The effect of dissolved carbon dioxide on penicillin production: Mycelial morphology

The effect of carbon dioxide on the morphology of Penicillium chrysogenum was examined. The scanning electron microscopic (SEM) study indicated that the morphology of P. chrysogenum was subject to change when exposed to various dissolved CO₂ concentrations in the medium. At low influent carbon dioxide partial pressures between 0% and 8%, the predominant morphological form of P. chrysogenum was filamentous. At higher influent carbon dioxide partial pressures of 15% and 20%, the appearance of swollen and stunted hyphae predominated, and a significant quantity of spherical or yeast-like cells were observed. It was evident that for production subject to high dissolved CO₂ concentrations the inhibition of cell growth and penicillin production related strongly to the concomitant morphological changes of P. chrysogenum.     

The effect of high levels of carbon dioxide on dark respiration and growth of plants

Abstract Raising ambient levels of CO₂ during the night, between 350 and 950cm³m^?3, reduced the dark respiration rate of Medicago sativum seedlings. The percentage effect was greater for maintenance respiration than for dark respiration as a whole, and when the plants were in a low photosynthate status. Twenty-four h carbon balance studies confirmed a reduction in night time respiration and an increase of net carbon gain when night time [CO₂] was high. Growth experiments showed a small but significant increase of dry weight in Medicago sativum seedlings exposed to high [CO₂] (～ 1200 cm³m^?3) at night. This effect was greater for plants grown with Rhizobium nodules than for plants grown with nitrate in the absence of Rhizobium. A similar, but smaller and statistically non-significant effect of high night time [CO₂] on growth was found for Xanthium strumarium seedlings. The significance of these findings is discussed in relation to the rising CO₂ content of the atmosphere.     

Root production and mortality under elevated atmospheric carbon dioxide

An essential component of an understanding of carbon flux is the quantification of movement through the root carbon pool. Although estimates have been made using radiocarbon, the use of minirhizotrons provides a direct measurement of rates of root birth and death. We have measured root demographic parameters under a semi-natural grassland and for wheat. The grassland was studied along a natural altitudinal gradient in northern England, and similar turf from the site was grown in elevated CO₂ in solardomes. Root biomass was enhanced under elevated CO₂. Root birth and death rates were both increased to a similar extent in elevated CO₂, so that the throughput of carbon was greater than in ambient CO₂, but root half-lives were shorter under elevated CO₂ only under a Juncus/Nardus sward on a peaty gley soil, and not under a Festuca turf on a brown earth soil. In a separate experiment, wheat also responded to elevated CO₂ by increased root production, and there was a marked shift towards surface rooting: root development at a depth of 80–85 cm was both reduced and delayed. In conjunction with published results for trees, these data suggest that the impact of elevated CO₂ will be system-dependent, affecting the spatio-temporal pattern of root growth in some ecosystems and the rate of turnover in others. Turrnover is also sensitive to temperature, soil fertility and other environmental variables, all of which are likely to change in tandem with atmospheric CO₂ concentrations. Differences in turnover and time and location of rhizodeposition may have a large effect on rates of carbon cycling.     

The effect of elevated atmospheric carbon dioxide levels on soil bacterial communities

The effect of elevated carbon dioxide levels on total bacterial communities was studied in a series of controlled and replicated model terrestrial ecosystems over a period of 38 weeks. The bacterial community was profiled using Denaturing Gradient Gel Electrophoresis (DGGE) analysis of bacterial 16S rRNA gene fragments amplified by the Polymerase Chain Reaction from DNA extracted directly from soil. Bacterial community DGGE profiles provided three major findings: (i) there was a high degree of profile similarity after ≈ 12 weeks (one plant generation); (ii) whilst overall DGGE profile was maintained over the 38 weeks (three plant generations), the banding patterns became more diverse with time; (iii) DGGE data provided no evidence for a shift in bacterial community structure resulting from exposure of the ecosystem to an increased atmospheric CO₂ level.     

The role of carbon dioxide in light-activated hydrogen production by Chlamydomonas reinhardtii

Light-activated hydrogen and oxygen evolution as a function of CO₂ concentration in helium were measured for the unicellular green alga Chlamydomonas reinhardtii. The concentrations were 58, 30, 0.8 and 0 ppm CO₂. The objective of these experiments was to study the differential affinity of CO₂/HCO₃^- for their respective Photosystem II and Calvin cycle binding sites vis-à-vis photoevolution of molecular oxygen and the competitive pathways of hydrogen photoevolution and CO₂ photoassimilation. The maximum rate of hydrogen evolution occurred at 0.8 ppm CO₂, whereas the maximum rate of oxygen evolution occurred at 58 ppm CO₂. The key result of this work is that the rate of photosynthetic hydrogen evolution can be increased by, at least partially, satisfying the Photosystem II CO₂/HCO₃^- binding site requirement without fully activating the Calvin-Benson CO₂ reduction pathway. Data are presented which plot the rates of hydrogen and oxygen evolution as functions of atmospheric CO₂ concentration in helium and light intensity. The stoichiometric ratio of hydrogen to oxygen changed from 0.1 at 58 ppm to approximately 2.5 at 0.8 ppm. A discussion of partitioning of photosynthetic reductant between the hydrogen/hydrogenase and Calvin-Benson cycle pathways is presented.Abbreviations PET photosynthetic electron transport - PS Photosystem     

The effect of carbon dioxide concentration on respiration of growing and mature soybean leaves

Soybean plants were grown continuously at 350 and 700cm³m^?3 CO₂ at constant temperature. Respiration rates of third trifoliolate leaves were measured at the growth CO₂ concentration for the whole dark period from 5d before through to 5d after full area expansion. The short-term response of respiration rate to the measurement CO₂ concentration was also determined at each age. Respiration rates per unit of dry mass declined with age and were significantly less at a given age or RGR in leaves grown and measured at the elevated CO₂. The difference in respiration rate was largest in mature leaves and resulted from the different measurement CO₂ concentrations. The respiratory costs of the tissue synthesis, estimated from the elemental composition of the tissue, did not differ substantially between CO₂ treatments. The response of respiration rate to carbon dioxide concentration was not strongly affected by the form of nitrogen supplied. Maintenance respiration calculated by subtracting growth respiration from total respiration was negative in rapidly growing leaves for both CO₂ treatments. This indicates that CO₂ efflux in the dark does not accurately reflect the average 24 h rate of energy expenditure on growth and maintenance for soybean leaves.     

Effect of carbon dioxide concentration on the bioleaching of a pyrite-arsenopyrite ore concentrate

The effect of carbon dioxide concentration on the bacterial leaching of a pyrite-arsenopyrite ore concentrate was studied in continuous-flow reactors. Steady-state operation with two feed slurry densities, 6 wt% and 16 wt% solids, were tested for the effect of carbon dioxide concentration. Bacterial growth rates were estimated via the measurement of carbon dioxide consumption rates. Aqueous-phase carbon dioxide concentrations in excess of 10 mg/L were found to be inhibitory to bacterial growth. (c) 1993 John Wiley & Sons, Inc.     

土壤有机碳和外源添加碳对水稻土土体呼吸的影响

土体呼吸输出碳来源于土壤固有有机碳和外源添加碳,而以往关于不同施肥措施对水稻土碳排放的研究少有区分碳的来源。本试验利用一个长达30年的水稻土定位试验,在保证原有定位试验继续正常开展的前提下变更部分施肥处理,得到继续施用高量有机肥(HOM)、施用常量有机肥30年后改施高量有机肥(N-H)、继续施用常量有机肥(NOM)、施用化肥30年后改施常量有机肥(C-N)、施用高量有机肥30年后改施化肥(H-C)、施用常量有机肥30年后改施化肥(N-C)、继续施用化肥(CF)等7种施肥处理。通过观测早稻生长期间原有施肥和改施肥处理土体CO2排放通量(FCO2),研究不同后续施肥对水稻土FCO2的影响,以期探讨土壤原始有机碳和外源添加碳对土壤FCO2的影响。结果表明:7种不同施肥处理土体CO2平均排放通量(F珔CO2)分别为85.34、69.10、51.27、49.15、14.89、12.92和11.59 mg C.m-2.h-1;对施用无机肥料和常量有机肥料的土体而言,土壤本身有机碳含量对F珔CO2无显著影响,但对施用高量有机肥的土体而言,土壤本身的高有机碳含量会增强F珔CO2;CO2排放通量(Y)与添加外源碳量(x)之间符合指数方程:Y=13.33e1.719 x(R2=0.967,n=21),施入的外源有机碳对土体FCO2产生极显著影响;当季外源添加碳以CO2-C矿化分解释放的碳占其总碳量的14%左右,且该分解率受土壤有机碳含量和有机物料添加量的影响较小。     

Inactivation of Pseudomonas aeruginosa biofilm by dense phase carbon dioxide

Dense phase carbon dioxide (DPCD) is one of the most promising techniques available to control microorganisms as a non-thermal disinfection method. However, no study on the efficiency of biofilm disinfection using DPCD has been reported. The efficiency of DPCD in inactivating Pseudomonas aeruginosa biofilm, which is known to have high antimicrobial resistance, was thus investigated. P. aeruginosa biofilm, which was not immersed in water but was completely wet, was found to be more effectively inactivated by DPCD treatment, achieving a 6-log reduction within 7 min. The inactivation efficiency increased modestly with increasing pressure and temperature. This study also reports that the water-unimmersed condition is one of the most important operating parameters in achieving efficient biofilm control by DPCD treatment. In addition, observations by confocal laser scanning microscopy revealed that DPCD treatment not only inactivated biofilm cells on the glass coupons but also caused detachment of the biofilm following weakening of its structure as a result of the DPCD treatment; this is an added benefit of DPCD treatment.     

CO2转化酶的固定化研究

CO2是导致温室效应的主要气体,固定和转化CO2的研究对于温室效应的减缓和环境保护方面具有重要意义。近年来CO2转化的研究取得了迅猛发展,其中生物法固定CO2由于其反应条件温和且绿色无污染的优点而备受关注。本文对转化CO2有关的乳酸脱氢酶（LDH）、苹果酸脱氢酶（MDH）和草酰乙酸脱羧酶（OAADC）进行了初步的固定化分析。首先以碳纳米管、壳聚糖和海藻酸钠为原料,制备了包埋上述CO2转化酶的微胶囊固定化体系,然后分别比较了游离酶和固定化酶的操作稳定性和储存稳定性。研究结果表明,固定化的CO2转化酶的操作稳定性和储存稳定得到明显的提高。本研究对CO2的转化和应用方面具有重要参考价值。     

水菖蒲超临界CO_2萃取物对德国小蠊的触杀和驱避活性

水菖蒲(Acorus calamus L.)超临界CO2萃取物对德国小蠊Blattella germanica L.同时具有很好的触杀和驱避活性。采用药膜接触法和滤纸药膜选择法,分别研究水菖蒲超临界CO2萃取物对德国小蠊3龄若虫的触杀和驱避活性。结果表明:水菖蒲超临界CO2萃取物对德国小蠊的生物活性存在着明显的浓度-时间-效应。触杀作用中处理试虫12h后,最高浓度124.00μg/cm2的校正死亡率就达到98.33%,24h后达到100%。试虫在处理12h后的LC50为36.45μg/cm2。驱避活性中,最高浓度815.28μg/cm2的驱避率为67.73%,驱避等级达到了Ⅳ级。     

The effect of transcutaneous application of carbon dioxide (CO2) on skeletal muscle

In Europe, carbon dioxide therapy has been used for cardiac disease and skin problems for a long time. However there have been few reports investigating the effects of carbon dioxide therapy on skeletal muscle. Peroxisome proliferators-activated receptor (PPAR)-gamma coactivator-1 (PGC-1α) is up-regulated as a result of exercise and mediates known responses to exercise, such as mitochondrial biogenesis and muscle fiber-type switching, and neovascularization via up-regulation of vascular endothelial growth factor (VEGF). It is also known that silent mating type information regulation 2 homologs 1 (SIRT1) enhances PGC-1α-mediated muscle fiber-type switching. Previously, we demonstrated transcutaneous application of CO₂ increased blood flow and a partial increase of O₂ pressure in the local tissue known as the Bohr effect. In this study, we transcutaneously applied CO₂ to the lower limbs of rats, and investigated the effect on the fast muscle, tibialis anterior (TA) muscle. The transcutaneous CO₂ application caused: (1) the gene expression of PGC-1α, silent mating type information regulation 2 homologs 1 (SIRT1) and VEGF, and increased the number of mitochondria, as proven by real-time PCR and immunohistochemistry, (2) muscle fiber switching in the TA muscle, as proven by isolation of myosin heavy chain and ATPase staining. Our results suggest the transcutaneous application of CO₂ may have therapeutic potential for muscular strength recovery resulting from disuse atrophy in post-operative patients and the elderly population.     

不同压力二氧化碳气腹对兔血液流变学和微循环的影响

目的：研究不同压力二氧化碳气腹对兔血液流变学和微循环的影响。方法：18只雌性健康实验兔按气腹压力随机均分为三组：气腹压0mmHg组（Ⅰ组）、气腹压10mmHg组（Ⅱ组）和气腹压15mmHg组（Ⅲ组）。每组兔均在不同的压力下接受气腹1h。在二氧化碳气腹前5min（T0）、气腹后30min（T1）、气腹后60min（T2）测定血液流变学指标。监测心率（HR）、平均动脉压（MAP）、耳廓微循环的血流量和血流速率并记录在相应时点的上述参数值。结果：气腹后30min、60min,Ⅱ组与Ⅰ组比较,HR、MAP、全血粘度、红细胞刚性指数和聚集指数显著增加（P〈0.05）,红细胞变形指数、耳廓微循环的血流量和血流速率显著下降（P〈0.05）,Ⅲ组与Ⅰ组比较,各参数变化更为显著（P〈0.01）。血浆粘度和红细胞压积气腹前后无明显变化。结论：二氧化碳气腹后血液流变性减弱;虽然HR、MAP增加,但微循环的血流量和血流速率下降。     

Exploiting the pressure effect on lipase-catalyzed wax ester synthesis in dense carbon dioxide

The present work focuses on the thermodynamic interpretation of the lauryl oleate biosynthesis in high-pressure carbon dioxide. Lipase-catalyzed lauryl oleate production by oleic acid esterification with 1-dodecanol over immobilized lipase from Rhizomucor miehei (Lipozyme RM IM) was successfully performed in a sapphire window batch stirred tank reactor (BSTR) using dense CO(2) as reaction medium. The experiments were planned to elucidate the pressure effect on the reaction performance. With increasing the pressure up to 10 MPa, the catalytic efficiency of the studied enzyme improved rising up to a maximum and decreased at higher pressure values. Kinetic observations, exhibiting that dense CO(2) expanded reaction mixture in subcritical conditions led to higher performance than when diluted in a single supercritical phase, were elucidated by phase-equilibrium arguments. The experimental results were justified with emphasis on thermodynamic interpretation of the studied system. Particularly, the different reaction performances obtained were related to the position of the operating point with respect to the location of liquid-vapor phase boundaries of the reactant fatty acid/alcohol/CO(2) ternary system. The outlook for exploitation of CO(2) expanded phase at lower pressure compared to supercritical phase, with heterogeneous system in which the solid catalyst particles are exposed to dense CO(2) expanded reaction mixture, in developing new biotransformation schemes is promising.     

Effect of carbon dioxide on the Oriental cockroach Blatta orientalis

Exposure to high concentrations of carbon dioxide (CO2) killed adult and nymphal stages of the oriental cockroach Blatta orientalis L. (Dictyoptera: Blattidae) with LT50 values of 11.5-16.2 h for 60% CO2 in air and 5.7-7.1 h for 100% CO2 at 20 degrees C; corresponding LT50s at 28 degrees C were 2.8-4.6 h for 60% CO2 in air and 2.3-3.6 h for 100% CO2. Complete kill of mobile stages was obtained within 24 h using 60% CO2 at 20 degrees C. Survivors of treatments with 100% CO2 at 28 degrees C remained completely paralysed for up to 3 days post-treatment and took up to 5 days to regain normal movement, but adult females then resumed production of oothecae with no significant loss in fecundity. Oothecae 5 or 30 days after deposition required 60-84 h exposure to 60% CO2 at 20 degrees C to prevent emergence of nymphs but less time using 100% CO2 at 28 degrees C. At 28 degrees C, when adult females were treated with 100% CO2 and 52% r.h. for 6 h (giving 100% mortality) loss of weight was significantly greater than that following treatment with air at 52% r.h. for 6 h (giving no mortality). However, significantly greater weight loss also occurred when they were treated with dried air (< 10% r.h.) for 6 h, also with no mortality. The toxicity of CO2 to mobile stages of the oriental cockroach appeared to result from irreversible effects on the nervous system, rather than from water loss during exposure.     

Characterisation of a novel support for biocatalysis in supercritical carbon dioxide

The work presents a characterisation study of Accurel EP100 (polypropylene based hydrophobic granules) as support material for lipase (Lypozyme 10,000 l, from native Rhizomucor miehei) operating as biocatalyst in supercritical CO₂ as solvent. The study involved assay of biocatalytic activity and operational stability as functions of system pressure and temperature. Furthermore, the presence of diffusion limitations was tested, by varying the bed diameter and support particle size. In addition, SEM and Gas Absorption were employed to test the mechanical stability. Results were compared with the commercially available biocatalyst Lipozyme™ IM60.

Pressure did not have a significant effect on the activity or the stability, while temperature had a positive effect on the activity and negative effect on the stability. As expected, an ‘optimum’ value of system water content gave maximum catalytic activity for each biocatalyst. External- and internal-diffusion limitations were both found negligible. The mechanical stability analysis demonstrated little (if any) effect of supercritical carbon dioxide (scCO₂) on the structural integrity of Accurel EP100, although subtle increases in pore volume and surface area were observed.     

Effects of carbon dioxide sequestration on California margin deep-sea foraminiferal assemblages

Deep-sea sequestration of CO₂ is being considered as a possible mitigation tool to decrease atmospheric CO₂ concentrations and its associated negative effects. This study investigated potential effects of liquid carbon dioxide (CO₂) injection on deep-sea foraminiferal assemblages. Foraminifera are ideal for this ecological impact investigation because of differing test composition (calcareous and non-calcareous) and thickness, and diverse epifaunal and infaunal depth preferences. The experiment was conducted on August–September 2003, at 3600 m off the coast of Monterey Bay, California, aboard the R/V Western Flyer using the ROV Tiburon. The pH of the site was monitored throughout the experiment. Sediment push-cores were collected (both from the experimental and control sites) and stained to distinguish live (stained) from dead (unstained) individuals. Effects of CO₂ injection on assemblages have been tracked both vertically (to 10 cm depth below sea floor) and horizontally (up to 10 m from CO₂ injection sites), as well as between live and dead individuals. Within corrals (containing the injected CO₂) and their underlying sediments, severe pH changes (near 4.0 units) were recorded. This compares with a record of small average reductions in ocean pH (− 0.05 units) combined with large episodic excursions (− 1.7 units) over the experimental area due to the injection of CO₂. Exposure to this gradient of low pH caused increased mortality and dissolution of calcareous forms within corrals, as far as 5 m from the injection site, and to at least 10 cm depth in the sediments.This experiment revealed several major effects of CO₂ injection on foraminiferal assemblages in surficial sediments: 1) total number of foraminifera in a sample decreases; 2) foraminiferal species richness decreases in both stained and unstained specimens; and 3) relative percentage of stained (live) forms in the remaining tests increases. Down-core trends (to 10 cm below sea floor) have revealed: 1) percent agglutinated forms decline and calcareous forms increase with depth; 2) agglutinated species richness decreases with depth; and 3) experimental core assemblages become increasingly similar with depth to those in control cores not subjected to CO₂ injection. These results imply almost complete initial mortality and dissolution in the upper 10 cm throughout the corrals following liquid CO₂ injection. Since calcareous foraminifera represent more than 50% of the total assemblages, this clearly indicates that emplacement of CO₂ will result in negative effects to diversity and survivorship of the deep-sea benthic meiofauna.     

卵液成分改变及卵表涂施引诱剂对玉米螟赤眼蜂产卵发育的影响

试验通过部分改变人造卵卵液成分和在人造卵表涂施引诱剂2种途径来试图提高人造卵繁育玉米螟赤眼蜂Trichogramma ostriniae Panget Chen的成功率。结果表明,不同比例的亚洲玉米螟OstriniafurnacalisGuenée幼虫和蛹匀浆替代部分柞蚕蛹匀浆后,对赤眼蜂寄生率有明显提高,但赤眼蜂在人造卵内的化蛹率和羽化率均较低,赤眼蜂发育至老熟幼虫因卵液过剩而被淹死;在原卵液卵表涂施亚洲玉米螟卵和鳞片正己烷提取液后,评价繁蜂成功率的各项参数都有明显提高,赤眼蜂可以完成发育,羽化成蜂,但繁蜂成功率还较低。综合上述试验结果,应用人造卵繁殖玉米螟赤眼蜂研究重点要解决卵液过剩以及其它相关的营养学问题。