| 1. |
- Adeboye, Peter, 1982, et al.
(författare)
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A coniferyl aldehyde dehydrogenase gene from Pseudomonas sp. strain HR199 enhances the conversion of coniferyl aldehyde by Saccharomyces cerevisiae
- 2016
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 212:July 2016, s. 11-19
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Tidskriftsartikel (refereegranskat)abstract
- AbstractThe conversion of coniferyl aldehyde to cinnamic acids by Saccharomyces cerevisiae under aerobic growth conditions was previously observed. Bacteria such as Pseudomonas have been shown to harbor specialized enzymes for converting coniferyl aldehyde but no comparable enzymes have been identified in S. cerevisiae. CALDH from Pseudomonas was expressed in S. cerevisiae. An acetaldehyde dehydrogenase (Ald5) was also hypothesized to be actively involved in the conversion of coniferyl aldehyde under aerobic growth conditions in S. cerevisiae. In a second S. cerevisiae strain, the acetaldehyde dehydrogenase (ALD5) was deleted. A prototrophic control strain was also engineered. The engineered S. cerevisiae strains were cultivated in the presence of 1.1 mM coniferyl aldehyde under aerobic condition in bioreactors. The results confirmed that expression of CALDH increased endogenous conversion of coniferyl aldehyde in S. cerevisiae and ALD5 is actively involved with the conversion of coniferyl aldehyde in S. cerevisiae.
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| 2. |
- Ahlgren, S., et al.
(författare)
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Ammonium nitrate fertiliser production based on biomass : Environmental effects from a life cycle perspective
- 2008
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 99:17, s. 8034-8041
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Tidskriftsartikel (refereegranskat)abstract
- Ammonium nitrate and calcium ammonium nitrate are the most commonly used straight nitrogen fertilisers in Europe, accounting for 43% of the total nitrogen used for fertilisers. They are both produced in a similar way; carbonate can be added as a last step to produce calcium ammonium nitrate. The environmental impact, fossil energy input and land use from using gasified biomass (cereal straw and short rotation willow (Salix) coppice) as feedstock in ammonium nitrate production were studied in a cradle-to-gate evaluation using life cycle assessment methodology. The global warming potential in the biomass systems was only 22-30% of the impact from conventional production using natural gas. The eutrophication potential was higher for the biomass systems due to nutrient leaching during cultivation, while the acidification was about the same in all systems. The primary fossil energy use was calculated to be 1.45 and 1.37 MJ/kg nitrogen for Salix and straw, respectively, compared to 35.14 MJ for natural gas. The biomass production was assumed to be self-supporting with nutrients by returning part of the ammonium nitrate produced together with the ash from the gasification. For the production of nitrogen from Salix, it was calculated that 3914 kg of nitrogen can be produced every year from 1 ha, after that 1.6% of the produced nitrogen has been returned to the Salix production. From wheat straw, 1615 kg of nitrogen can be produced annually from 1 ha, after that 0.6% of the nitrogen has been returned. © 2008 Elsevier Ltd. All rights reserved.
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| 3. |
- Ahlgren, Serina, et al.
(författare)
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Nitrogen fertiliser production based on biogas - Energy input, environmental impact and land use
- 2010
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 101, s. 7181-7184
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present paper was to investigate the land use, environmental impact and fossil energy use when using biogas instead of natural gas in the production of nitrogen fertilisers The biogas was assumed to be produced from anaerobic digestion of ley grass and maize. The calculations showed that 1 ha of agricultural land in south-west Sweden can produce 1.7 metric ton of nitrogen in the form of ammonium nitrate per year from ley grass, or 3 6 ton from maize The impact on global warming, from cradle to gate, was calculated to be lower when producing nitrogen fertiliser from biomass compared with natural gas Eutrophication and acidification potential was higher in the biomass scenarios The greatest advantage of the biomass systems however lies in the potential to reduce agriculture's dependency on fossil fuels In the biomass scenarios, only 2-4 MJ of primary fossil energy was required, while 35 MJ/kg N was required when utilising natural gas (C) 2010 Elsevier Ltd All rights reserved
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| 4. |
- Akerberg, C, et al.
(författare)
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An economic evaluation of the fermentative production of lactic acid from wheat flour
- 2000
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Ingår i: Bioresource Technology. - 1873-2976. ; 75:2, s. 119-126
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Tidskriftsartikel (refereegranskat)abstract
- A process for the fermentative production of lactic acid from whole-wheat flour consisting of starch and bran containing nutrients is presented and an economical evaluation of the lactic acid production cost performed. Bottlenecks were identified and alternative processes were evaluated and compared. The costs of raw material, the sodium hydroxide in the fermentation step, and the conversion of lactate to lactic acid using electrodialysis were found to contribute considerably to the total production cost. Performing the fermentation step as a batchwise step was economically better than continuous fermentation. The lactic acid production cost can be reduced by lowering the pH and/or by recycling the sodium hydroxide produced by electrodialysis to the fermentor. Using higher wheat flour concentrations reduced the lactic acid production cost and numerical optimisation of the process, with respect to the wheat flour concentration, showed that the optimal concentration corresponded to 116 g glucose/l, which resulted in a production cost of 0.833 US$/kg product. A Monte Carlo simulation of the total production cost for this concentration when the investment and operational cost and the price of the raw material were varied showed that the probability that the production cost could be lower than 0.90 or 1.0 US$/kg was 61% or 91%, respectively. (C) 2000 Elsevier Science Ltd. All rights reserved.
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| 5. |
- Almeida, Joao, et al.
(författare)
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Screening of Saccharomyces cerevisiae strains with respect to anaerobic growth in non-detoxified lignocellulose hydrolysate.
- 2009
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Ingår i: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 100, s. 3674-3677
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Tidskriftsartikel (refereegranskat)abstract
- A microplate screening method was used to assess anaerobic growth of 12 Saccharomyces cerevisiae strains in barley straw, spruce and wheat straw hydrolysate. The assay demonstrated significant differences in inhibitor tolerance among the strains. In addition, growth inhibition by the three hydrolysates differed so that wheat hydrolysate supported growth up to 70%, while barley hydrolysate only supported growth up to 50%, with dilute-acid spruce hydrolysate taking an intermediate position.
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| 6. |
- Alriksson, Björn, et al.
(författare)
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Improving the fermentability of enzymatic hydrolysates of lignocellulose through chemical in-situ detoxification with reducing agents
- 2011
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Ingår i: Bioresource Technology. - : Elsevier Ltd. - 0960-8524 .- 1873-2976. ; 102:2, s. 1254-1263
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Tidskriftsartikel (refereegranskat)abstract
- Inhibitory lignocellulose hydrolysates were treated with the reducing agents dithionite and sulfite to achieve improved fermentability. Addition of these reducing agents (in the concentration range 5.0-17.5mM) to enzymatic hydrolysates of spruce wood or sugarcane bagasse improved processes based on both SHF (simultaneous hydrolysis and fermentation) and SSF (simultaneous saccharification and fermentation). The approach was exemplified in ethanolic fermentations with Saccharomyces cerevisiae and by using hydrolysates with sugar concentrations >100g/L (for SHF) and with 10% dry-matter content (for SSF). In the SHF experiments, treatments with dithionite raised the ethanol productivities of the spruce hydrolysate from 0.2 to 2.5g×L(-1)×h(-1) and of the bagasse hydrolysate from 0.9 to 3.9g×L(-1)×h(-1), values even higher than those of fermentations with reference sugar solutions without inhibitors. Benefits of the approach include that the addition of the reducing agent can be made in-situ directly in the fermentation vessel, that the treatment can be performed at a temperature and pH suitable for fermentation, and that the treatment results in dramatically improved fermentability without degradation of fermentable sugars. The many benefits and the simplicity of the approach offer a new way to achieve more efficient manufacture of fermentation products from lignocellulose hydrolysates.
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| 7. |
- Alvarez, Rene, et al.
(författare)
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The effect of temperature variation on biomethanation at high altitude.
- 2008
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Ingår i: Bioresource Technology. - : Elsevier BV. - 1873-2976 .- 0960-8524. ; 99, s. 7278-7284
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the current study was to examine effects of daily temperature variations on the performance of anaerobic digestion. Forced square-wave temperature variations (between 11 and 25, 15 and 28, and 19 and 32 degrees C) were imposed on a bench-scale digester using a mixture of llama-cow-sheep manure in a semi-continuous process. The volumetric biogas production rate, methane yield, and the volatile solid reductions were compared with the results obtained from anaerobic digestion (AD) at constant temperatures. The forced cyclic variations of temperature caused large cyclic variations in the rate of gas production and the methane content. As much as 94-97% of the daily biogas was obtained in the 12h half-cycle at high temperature. The values for volumetric biogas production rate and methane yield increased at higher temperatures. The average volumetric biogas production rate for cyclic operation between 11 and 25 degrees C was 0.22Ld(-1)L(-1) with a yield of 0.07m(3)CH(4)kg(-1) VS added (VSadd), whereas for operation between 15 and 29 degrees C the volumetric biogas production rate increased by 25% (to 0.27Ld(-1)L(-1) with a yield of 0.08m(3)CH(4)kg(-1) VSadd). In the highest temperature region a further increase of 7% in biogas production was found and the methane yield was 0.089m(3)CH(4)kg(-1) VSadd. The employed digester showed an immediate response when the temperature was elevated, which indicates a well-maintained metabolic capacity of the methanogenic bacteria during the period of low temperature. Overall, periodic temperature variations appear to give less decrease in process performance than a priori anticipated.
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| 8. |
- Andersson, B E, et al.
(författare)
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Growth of inoculated white-rot fungi and their interactions with the bacterial community in soil contaminated with polycyclic aromatic hydrocarbons, as measured by phospholipid fatty acids
- 2000
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Ingår i: Bioresource Technology. - 1873-2976. ; 73:1, s. 29-36
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to examine the possibility of measuring the growth of three white-rot fungi in soil contaminated with polycyclic aromatic hydrocarbons (PAHs), by estimating the soil levels of the phospholipid fatty acid (PLFA) 18:2ω6,9. The effect of the fungi on the PAH concentration and on the indigenous bacterial population in the soil was monitored. As shown by visual examination, the fungi investigated, Pleurotus ostreatus, Phanerochaete chrysoporium and Hypholoma fasciculare, grew well in autoclaved soil, whilst only H. fasciculare grew in non-autoclaved soil. In these reactors, there was also detected an increase in the PLFA 18:2ω6,9. However, the interpretation of the PLFA data was somewhat disturbed since 18:2ω6,9 also was found to be present in the birch wood used as a fungal substrate. In autoclaved soil, P. ostreatus and P. chrysosporium were found to exhibit a PAH-degrading capability, with the total PAH concentration decreasing from 209±35 and 186±2 to 149±6 and 109±6 mg/kg dry weight (dw) soil, respectively, during the 10 week incubation period. No PAH-degradation could be detected in any treatment using non-autoclaved soil. In the autoclaved soil, the total level of bacterial specific PLFAs in all fungal treatments, and in a control using added ground birch sticks, was found to be lowered. In the non-autoclaved soil, 6 out of 9 selected bacterial PLFAs exhibited a significant change between the treatments, but the overall total content of bacterial PLFAs did not change. The present study has shown that it is possible to measure fungal growth in a PAH-contaminated soil derived from a former gasworks plant by estimating the levels of the PLFA 18:2ω6,9. The inoculated fungi affected the indigenous bacteria, as shown by estimating the level of bacterial specific PLFAs. Finally, fungal PAH-degradation could be detected in autoclaved soil but not in non-autoclaved soil.
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| 9. |
- Andersson, B E, et al.
(författare)
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Three-dimensional outgrowth of a wood-rotting fungus added to a contaminated soil from a former gasworks site
- 2001
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Ingår i: Bioresource Technology. - 1873-2976. ; 78:1, s. 37-45
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Tidskriftsartikel (refereegranskat)abstract
- The capability of wood-rotting fungi (WRF) to colonise contaminated soil is an important fungal characteristic in the development of WRF-based soil bioremediation, it is also important to have methods that monitor the presence of the WRF in the soil. In this lab-scale study, it was shown that it was possible to re-capture, localise and identify a brown-rot fungus, Antrodia vaillantii, after it has been inoculated into, and grown in, a contaminated soil from a former gasworks site. The three-dimensional outgrowth of A. vaillantii was monitored by allowing it to grow into fungicide-treated wood baits, temporarily placed in the soil. After two weeks, the baits were withdrawn from the soil and surface sterilised with hydrogen peroxide to favour fungi growing inside baits, i.e., A. vaillantii. After subsequent plating of baits on selective agar medium the presence of A. vaillantii was confirmed with PCR/RFLP. A. vaillantii was found to be viable throughout the 54 days long study and exhibited a surface growth pattern similar to other well-known cord-forming basidiomycetes. Firstly, the upper part of the soil closest to the place of inoculation was colonised, however, over a period of time, the area of colonisation spread deeper into the soil. The detection method employed in the current study gave a conservative estimate of the fungal proliferation and did not require extensive sampling. Its use could be applicable in both applied research, such as soil bioremediation, and in pure microbial ecology studies.
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| 10. |
- Andersson, Jonatan, et al.
(författare)
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Evaluation of straw as a biofilm carrier in the methanogenic stage of two-stage anaerobic digestion of crop residues
- 2002
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Ingår i: Bioresource Technology. - 1873-2976. ; 85:1, s. 51-56
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Tidskriftsartikel (refereegranskat)abstract
- Straw was evaluated as a biofilm carrier in the methanogenic stage of the two-stage anaerobic digestion of crop residues. Three reactor configurations were studied, a straw-packed-bed reactor, a glass packed-bed reactor and a reactor containing suspended plastic carriers. The reactor with the packed straw bed showed the best results. It had the highest methane production, 5.4 11(-1) d(-1), and the chemical oxygen demand (COD) removal ranged from 73-50% at organic loading rates from 2.4-25 g COD 1(-1) d(-1). The degradation pattern of volatile fatty acids showed that the degradation of propionate and longer-chain fatty acids was limiting at higher organic loading rates. A stable effluent pH showed that the packed-bed reactors had good ability to withstand the variations in load and volatile fatty acid concentrations that can occur in the two-stage process. The conclusion is that straw would work very well in the intended application. A further benefit is that straw is a common agricultural waste product and requires only limited resources concerning handling and cost. (C) 2002 Elsevier Science Ltd. All rights reserved.
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