ affinity or cooperativity of O₂ binding. There was no evidence in support of a specific effect of CO₂ on oxygen affinity of either non-dialysed or dialysed haemolymph.The amount of CO₂ that could be carried byH. transversa haemolymph was significantly reduced by increased temperature (approx. 14 to 12.5 mmol·l^–1 CO₂). Comparisons of oxygenated and deoxygenated haemolymph at a fixed pH were unable to demonstrate the presence of a significant Haldane effect. Combining data from oxygenated and deoxygenated haemolymph the buffer value was calculated to be in the range –6.2 to –8.5 mmol·l^–1 HCO ₃ ^– ·pH unit^–1.The insensitivity ofH. transversa haemocyanin function to all modulating influences except temperature is discussed with respect to the ecology of this crab.     

草甸草原土壤碳/氮矿化潜力及土壤微生物水分敏感性对极端干旱的响应

土壤碳、氮矿化是生态系统养分循环的关键过程,受到水分供给的强烈影响。本研究对极端干旱处理(连续3年生长季减少66%降水)的内蒙古草甸草原野外取土,采用超低温冻干后再调节土壤水分至3%、8%、13%、18%、25%和35% 6个水平进行室内培养,研究极端干旱处理后土壤碳/氮矿化潜力以及土壤微生物对水分变化的敏感性。结果表明: 与对照(自然降雨)相比,极端干旱处理后,6个培养水平的平均土壤氮矿化潜力显著提高14.2%,但未显著影响土壤碳矿化潜力。极端干旱显著提高土壤微生物生物量氮和土壤可溶性有机碳26.8%和26.9%。无论是对照还是极端干旱处理,土壤氮矿化潜力、碳矿化潜力和微生物生物量碳和氮均随着土壤含水量增加而增加,而可溶性有机碳从较低水分的培养水平(3%和8%)到较高水分的培养水平(>13%)显著降低,表明底物的扩散起到重要作用。极端干旱处理显著提高了碳矿化初始脉冲强度,表明极端干旱提高了土壤微生物对水分的敏感性。极端干旱显著降低了土壤碳矿化潜力/氮矿化潜力的比值,表明长期干旱可能会降低土壤碳、氮循环过程的耦合作用。极端干旱对土壤碳矿化和氮矿化过程的影响存在差异,激发了土壤微生物对水分的敏感性,弱化了碳、氮循环过程的耦合关系,并进一步影响中国北方草甸草原生态系统的生物地球化学循环过程及草地生产力。     

Temperate forest responses to carbon dioxide, temperature and nitrogen: a model analysis

The ITE Edinburgh Forest Model, which describes diurnal and seasonal changes in the pools and fluxes of C, N and water in a fully coupled forest–soil system, was parametrized to simulate a managed conifer plantation in upland Britain. The model was used to examine (i) the transient effects on forest growth of an IS92a scenario of increasing [CO₂] and temperature over two future rotations, and (ii) the equilibrium (sustainable) effects of all combinations of increases in [CO₂] from 350 to 550 and 750 μmol mol^?1, mean annual temperature from 7.5 to 8.5 and 9.5°C and annual inputs of 20 or 40 kg N ha^?1. Changes in underlying processes represented in the model were then used to explain the responses. Eight conclusions were supported by the model for this forest type and climate.

• 1 Increasing temperatures above 3°C alone may cause forest decline owing to water stress.
• 2 Elevated [CO₂] can protect trees from water stress that they may otherwise suffer in response to increased temperature.
• 3 In N-limiting conditions, elevated [CO₂] can increase allocation to roots with little increase in leaf area, whereas in N-rich conditions elevated [CO₂] may not increase allocation to roots and generally increases leaf area.
• 4 Elevated [CO₂] can decrease water use by forests in N-limited conditions and increase water use in N-rich conditions.
• 5 Elevated [CO₂] can increase forest productivity even in N-limiting conditions owing to increased N acquisition and use efficiency.
• 6 Rising temperatures (along with rising [CO₂]) may increase or decrease forest productivity depending on the supply of N and changes in water stress.
• 7 Gaseous losses of N from the soil can increase or decrease in response to elevated [CO₂] and temperature.
• 8 Projected increases in [CO₂] and temperature (IS92a) are likely to increase net ecosystem productivity and hence C sequestration in temperate forests.

     

Effects of aerobic training prior to and during chemotherapy in a breast cancer patient: a case study

Treatment for breast cancer patients includes surgical removal of the tumor followed by chemotherapy. Chemotherapy frequently results in difficult to manage symptoms that threaten compliance with the therapy. Symptoms include fatigue, declines in functional ability, muscle wasting, and a decreased quality of life. Preparing the body to tolerate a stressful event such as chemotherapy has been termed "prehabilitation". This case study determined the efficacy of introducing aerobic training 1 week prior to and continuing through 8 weeks of chemotherapy on fatigue and functional ability in a 42-year-old newly diagnosed breast cancer patient. The patient participated in a supervised and home-based walking program. Fatigue during daily activities and functional ability (12-minute walk, ascending and descending stairs, sit to stand, getting to and rising from the floor, 30-second bicep curl) were measured before and after exercise training. Results indicate that 5 of 7 functional measures demonstrated improvement, ranging from 23.4- 54.5%. In addition, fatigue while performing activities of daily living, as well as following the performance of the functional tasks, was reduced. The findings of this case study indicate that fatigue can be decreased and functional ability can be improved as a result of aerobic training initiated 1 week before and continued throughout chemotherapy. This case study presents a novel approach to introducing exercise prior to and continued during 8 weeks of chemotherapy in a way that may reduce the cumulative effects of this stressor.     

Growth and photosynthesis acclimated response of the cyanobacterium Fischerella sp. FS 18 exposed to extreme conditions: alkaline pH,limited irradiance,and carbon dioxide concentration

Extremophiles - The true-branching heterocystous cyanobacterium Fischerella sp. FS 18 is widely distributed in paddy fields (North) and petroleum polluted soils (South) in Iran. This investigation...     

Response of microbial community structure to the hydrochemical evolution during riverbank filtration: a case study in Shenyang,China

Abstract

Microorganisms are widely involved in the transformation process of physical and chemical properties in the geological and hydrogeological environment. Active participation of microorganisms is important features of the biogeochemical reactions during groundwater exploiting along the riverbank filtration. Hydrodynamic condition has a direct or indirect difference control of the biological effectiveness, chemical activity and mobility of the pollution components, which can affect biogeochemical process. In different biogeochemistry, there will be some exclusive functional bacteria, which is of great significance to understand the biogeochemical mechanism of river water infiltration. This study confirms that there are two main different flow paths from river to the center of the depression cone due to different hydrodynamic conditions and spatial characteristics and scaling effects of redox zonation during riverbank filtration. In different flow paths, the microbial abundance shows obvious spatial heterogeneity. The microbial abundance and species similarity degree of the riverbed and deep flow path sediments has significant correlation. There is a significant correlation between the dominant bacteria and the environmental factors in different hydrodynamic conditions on a spatial scale. This study is the first to reveal the response of microbial community structure to water chemical evolution during riparian filtration. Due to significant positive correlation between the Fe/Mn and As, it brings the potential danger for drinking water.     

食物源CNP的城市代谢特征——以厦门市为例

基于元素流分析原理,将食物源碳氮磷3种元素在城市系统中的代谢特征进行耦合分析,追踪以"食物消费"、"废物处置"、"人体代谢"为主要环节的食物碳氮磷代谢过程,发掘其中共同的代谢环节,明晰3种元素代谢路径、代谢通量及其影响因素的差异,并对厦门市1991—2010年食物源碳氮磷城市代谢进行案例分析。结果表明,食物源碳氮磷城市代谢中通量最大的代谢路径是"食物—食物摄入—人体粪尿—未还田粪尿—污水处理—污泥—污泥填埋—土壤";食物源碳氮磷城市代谢主要引起土壤和水体的环境负荷加重;厨余垃圾中碳氮磷占食物源的比例分别为13.7%、32.2%、70.3%,在整个代谢过程中具有最大的减量管理潜力。提出优化代谢过程、减少碳氮磷环境负荷的若干对策建议,包括增大食物的有效食用比例、资源化利用污泥和厨余垃圾等。     

Oxygen supply in disposable shake-flasks: prediction of oxygen transfer rate, oxygen saturation and maximum cell concentration during aerobic growth

Dissolved oxygen plays an essential role in aerobic cultivation especially due to its low solubility. Under unfavorable conditions of mixing and vessel geometry it can become limiting. This, however, is difficult to predict and thus the right choice for an optimal experimental set-up is challenging. To overcome this, we developed a method which allows a robust prediction of the dissolved oxygen concentration during aerobic growth. This integrates newly established mathematical correlations for the determination of the volumetric gas–liquid mass transfer coefficient (k_La) in disposable shake-flasks from the filling volume, the vessel size and the agitation speed. Tested for the industrial production organism Corynebacterium glutamicum, this enabled a reliable design of culture conditions and allowed to predict the maximum possible cell concentration without oxygen limitation.     

Oxygen consumption, carbon dioxide production and progestagen secretion in the intact ovary of the day-16 pregnant rat

Arterial and venous blood gases were measured in the ovary of the Day-16-pregnant rat by a Van Slyke manometric technique. Concurrent observations of progestagen concentrations were also made to determine rates of hormone secretion. The oxygen consumption was 196.5 +/- 28.4 ml/min per kg ovarian tissue (mean +/- s.e.m., n = 8) which is amongst the highest recorded from any organ. Carbon dioxide production was 149.8 +/- 36.6 ml/min per kg ovarian tissue (n = 5) and the respiratory quotient was 0.756 +/- 0.023 (n = 5), indicating that lipids are the major energy substrate used by the ovary. The rates of progestagen secretion were 2.12 +/- 0.37 and 0.42 +/- 0.10 nmol/min per ovary for progesterone and 20 alpha-dihydroprogesterone, respectively, and were not related to oxygen consumption. Less than 1.5% of the oxygen consumed was used in the essential conversion of cholesterol to pregnenolone, the immediate precursor of progesterone.