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Sole Substrate (sole + substrate)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

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

ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2008
B. Demirel
Abstract 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. [source]

NF-,B involvement in the induction of high affinity CAT-2 in lipopolysaccharide-stimulated rat lungs

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2004
C.-J. Huang
Background:, Endotoxemia stimulates nitric oxide (NO) biosynthesis through induction of inducible NO synthase (iNOS). Cellular uptake of l -arginine, the sole substrate for iNOS, is an important mechanism regulating NO biosynthesis by iNOS. The isozymes of type-2 cationic amino acid transporters, including CAT-2, CAT-2A, and CAT-2B, constitute the most important pathways responsible for trans -membrane l -arginine transportation. Therefore, regulation of CAT-2 isozymes expression may constitute one of the downstream regulatory pathways that control iNOS activity. We investigated the time course of enzyme induction and the role of nuclear factor-,B (NF-,B) in CAT-2 isozymes expression in lipopolysaccharide-(LPS) treated rat lungs. Methods:, Adult male Sprague,Dawley rats were randomly given intravenous injections of normal saline (N/S), LPS, LPS plus NF-,B inhibitor pre-treatment (PDTC, dexamethasone, or salicylate), or an NF-,B inhibitor alone. The rats were sacrificed at different times after injection and enzyme expression and lung injury were examined. Pulmonary and systemic NO production were also measured. Results:, LPS co-induced iNOS, CAT-2, and CAT-2B but not CAT-2A expression in the lungs. Furthermore, NF-,B actively participated in LPS-induction of iNOS, CAT-2, and CAT-2B. LPS induced pulmonary and systemic NO overproduction and resulted in lung injuries. Attenuation of LPS-induced iNOS, CAT-2, and CAT-2B induction significantly inhibited NO biosynthesis and lessened lung injury. Conclusion:, NF-,B actively participates in the induction of CAT-2 and CAT-2B in intact animals. Our data further support the idea that CAT-2 and CAT-2B are crucial in regulating iNOS activity. [source]

Purification of bioethanol effluent in an UASB reactor system with simultaneous biogas formation

BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2003
M. Torry-Smith
In this study, the prospect of using an Upflow Anaerobic Sludge Blanket (UASB) reactor for detoxification of process water derived from bioethanol production has been investigated. The bioethanol effluent (BEE) originated from wet oxidized wheat straw fermented by Saccharomyces cerevisiae and Thermoanaerobacter mathranii A3M4 to produce ethanol from glucose and xylose, respectively. In batch experiments the methane potential of BEE was determined to 529 mL-CH4/g-VS. In batch degradation experiments it was shown that the presence of BEE had a positive influence on the removal of the inhibitors 2-furoic acid, 4-hydroxyacetophenone, and acetovanillone as compared to conversion of the inhibitors as sole substrate in synthetic media. Furthermore, experiments were carried out treating BEE in a laboratory-scale UASB reactor. The results showed a Chemical Oxygen Demand (COD) removal of 80% (w/w) at an organic loading rate of 29 g-COD/(L · d). GC analysis of the lignocellulosic related potentially inhibitory compounds 2-furoic acid, vanillic acid, homovanillic acid, acetovanillone, syringic acid, acetosyringone, syringol, 4-hydroxybenzoic acid, and 4-hydroxybenzaldehyde showed that all of these compounds were removed from the BEE in the reactor. Implementation of a UASB purification step was found to be a promising approach to detoxify process water from bioethanol production allowing for recirculation of the process water and reduced production costs. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 7,12, 2003. [source]

Thermophilic (55,65 °C) and Extreme Thermophilic (70,80 °C) Sulfate Reduction in Methanol and Formate-Fed UASB Reactors

BIOTECHNOLOGY PROGRESS, Issue 5 2004
Marcus V. G. Vallero
The feasibility of thermophilic (55,65 °C) and extreme thermophilic (70,80 °C) sulfate-reducing processes was investigated in three lab-scale upflow anaerobic sludge bed (UASB) reactors fed with either methanol or formate as the sole substrates and inoculated with mesophilic granular sludge previously not exposed to high temperatures. Full methanol and formate degradation at temperatures up to, respectively, 70 and 75 °C, were achieved when operating UASB reactors fed with sulfate rich (COD/SO42 - = 0.5) synthetic wastewater. Methane-producing archaea (MPA) outcompeted sulfate-reducing bacteria (SRB) in the formate-fed UASB reactor at all temperatures tested (65,75 °C). In contrast, SRB outcompeted MPA in methanol-fed UASB reactors at temperatures equal to or exceeding 65 °C, whereas strong competition between SRB and MPA was observed in these reactors at 55 °C. A short-term (5 days) temperature increase from 55 to 65 °C was an effective strategy to suppress methanogenesis in methanol-fed sulfidogenic UASB reactors operated at 55 °C. Methanol was found to be a suitable electron donor for sulfate-reducing processes at a maximal temperature of 70 °C, with sulfide as the sole mineralization product of methanol degradation at that temperature. [source]