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51.
The effect of microbial enzymes in reducing the disposable solid content of sludge was investigated. A mixture of industrial
cellulase, protease, and lipase, in equal proportion by weight, reduced total suspended solids (TSS) by 30–50% and improved
settling of solids. An increase in solid reduction was observed with increasing enzyme concentration. The effect of combinations
of enzyme treatments indicated that two-enzyme combinations of protease and cellulase produced better solid reduction than
individual enzymes and that lipase further augmented this effect. Among the individual enzymes, protease produced a more settleable
sludge as compared to cellulase and lipase. Adjustment of the pH of the enzymatically treated sludge to the acidic range (pH
2–4) further improved solid reduction, and adjustment to the alkaline range (pH 10–12) improved settleability. Journal of Industrial Microbiology & Biotechnology (2001) 26, 383–386.
Received 01 November 2000/ Accepted in revised form 29 April 2001 相似文献
52.
Alfalfa (Medicago sativa L.) growth and nodulation in acid soil is reduced because the plant and its bacterial symbiontRhizobium meliloti cannot tolerate acid, aluminum-rich soil. A study was conducted to determine if a relatively acid-tolerant alfalfa germplasm combined with a relatively acid-tolerantR. meliloti strain could overcome these limitations. In a light room study, an acid-tolerant alfalfa germplasm inoculated with a more acid-tolerantR. meliloti strain produced greater top growth, nodule number and weight, and acetylene reduction values in an unlimed soil (pH 4.6) than the same germplasm inoculated with a relatively acid-sensitiveR. meliloti strain or an acid-sensitive germplasm inoculated with either a relatively acid-tolerant or acid-sensitiveR. meliloti strain. 相似文献
53.
54.
The perchlorate (ClO4−)-respiring organism, strain perc1ace, can grow using nitrate (NO3−) as a terminal electron acceptor. In resting cell suspensions, NO3− grown cells reduced ClO4−, and ClO4− grown cells reduced NO3−. Activity assays showed that nitrate reductase (NR) activity was 1.31 μmol min−1 (mg protein)−1 in ClO4− grown cells, and perchlorate reductase (PR) activity was 4.24 μmol min−1 (mg protein)−1 in NO3− grown cells. PR activity was detected within the periplasmic space, with activities as high as 14 μmol min−1 (mg protein)−1. The NR had a pH optimum of 9.0 while the PR had an optimum of 8.0. This study suggests that separate terminal reductases are present in strain perclace to reduce NO3− and ClO4−. 相似文献
55.
Furtmüller PG Arnhold J Jantschko W Pichler H Obinger C 《Biochemical and biophysical research communications》2003,301(2):551-557
Myeloperoxidase (MPO) is an important component of the neutrophil's antimicrobial armory and has been implicated in promoting tissue damage in numerous inflammatory diseases. For the first time the standard reduction potential of the redox couple compound II/native enzyme has been determined to be (0.97+/-0.01)V at pH 7.0 and 25 degrees C. This was achieved by rapid mixing of preformed compound II with either tyrosine or nitrite by using the sequential-mixing stopped-flow technique and measuring spectrophotometrically the concentrations of the reacting species and products at equilibrium. Using the recently determined standard reduction potential for the couple compound I/native enzyme (1.16 V), the reduction potential of the couple compound I/compound II was calculated to be 1.35 V at pH 7 and 25 degrees C. These data reveal substantial differences between the two known heme peroxidase superfamilies and reflect the dramatic differences observed in the oxidisability of substrates by the MPO redox intermediates compound I and compound II. 相似文献
56.
Alenka Mavri Mojca Stegnar Joica T. Sento
nik Viktor Vide
nik 《Obesity (Silver Spring, Md.)》2001,9(9):511-516
Objective: To investigate the extent of carotid atherosclerosis and the effect of weight loss on carotid intima‐media thickness (IMT) in obese premenopausal women. Research Methods and Procedures: In 43 obese premenopausal women who participated in a 3‐month weight reduction program with a hypocaloric diet, IMT was measured by B‐mode high‐resolution ultrasound at entry and after 5 months of follow‐up. Blood samples were analyzed at entry, after intervention, and after 5 months of follow‐up. Nineteen lean women served as control subjects. Results: At entry, common carotid IMT (0.72 vs. 0.59 mm), carotid bulb IMT (0.90 vs. 0.71 mm), and overall mean IMT (0.81 vs. 0.65 mm) were greater in obese women than in lean women (all p < 0.01). After dietary intervention decreases in blood pressure, low density lipoprotein to high density lipoprotein cholesterol ratio, triglycerides, fibrinogen, plasminogen activator inhibitor‐1, and an increase in tissue‐type plasminogen activator activity levels were observed. These effects persisted after follow‐up in 14 women who maintained reduced weight. Reduction in carotid bulb IMT (to 0.81 mm, p < 0.01) and overall mean IMT (to 0.79 mm, p < 0.05) was observed in this subgroup. No significant change of carotid IMT was detected in eight women who regained weight. Changes in IMT were associated independently and significantly with changes in body mass index, low density lipoprotein to high density lipoprotein cholesterol ratio, and plasminogen activator inhibitor‐1 antigen. Discussion: Obese premenopausal women had greater IMT than did age‐matched lean controls. It seems that this early atherosclerotic changes may be reversed by normalization of body weight. 相似文献
57.
Zn‐Air Batteries: Composites of a Prussian Blue Analogue and Gelatin‐Derived Nitrogen‐Doped Carbon‐Supported Porous Spinel Oxides as Electrocatalysts for a Zn–Air Battery (Adv. Energy Mater. 22/2016) 下载免费PDF全文
58.
LUITGARD SCHWENDENMANN EDZO VELDKAMP GERALD MOSER DIRK HÖLSCHER MICHAEL KÖHLER YANN CLOUGH ISWANDI ANAS GUNAWAN DJAJAKIRANA STEFAN ERASMI DIETRICH HERTEL DANIELA LEITNER CHRISTOPH LEUSCHNER BEATE MICHALZIK PAVEL PROPASTIN AIYEN TJOA TEJA TSCHARNTKE OLIVER Van STRAATEN 《Global Change Biology》2010,16(5):1515-1530
Agroforestry systems may play a critical role in reducing the vulnerability of farmers' livelihood to droughts as tree‐based systems provide several mechanisms that can mitigate the impacts from extreme weather events. Here, we use a replicated throughfall reduction experiment to study the drought response of a cacao/Gliricidia stand over a 13‐month period. Soil water content was successfully reduced down to a soil depth of at least 2.5 m. Contrary to our expectations we measured only relatively small nonsignificant changes in cacao (?11%) and Gliricidia (?12%) sap flux densities, cacao leaf litterfall (+8%), Gliricidia leaf litterfall (?2%), soil carbon dioxide efflux (?14%), and cacao yield (?10%) during roof closure. However, cacao bean yield in roof plots was substantially lower (?45%) compared with control plots during the main harvest following the period when soil water content was lowest. This indicates that cacao bean yield was more sensitive to drought than other ecosystem functions. We found evidence in this agroforest that there is complementary use of soil water resources through vertical partitioning of water uptake between cacao and Gliricidia. This, in combination with acclimation may have helped cacao trees to cope with the induced drought. Cacao agroforests may thus play an important role as a drought‐tolerant land use in those (sub‐) tropical regions where the frequency and severity of droughts is projected to increase. 相似文献
59.
Pimenov N. V. Savvichev A. S. Rusanov I. I. Lein A. Yu. Ivanov M. V. 《Microbiology》2000,69(6):709-720
Functioning of microbial communities in surface sediments of the Haakon Mosby underwater mud volcano (lat. 72°N) and in gas seepage fields of the Vestnesa Ridge was investigated using Mir-1 and Mir-2 deep-sea submersibles during the 40th voyage of the research vessel Academician Mstislav Keldysh. Large areas of sedimentary deposits of the Haakon Mosby mud volcano (HMMV) and pockmarks of the Vestnesa Ridge (VR) are covered with bacterial mats 0.1 to 0.5 cm thick. The microbial community making up bacterial mats of the HMMV was dominated by large filamentous bacteria with filaments measuring up to 100 m in length and 2 to 8 m in width. The occurrence of rosettes allowed the observed filamentous bacteria to be referred to the morphologically similar genera Leucothrix or Thiothrix. Three morphological types of filamentous bacteria were identified in bacterial mats covering VR pockmarks. Filaments of type one are morphologically similar with representatives of the genera Thioploca or Desmanthos. Type two filaments had numerous inclusions of sulfur and resembled representatives of the genus Thiothrix. The third morphological type was constituted by single filaments made up of tightly connected disk-like cells and can be assigned to the genus Beggiatoa. The rates of methane oxidation (up to 1570 l C/(dm3 day)) and sulfate reduction (up to 17 mg S/(dm3day)) measured in the surface sediments of HMMV and VR were close to the maximum rates of these processes observed in heavily polluted regions of the northwestern shelf of the Black Sea. High rates of microbiological processes correlated with the high number of bacteria. The rate of methane production in sediments studied was notably lower and ranged from 0.1 to 3.5 CH4/(dm3 day). Large areas of the HMMV caldera were populated by pogonophoras, represented by the two species Sclerolinum sp. and Oligobrachia sp. The mass development of Sclerolinum sp. in the HMMV caldera was by the activity of aerobic methane-oxidizing bacteria localized inside the cells of these animals. Bacterial cells were also found in the trophosome tissue of Oligobrachia sp., but in cells of these bacteria, we did not observe the membrane structures typical of methanotrophs. The localization pattern of pogonophoras on the surface of reduced sediments suggests that the predominant bacteria in Oligobrachia tissues are sulfur-oxidizing endosymbionts. 相似文献
60.
Stefan Brutigam Danielle Dennewald Melanie Schürmann Jeffrey Lutje-Spelberg William-Robert Pitner Dirk Weuster-Botz 《Enzyme and microbial technology》2009,45(4):310-316
A biphasic process design is often applied in whole-cell biocatalysis if substrate and product have low water solubility, are unstable in water or toxic for the biocatalyst. Some water immiscible ionic liquids (ILs) with adequate distribution coefficients have already been applied successfully as second liquid phase, which acts as a substrate reservoir and in situ extractant for the product. In this work, 12 new ILs were evaluated with respect to their applicability in biphasic asymmetric reductions of prochiral ketones in comparison to 9 already published ILs. The ILs under study are composed of seven different cations and three different anions. Recombinant Escherichia coli was used as whole-cell biocatalyst overexpressing the genes of a Lactobacillus brevis alcohol dehydrogenase (LB-ADH) and a Candida boidinii formate dehydrogenase (CB-FDH) for cofactor regeneration. Best results were achieved if ionic liquids with [PF6]- and [NTF]-anions were applied, whereas [FAP]-ILs showed minor qualification, e.g., the use of [HMPL][NTF] as second liquid phase for asymmetric synthesis of (R)-2-octanol resulted in a space–time-yield of 180 g L−1 d−1, a chemical yield of 95% and an enantiomeric excess of 99.7% in a simple batch process. 相似文献