Aerobic and anaerobic energy during a 2-km race simulation in female rowers

The maximal aerobic power (VO2max) and maximal anaerobic capacity (AODmax) of 16 female rowers were compared to their peak aerobic power (VO2peak) and peak anaerobic capacity (AODpeak, respectively) during a simulated 2-km race on a rowing ergometer. Each subject completed three tests, which included a 2-min maximal effort bout to determine the AODmax, a series of four, 4-min submaximal stages with subsequent progression to VO2max and a simulated 2-km race. Aerobic power was determined using an open-circuit system, and the accumulated oxygen deficit method was used to calculate anaerobic capacities from recorded mechanical power on a rowing ergometer. The average VO2peak (3.58 l min(-1)), which usually occurred during the last minute of the race simulation, was not significantly different (P > 0.05) from the VO2max (3.55 l min(-1)). In addition, the rowers' AODmax (3.40 l) was not significantly different (P > 0.05) from their AODpeak (3.50 1). The average time taken for the rowers to complete the 2-km race simulation was 7.5 min, and the anaerobic system (AODpeak) accounted for 12% of the rowers' total energy production during the race.     

Effect of end-point cadence on the maximal work-time relationship

This study examined the effect of end-point cadence on the parameters of the work-time relationship determined for cycle ergometry. Eight male subjects completed four maximal tests on an electrically-braked cycle ergometer that regulated a constant power output independent of cadence. The power outputs imposed ranged between an average of 259 W and 403 W, whereas the corresponding durations ranged between 139 s and 1691 s. During each test subjects were required to maintain a cadence of 80–90 rpm. Accumulated time to end-point cadences of 70, 60 and 50 rpm were recorded. The four work-time determinations for each of three end-point cadences were used to determine linear relationships between work and time, yielding both a y-intercept, which represents anaerobic work capacity, and a slope, which is termed critical power (CP), for each end-point cadence. There was a significant increase in the y-intercept as end-point cadence decreased from 70 to 60 rpm (F[1,7]=36.7, p < 0.001) or 70 to 50 rpm (F[1,7]=80.1, p < 0.001), but not from 60 rpm to 50 rpm (F[1,7]=3.28, p > 0.05). In contrast, there was no effect of end-point cadence on CP (F[2,14]=1.89, p < 0.05). These results demonstrate that the end-point cadence selected to terminate tests only affects the y-intercept of the work-time relationship. To control for this effect, the cadence at which each test is terminated should be standardised if determination of anaerobic work capacity, as represented by the y-intercept, is required.     

Influence of training status on maximal accumulated oxygen deficit during all-out cycle exercise

The influence of training status on the maximal accumulated oxygen deficit (MAOD) was used to assess the validity of the MAOD method during supramaximal all-out cycle exercise. Sprint trained (ST; n = 6), endurance trained (ET; n = 8), and active untrained controls (UT; n = 8) completed a 90 s all-out variable resistance test on a modified Monark cycle ergometer. Pretests included the determination of peak oxygen uptake ( O_2peak) and a series (5–8) of 5-min discontinuous rides at submaximal exercise intensities. The regression of steady-state oxygen uptake on power output to establish individual efficiency relationships was extrapolated to determine the theoretical oxygen cost of the supramaximal power output achieved in the 90 s all-out test. Total work output in 90 s was significantly greater in the trained groups (P<0.05), although no differences existed between ET and ST. Anaerobic capacity, as assessed by MAOD, was larger in ST compared to ET and UT. While the relative contributions of the aerobic and anaerobic energy systems were not significantly different among the groups, ET were able to achieve significantly more aerobic work than the other two groups, while ST were able to achieve significantly more anaerobic work. Peak power and peak pedalling rate were significantly higher in ST. The results suggested that MAOD determined during all-out exercise was sensitive to training status and provided a useful assessment of anaerobic capacity. In our study sprint training, compared with endurance training, appeared to enhance significantly power output and high intensity performance over brief periods (up to 60 s), yet few overall differences in performance (i.e. total work) existed during 90 s of all-out exercise.     

Oxygen deficits incurred during 45, 60, 75 and 90-s maximal cycling on an air-braked ergometer

The aims of this study were to determine the most appropriate duration for the measurement of the maximal accumulated O₂ deficit (MAOD), which is analogous to the anaerobic capacity, to ascertain the effects of mass, fat free mass (FFM), leg volume (V _leg) and lower body volume (V _1b) on anaerobic test performance, to examine the reproducibility for peak power output ( ) or maximal anaerobic power using an air-braked cycle ergometer and to produce approximations for the percentages of aerobic and anaerobic metabolism during exercise of short duration but high intensity. A group of 12 endurance trained cyclists [mean age 25.1 (SD 4.6) years; mean body mass 73.43 (SD 7.12) kg; mean maximal oxygen consumption 5.12 (SD 0.35) l·min^–1; mean body fat 12.5 (SD 4.1) %] accordingly performed four counterbalanced treatments of 45, 60, 75 and 90 s of maximal cycling on an air-braked ergometer. The mean O₂ deficit of 3.52 l for the 45-s treatment was significantly less (P < 0.01) than those for the 60 (3.75 l), 75 (3.80 l) and 90-s (3.75 l) treatments. These data therefore indicate that in predominantly aerobically trained subjects the O₂ deficit attains a plateau after 60 s of maximal cycling on an air-braked ergometer. Statistically significant interclass correlation coefficients (P<0.05) between the anthropometric variables (mass, FFM, V _leg and V_1b) and or maximal anaerobic power (0.624–0.748) and MAOD (ml) or anaerobic capacity (0.666–0.772) furthermore would suggest the relevance of taking into account muscle mass during anaerobic tests. Intraclass correlation coefficients (0.935–0.946; all P<0.001) would indicate a high degree of reliability for the measurement of . The relative importance of anaerobic work decreased from 60% for the 45-s test to 40% for the 90-s one. Hence our study showed that both aerobic and anaerobic metabolism contributed significantly during all-out tests of 45–90 s duration.     

Anaerobic protozoa and their growth in biomethanation systems

This study was to investigate growth of protozoa and its influence on biodegradation in anaerobic treatment systems. It was done by specifically controlling and monitoring growth of protozoa versus degradation in continuous stirred anaerobic reactors and batch anaerobic reactors. Occurrence of a diverse protozoa population such as the ciliates, Prorodon, Vorticella, Cyclidium, Spathidium, Loxodes, Metopus were observed in stable anaerobic systems and the flagellates, Rhynchomonas, Naeglaria, Amoeboflagellates, Tetramitus, Trepomonas and Bodo during increased VFA concentration and affected periods of biomethanation. The abundance of ciliates in the anaerobic system had significant correlation with the reduction of MLSS, increased rate of COD removal and higher methane production. The results of this study thus tend to relate increased anaerobic degradation with the abundance of protozoa, mainly ciliates, which indicate their possible involvement in the process. Present study also reveals that performance of anaerobic process can be assessed by monitoring the protozoa population in the system.     

Effect of polycyclic aromatic hydrocarbons on the pallial fluid buffering capacity of the marine mussel,Mytilus galloprovincialis

Pallial fluid buffering capacity of the sea mussel Mytilus galloprovincialis was investigated to establish the potential of this biological parameter to serve as a biomarker. Four groups of 15 animals were used in a 72-h toxicity test. Group 1, the aerobic control group, was placed in a filtered aerated natural seawater aquarium. Groups 2-4 were subjected to hypoxic conditions by removal from water after animals were injected with a single dose of the following: group 2 (anaerobic control) was administered 10 microl of UV-treated filtered natural seawater; group 3 (anaerobic solvent control) was injected with 10 microl of acetonitrile and group 4 (PAH exposed group) with 10 microl of 2 mM anthracene. Pallial fluid was taken from all the animals following seawater immersion or air exposure. Pallial fluid from each individual was extracted, adjusted to pH 5.0 and titrated with NaOH until reaching pH 6.0. The buffering capacity index (beta), defined as the amount of mu equivalents of NaOH needed to change in one unit the pH of a 5-ml sample of pallial fluid, was calculated for each group. Values were: for group 1, beta = 3.17 (+/- 0.782); for group 2, beta=15.713 (+/-2.992); group 3 was beta=18.124 (+/-2.288); and group 4 was beta=28.109 (+/-11.398). The statistically significant increase (P<0.05) in group 4 compared with the other groups indicates that the buffering capacity index (beta) is a worthy biological parameter to be further explored as a biomarker for ecotoxicological monitoring programs. The increase in buffering capacity is discussed and a biochemical link between anaerobic metabolism and the exposure to PAH is suggested to explain changes of this biological parameter.     

Can Hypoxia Tolerance Explain Differences in Distribution of Two Co-Occurring North Temperate Sunfishes?

Many small, isolated north temperate waterbodies experience hypoxic conditions and winterkill events. Although such waterbodies are found in the natural ranges of two congeneric sunfishes (pumpkinseed, Lepomis gibbosus and bluegill, L. macrochirus), many contain pumpkinseed but no bluegill; a biogeographic pattern that has remained unexplained. To test whether a greater hypoxia tolerance in pumpkinseeds could explain these differences in distribution, we conducted hypoxia tolerance trials by subjecting each species to declining oxygen concentrations over ca. 16 h in aquaria. We also measured the activities of key metabolic enzymes in the muscle of wild individuals. Pumpkinseeds showed significantly higher tolerance to hypoxic stress than bluegills, as indicated by dissolved oxygen concentration at the time of equilibrium loss. Consistent with this result, white muscle from pumpkinseed had higher levels of lactate dehydrogenase, a marker enzyme for anaerobic capacity. There was no difference between species in the activity level of pyruvate kinase, suggesting that pumpkinseed do not display a general upregulation of glycolysis, but rather an upregulation of anaerobic capacity. Our results support the hypothesis that evolved differences in winter hypoxia tolerance can act as a macrohabitat partitioning mechanism in North American sunfishes.     

厌氧反应器中颗粒污泥的培育及应用研究进展*

厌氧生物处理技术因其具有有机负荷高、污泥产量低、能耗低等优点被广泛应用于各种废水处理中。厌氧颗粒污泥具有沉降性能好、微生物浓度高、有机负荷高等优点,极大地提高了废水处理效率。尤其在处理含高氨氮废水中,厌氧颗粒污泥的形成对反应器的高效生物脱氮至关重要。但到目前为止,厌氧反应器中的颗粒污泥形成及废水处理效果还缺乏系统的认识。鉴于此,总结了厌氧反应器中颗粒污泥的形成机制,分析了影响厌氧反应器中颗粒污泥形成的因素,论述了厌氧反应器中厌氧颗粒污泥生长的模拟,最后介绍了厌氧颗粒污泥在国内外的主流应用。厌氧反应器中颗粒污泥的形成是综合因素影响的结果,对影响厌氧颗粒污泥形成的每个因素都需要认真对待,可为在厌氧反应器中颗粒污泥的培育和应用提供理论指导和技术支撑。     

Microbial Community Dynamics of a Continuous Mesophilic Anaerobic Biogas Digester Fed with Sugar Beet Silage

The aim of the study was to investigate the long‐term fermentation of an extremely sour substrate without any addition of manure. In the future, the limitation of manure and therefore the anaerobic digestion of silage with a very low buffering capacity will be an increasing general bottleneck for energy production from renewable biomass. During the mesophilic anaerobic digestion of sugar beet silage (without top and leaves) as the sole substrate (without any addition of manure), which had an extreme low pH of around 3.3, the highest specific gas production rate (spec. GPR) of 0.72 L/g volatile solids (VS) d was achieved at a hydraulic retention time (HRT) of 25 days compared to an organic loading rate (OLR) of 3.97 g VS/L d at a pH of around 6.80. The methane (CH₄) content of the digester ranged between 58 and 67 %, with an average of 63 %. The use of a new charge of substrate (a new harvest of the same substrate) with higher phosphate content improved the performance of the biogas digester significantly. The change of the substrate charge also seemed to affect the methanogenic population dynamics positively, thus improving the reactor performance. Using a new substrate charge, a further decrease in the HRT from 25 to 15 days did not influence the digester performance and did not seem to affect the structure of the methanogenic population significantly. However, a decrease in the HRT affected the size of the methanogenic population adversely. The lower spec. GPR of 0.54 L/g VS d attained on day 15 of the HRT could be attributed to a lower size of methanogenic population present in the anaerobic digester during this stage of the process. Furthermore, since sugar beet silage is a relatively poor substrate, in terms of the buffering capacity and the availability of nutrients, an external supply of buffering agents and nutrients is a prerequisite for a safe and stable digester operation.     

金属还原菌希瓦氏菌厌氧呼吸能力及其在环境修复中的研究进展

Shewanella oneidensis MR-1是一种模式金属还原菌,它能够在厌氧条件下,将多种金属化合物和人工合成染料等作为电子受体还原代谢。因此,该菌常常被用于生态修复等研究。厌氧条件下,S.oneidensis MR-1能够将细胞质内或细胞内膜产生的电子通过定位于细胞内膜、细胞膜周质和细胞外膜上的c-血红色素蛋白或还原酶所组成的具有多样性的电子传递系统,最终传递到存在于细菌细胞外环境中的电子受体。通过对多种电子传递过程的介绍,进一步阐明其对污染物修复和纳米材料合成的机理,从而为未来对该类微生物的利用和开发提供更为充分的理论依据。     

An alternative method to determine maximal accumulated O2 deficit in runners

An accepted measure of anaerobic capacity is the maximal O2 deficit. But it is not feasible to use O2 deficit if > or =10 submaximal runs are needed to extrapolate the O2 demand of high velocity running (Medb? et al. 1988). Recently, an alternative method to determine O2 deficit was proposed (Hill 1996) using only results of supramaximal cycle ergometer tests. The purpose of this study was to evaluate this alternative method with data from treadmill tests. Twenty-six runners ran at 95%, 100%, 105%, and 110% of their velocity at VO2max. Times to exhaustion, velocity, and accumulated oxygen uptake (VO2) from each individual's four tests were fit to the following equation using iterative nonlinear regression: accumulated VO2 = (O2 demand x velocity x time)-O2 deficit. The mean value s derived for O2 demand and O2 deficit were 0.198+/-0.031 ml x kg(-1) x m(-1) and 42+/-22 ml x kg(-1). SEE for the parameters were 0.007+/-0.007 ml x kg(-1) x m(-1) and 8+/-10 ml x kg(-1), respectively. Mean R2 was 0.998+/-0.003. It was concluded that O2 deficit can be determined from all-out treadmill tests without the need to perform submaximal tests.     

中高温污泥厌氧消化系统中微生物群落比较

【目的】结合中温与高温消化两者优势的两相厌氧消化工艺可能是推进污泥厌氧消化发展的重要方向,因此,探究和比较中温和高温污泥厌氧消化系统中微生物群落组成的异同具有重要意义。【方法】利用高通量测序技术检测中温和高温厌氧消化系统中细菌与古菌的16S r RNA基因序列信息和真菌的内转录间隔(ITS)序列信息,利用基因芯片(Geo Chip 5.0)检测病毒和病原菌致病基因的信息,以对比中温和高温条件下微生物群落在物种组成和功能基因层面上的异同。【结果】中温和高温条件下细菌和古菌在群落物种组成上存在显著差异,病毒和病原菌毒性基因也显著不同,而两种系统中真菌群落的物种组成相似且丰度相对较低。中温条件下产甲烷古菌和未分类微生物相对丰度较高,而高温条件下产酸及嗜热菌相对丰度较高,且高温消化后病毒和病原菌毒性基因相对丰度下降。微生物群落结构与COD、TS和VS有着显著相关性。【结论】微生物群落组成和功能基因在中高温的污泥厌氧消化系统中显著不同,从而解释了两个系统功能的差异。微生物群落的形成与进水参数相关,说明微生物对进水条件敏感。     

Muscle metabolic profile and oxygen transport capacity as determinants of aerobic and anaerobic thresholds

Aerobic and anaerobic thresholds determined by different methods in repeated exercise tests were correlated with cardiorespiratory variables and variables of muscle metabolic profile in 33 men aged 20-50 years. Aerobic threshold was determined from blood lactate, ventilation, and respiratory gas exchange by two methods (AerT1 and AerT2) and anaerobic threshold from venous lactate (AnTLa), from ventilation and gas exchange (AnTr) and by using the criterion of 4 mmol.1(-1) of venous lactate (AnT4mmol). In addition to ordinary correlative analyses, applications of LISREL models were used. The 8 explanatory variables chosen for the regression analyses were height, relative heart volume, relative diffusing capacity of the lung, muscle fiber composition, citrate synthase (CS) and succinate dehydrogenase activities, the lactate dehydrogenase--CS ratio, and age. They explained 58% of the variation in AerT1, 73.5% that of AerT2, 71% that of AnTr, 74.5% that of AnTLa, and 67.5% that of AnT4mmol.AerT and AnT alone explained 77% of the variation in each other. Both AerT and AnT were determined mainly by a muscle metabolic profile, with the CS activity of vastus lateralis as the strongest determinant. The factor 'submaximal endurance' which was measured with AerT and AnT seemed to be slightly more closely connected to 'muscle metabolic profile' than was 'maximal aerobic power' (= VO2max), but both also correlated strongly with each other (r = 0.92).     

ANAMMOX process start up and stabilization with an anaerobic seed in Anaerobic Membrane Bioreactor (AnMBR)

ANaerobic AMMonium OXidation (ANAMMOX) process, an advanced biological nitrogen removal alternative to traditional nitrification--denitrification removes ammonia using nitrite as the electron acceptor without oxygen. The feasibility of enriching anammox bacteria from anaerobic seed culture to start up an Anaerobic Membrane Bioreactor (AnMBR) for N-removal is reported in this paper. The Anammox activity was established in the AnMBR with anaerobic digester seed culture from a Sewage Treatment Plant in batch mode with recirculation followed by semi continuous process and continuous modes of operation. The AnMBR performance under varying Nitrogen Loading Rates (NLR) and HRTs is reported for a year, in terms of nitrogen transformations to ammoniacal nitrogen, nitrite and nitrate along with hydrazine and hydroxylamine. Interestingly ANAMMOX process was evident from simultaneous Amm-N and nitrite reduction, consistent nitrate production, hydrazine and hydroxylamine presence, notable organic load reduction and bicarbonate consumption.     

Anaerobic granulation technology for wastewater treatment

Anaerobic wastewater treatment using granular sludge reactors is a developing technology, in which granular sludge is the core component. So far, around 900 anaerobic granular sludge units have been operated worldwide. Although intensive research attention has been given to anaerobic granules in the past 20 years, the mechanisms responsible for anaerobic granulation and the strategy of how to expedite substantially the formation of granular sludge have not yet been completely clear. This paper reviews the mode of anaerobic granulation, including the mechanisms and models for anaerobic granulation, major factors influencing anaerobic granulation, characteristics of anaerobic granules, anaerobic granulation in other types of reactors, industrial application of anaerobic granulation technology and neural fuzzy model-based control strategy developed for anaerobic systems. Some approaches for future research are outlined.     

Influence of support material properties on the potential selection of Archaea during initial adhesion of a methanogenic consortium

In anaerobic wastewater treatment systems, the complex microbial biomass including Archaea and Bacteria can be retained as a biofilm attached to solid supports. The aim of this study was to evaluate the impact of specific properties of support material on early microbial adhesion. Seven different substrata are described in terms of topography and surface energy. Adhesion of a methanogenic consortium to these substrata was tested, the adhesion was quantified as a percentage of the surface area covered and the bacterial and archaeal community structures was assessed by molecular fingerprinting profiles (CE-SSCP). As expected, the overall adhesion on the supports was influenced mainly by total surface energy. Moreover, the adhered communities were different from the parent inocula, including the Archaea/Bacteria ratio. This could have a significant impact on the start-up of anaerobic digesters for which supports favoring Archaea adhesion, responsible for the limiting reaction of the process, should be preferred.     

Anaerobic digestion of microalgal biomass with ultrasonic disintegration

The use of photosynthetic microalgae for nutrient removal and biofuel production has been widely discussed. Anaerobic digestion of waste microalgal biomass to produce biogas is a promising technology for bioenergy production. However, the methane yield from this anaerobic process was limited because of the hard cell wall of Chlorella vulgaris. The use of ultrasound has proven to be successful at improving the disintegration and anaerobic biodegradability of Chlorella vulgaris. Ultrasonic pretreatment in the range of 5–200 J ml⁻¹ was applied to waste microalgal biomass, which was then used for batch digestion. Ultrasound techniques were successful and showed higher soluble COD at higher applied energy. During batch digestion, cell disintegration due to ultrasound increased in terms of specific biogas production and the degradation rate. Compared to the untreated sample, the specific biogas production was increased in the ultrasound-treated sample by 90% at an energy dose of 200 J ml⁻¹. For the disintegrated samples, volatile solids reduction was also increased according to the energy input and degradation. These results indicate that the hydrolysis of microalgal cells is the rate-limiting step in the anaerobic digestion of microalgal biomass.     

厌氧培养皿及厌氧培养管的临床应用——对传统的厌氧菌分离培养及鉴定方法的简化

利用我们研制的厌氧培养皿及管,共检验了39份牙髓炎及牙周炎标本,分离出厌氧菌59株,标本中厌氧菌分离的阳性率为100％。其中类杆菌28株,消化链球菌9株,消化球菌7株,韦荣氏球菌5株,真杆菌2株,梭形杆菌8株。在类杆菌中产黑素类杆菌21株,占类杆菌总数的75％。结果表明使用厌氧培养皿及管研究厌氧菌简便、有效、经济,适于基层单位应用。     

厌氧消化污泥微生物组研究方法及应用

污泥厌氧消化是在消化污泥微生物组的协调下将剩余污泥中有机物转化为甲烷的微生物过程。与传统厌氧消化过程不同,污泥厌氧消化系统的进料底物为含有大量微生物细胞及胞外多聚物等复杂大分子有机物的剩余污泥。因此,厌氧消化污泥微生物组的种群组成、功能及种群间互作关系等异常复杂,使厌氧消化污泥微生物组分析成为难点问题。但近年来高通量测序技术及生物信息学分析方法的快速发展为消化污泥微生物组研究提供了契机,并迅速推动了该研究领域的发展。本文从4个方面梳理、总结厌氧消化污泥微生物组的研究及应用现状:剩余活性污泥结构、组成及其厌氧消化;基于16SrRNA基因序列测序的微生物组研究;基于宏基因组及宏转录组分析的微生物组研究;厌氧消化污泥微生物组研究案例分析。最后我们提出了厌氧消化污泥微生物组研究亟待解决的关键科学问题。     

Modeling and Analysis of the Effect of Training on \dot{V}O_{2} Kinetics and Anaerobic Capacity

In this paper, we present an application of a number of tools and concepts for modeling and analyzing raw, unaveraged, and unedited breath-by-breath oxygen uptake data. A method for calculating anaerobic capacity is used together with a model, in the form of a set of coupled nonlinear ordinary differential equations to make predictions of the kinetics, the time to achieve a percentage of a certain constant oxygen demand, and the time limit to exhaustion at intensities other than those in which we have data. Speeded oxygen kinetics and increased time limit to exhaustion are also investigated using the eigenvalues of the fixed points of our model. We also use a way of analyzing the oxygen uptake kinetics using a plot of vs which allows one to observe both the fixed point solutions and also the presence of speeded oxygen kinetics following training. A method of plotting the eigenvalue versus oxygen demand is also used which allows one to observe where the maximum amplitude of the so-called slow component will be and also how training has changed the oxygen uptake kinetics by changing the strength of the attracting fixed point for a particular demand.