| 1. |
- Bizjak, Tinkara, et al.
(author)
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Presence and activity of nitrogen-fixing bacteria in Scots pine needles in a boreal forest : a nitrogen-addition experiment
- 2023
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In: Tree Physiology. - : Oxford University Press. - 0829-318X .- 1758-4469. ; 43:8, s. 1354-1364
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Journal article (peer-reviewed)abstract
- Endophytic nitrogen-fixing bacteria have been detected and isolated from the needles of conifer trees growing in North American boreal forests. Because boreal forests are nutrient-limited, these bacteria could provide an important source of nitrogen for tree species. This study aimed to determine their presence and activity in a Scandinavian boreal forest, using immunodetection of nitrogenase enzyme subunits and acetylene-reduction assays of native Scots pine (Pinus sylvestris L.) needles. The presence and rate of nitrogen fixation by endophytic bacteria were compared between control plots and fertilized plots in a nitrogen-addition experiment. In contrast to the expectation that nitrogen-fixation rates would decline in fertilized plots, as seen, for instance, with nitrogen-fixing bacteria associated with bryophytes, there was no difference in the presence or activity of nitrogen-fixing bacteria between the two treatments. The extrapolated calculated rate of nitrogen fixation relevant for the forest stand was 20 g N ha-1 year-1, which is rather low compared with Scots pine annual nitrogen use but could be important for the nitrogen-poor forest in the long term. In addition, of 13 colonies of potential nitrogen-fixing bacteria isolated from the needles on nitrogen-free media, 10 showed in vitro nitrogen fixation. In summary, 16S rRNA sequencing identified the species as belonging to the genera Bacillus, Variovorax, Novosphingobium, Sphingomonas, Microbacterium and Priestia, which was confirmed by Illumina whole-genome sequencing. Our results confirm the presence of endophytic nitrogen-fixing bacteria in Scots pine needles and suggest that they could be important for the long-term nitrogen budget of the Scandinavian boreal forest.
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| 2. |
- Das, Santanu, et al.
(author)
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Comparative study of bioenzyme production using submerged fermentation on different agricultural wastes on ligninase producing from wood rot fungi isolated from Pushpagiri and Brahmagiri Hills of Karnataka
- 2020
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In: Journal of Advanced Research in Dynamical and Control Systems. - : Institute of Advanced Scientific Research. - 1943-023X. ; 12:7 Special Issue, s. 1562-1569
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Journal article (peer-reviewed)abstract
- A total of 132 White rot fungus were isolated from the wood bark samples, collected from the different locations in the Western Ghats region of Karnataka and screened for Ligninolytic enzyme production. Ten strains exhibiting maximum activity numbered 30, 40, 41, 61, 76, 86, 104, 113, 123 and 124 were further screened under submerged fermentation using agricultural wastes for enzyme production activity. Among the four substrates used (Sawdust, Paddy straw, Pongamia leaf, Kitchen Vegetable waste), highest lignin peroxidase activity was seen in Pongamia with strain 75 (0.766 U/ml) and minimum was in Paddy straw with strain 124(0.003 U/ml). Highest Manganese Peroxide content was seen in sawdust with strain 40 (1.014 U/ml) and minimum was in vegetable waste strain 75 (0.150 U/ml). Highest laccase activity was in Pongamia leafwith strain 123 (0.375 U/ml) and lowest was in Paddy straw strain (75)(0.012 U/ml).Highest versatile peroxidase activity was observed in Pongamia strain 113(0.504 U/ml) and lowest in Paddy straw strain 61 (0.023 U/ml). Cellulase content was highest with Pongamia using strain 41 (0.032 U/ml)and lowest in Paddy straw with strains61, 104, 113, 124 (0.003 U/ml).Highest Protein content was present in Pongamia degradation with strain 104(0.246 U/ml) and lowest was in Paddy straw with strain 113 (0.059 U/ml).The maximum enzyme activity of laccase by wood rot fungal strains 30, 40, 41, 61, 76, 86, 104, 113, 123 and 124 strains were obtained on the 8th day of fermentation wherein Manganese peroxidase and lignin peroxidase showed the highest activity on the 10th day of fermentation.
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| 3. |
- Das, Santanu, et al.
(author)
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Optimization of biofuel production by molecular characterization of ligninase enzyme isolated from wood rot fungi in Pushpagiri and Brahmagiri Hills in Karnataka by using RAPD molecular markers
- 2020
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In: Journal of green engineering. - : Alpha Publishers. - 1904-4720 .- 2245-4586. ; 10:6, s. 2560-2597
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Journal article (peer-reviewed)abstract
- Wood rot fungi are one of the major degraders in the biosphere that help in degrading most of the plant origin polymers like cellulose, hemicellulose and lignin. Lignin is the second most abundant aromatic compound found in plant cell that holds up cellulose and hemicellulose. There is a lot of emphasis that is being put on the fungal degradation of lignin using wood and other lignocellulosic as a renewable source in the production of chemicals, paper products, feeds and fuels and the use of fungi as one of the most potent sources of degrading organisms. In the present study, screening for lignin degrading enzymes were done with 132 isolates and the maximum enzyme producing strains of 10 wood rot fungi samples were taken for molecular characterization using RAPD molecular markers.Isolation of genomic DNA of the 10 wood rot fungi samples was done using phenolchloroform method and quantified on agarose gel. The obtained genomic DNA was further subjected tocharacterization using RAPD-PCR method with 06 random primers OPA2, OPA5, OPA7, OPA8, OPD3 and OPC2. The amplified PCR products were analyzed by Agarose Gel Electrophoresis and were observed under UV Transilluminator. Analysis of the base pairs of the bands was done by Bio-Rad Gel Doc system.A total of 172 fragments were generated in the 10 isolates with 6 primers. Dendrogram analyses of the gels were done which gave a close relation of each DNA samples. The results indicate that some strains were genetically more similar and few diverse. The current study shows samples 30, 40, 41, 113 and 124 are genetically closely related.
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| 4. |
- Harinikumar, K. M., et al.
(author)
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Bioethanol production from four abundant Indian agricultural wastes
- 2020
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In: Biofuels. - : Taylor & Francis. - 1759-7269 .- 1759-7277. ; 11:5, s. 607-613
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Journal article (peer-reviewed)abstract
- Lignocellulose feedstocks are promising second-generation sources of ethanol biofuel. They include massive amounts of agricultural waste generated in India, much of which is currently burnt (exacerbating major pollution problems), but could potentially be fermented. To assist efforts to realize this potential, four abundant kinds of Indian agricultural residues (sugarcane bagasse and straw from rice, sweet sorghum and millet) were hydrolyzed via a dilute-acid method and fermented at 27 °C, using the white-rot fungus Trametes versicolor as a biocatalyst. The total carbohydrate contents of the agriculture wastes were analyzed, as well as soluble sugar contents of the hydrolysates at the start and end of the fermentations; their ethanol yields and activities of the key enzymes aldehyde dehydrogenase and pyruvate decarboxylase were also measured. Results show that ca. 85–90% of the fermentable sugars were used for ethanol production, and the enzyme activities are consistent with the observed yields. The findings indicate a great potential for ethanol production from Indian agricultural waste.
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| 5. |
- Herrera-Belaroussi, Aude, et al.
(author)
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Candidatus Frankia nodulisporulans sp. nov., an Alnus glutinosa-infective Frankia species unable to grow in pure culture and able to sporulate in-planta
- 2020
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In: Systematic and Applied Microbiology. - : Elsevier BV. - 0723-2020 .- 1618-0984. ; 43:6
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Journal article (peer-reviewed)abstract
- We describe a new Frankia species, for three non-isolated strains obtained from Alnus glutinosa in France and Sweden, respectively. These strains can nodulate several Alnus species (A. glutinosa, A. incana, A. alno-betula), they form hyphae, vesicles and sporangia in the root nodule cortex but have resisted all attempts at isolation in pure culture. Their genomes have been sequenced, they are significantly smaller than those of other Alnus-infective species (5 Mb instead of 7.5 Mb) and are very closely related to one another (ANI of 100%). The name Candidatus Frankia nodulisporulans is proposed.
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| 6. |
- Kawde, Anurag, 1984-, et al.
(author)
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More than protection : the function of TiO2 interlayers in hematite functionalized Si photoanodes
- 2020
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In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 22:48, s. 28459-28467
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Journal article (peer-reviewed)abstract
- Worldwide significant efforts are ongoing to develop devices that store solar energy as fuels. In one such approach, solar energy is absorbed by semiconductors and utilized directly by catalysts at their surfaces to split water into H2 and O2. To protect the semiconductors in these photo-electrochemical cells (PEC) from corrosion, frequently thin TiO2 interlayers are applied. Employing a well-performing photoanode comprised of 1-D n-Si microwires (MWs) covered with a mesoporous (mp) TiO2 interlayer fabricated by solution processing and functionalized with α-Fe2O3 nanorods, we studied here the function of this TiO2 interlayer by high-energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) spectroscopy, along with X-ray emission spectroscopy (XES) and standard characterization techniques. Our data reveal that the TiO2 interlayer not only protects the n-Si MW surface from corrosion, but that it also acts as a template for the hydrothermal growth of α-Fe2O3 nanorods and improves the photocatalytic efficiency. We show that the latter effect correlates with the presence of stable oxygen vacancies at the interface between mp-TiO2 and α-Fe2O3, which act as electron traps and thereby substantially reduce the charge recombination rate at the hematite surface.
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| 7. |
- Lindberg, A., et al.
(author)
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Cold stress stimulates algae to produce value-added compounds
- 2022
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In: Bioresource Technology Reports. - : Elsevier. - 2589-014X. ; 19
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Journal article (peer-reviewed)abstract
- Two cold-tolerant microalgae, Chlorella vulgaris and Scenedesmus sp., were grown at 22 and 5 °C. At the lower temperature, the microalgae showed substantial biochemical and morphological changes. The soluble sugar profile in response to low-temperature cultivation was very different in the two strains. C. vulgaris increased both the sucrose and raffinose family oligosaccharides (RFOs) content at 5 °C while Scenedesmus sp. drastically reduced the sucrose content. Both strains increased the total fatty acid methyl ester (FAME) content when grown at 5 °C. However, the FAME profiles were very different: C. vulgaris mainly increased C18:1 and less so C18:3, while Scenedesmus sp. decreased C18:1 but greatly increased C18:3. The morphology of C. vulgaris changed slightly at the lower temperature, while Scenedesmus sp. showed substantial changes in the size and shape. Low temperature triggered the synthesis of unsaturated fatty acids that are essential for human nutrition.
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| 8. |
- Nzayisenga, Jean Claude, 1986-
(author)
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Autotrophic and heterotrophic culture of Nordic microalgae in wastewater for lipid production
- 2020
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Doctoral thesis (other academic/artistic)abstract
- It is well established that society’s main means for producing energy, the combustion of fossil fuels, is unsustainable and contributes to global warming. Microalgae have high potential for the production of biodiesel and energy source that can at least partially replace fossil fuels. In addition, microalgae are a valuable resource for cleaning up the wastewater that developed societies produce on a daily basis. The research presented in this thesis covers how various growth conditions affect the production of lipids – potential energy source – in Nordic microalgae species, and how these species can benefit municipal wastewater treatment.The research presented in Paper 1 demonstrated that the combination of Fourier-Transform IR (FTIR) and Multivariate Curve Resolution-Alternating Least Squares (MCRALS) is a powerful tool for monitoring changes in the biochemical composition (lipids, carbohydrates and proteins) of microalgae grown under different conditions. Experiments showed that Chlorella sp. isolated from Umeå was able to grow under heterotrophic conditions using glycerol as a carbon source and, more importantly, demonstrated high lipid content. The substantial accumulation of lipids observed in Chlorella sp. corresponded to a decrease in carbohydrate content. Paper 2 covered the key metabolites associated with the observed high lipid content under heterotrophic conditions. The low carbohydrate content observed under these growth conditions may be linked to low levels of the metabolites involved in gluconeogenesis. Conversely, the increase in lipid content may be associated with an increase in fatty acid metabolites and/or certain amino acids. The research presented in Paper 3 showed that microalgae grown under high light intensity (300 μE m−2 s−1 ) have higher lipid contents than microalgae grown under low light intensities (50 and 100 μE m−2 s−1). The increase in lipid content under high light intensity conditions corresponded with a decrease in protein content. The research described in paper 4 demonstrated that among various Nordic strains, Desmodesmus sp. is the best candidate for biomass and lipid production under heterotrophic conditions with glycerol as the carbon source. Furthermore, the research covered in Papers 1, 3 and 4 demonstrated that the increase in lipid content under certain growth conditions corresponded to better biodiesel quality based on fatty acid composition. The experiments described in Papers 1,3 and 4 also showed that microalgae were able to remove most of nitrogen and phosphorus in wastewater, and thus, could be beneficial to municipal wastewater treatment plants.In summary, we showed that coupling FTIR to MCR-ALS is useful for evaluating changes in the biochemical composition of microalgae. Nordic microalgae were able to produce high amounts of lipids, which showed a favorable fatty acid profile in terms of biodiesel quality, under certain growth conditions. Subsequent analyses provided insight into which metabolites were responsible for the observed changes in lipid accumulation. We also showed that Nordic microalgae can contribute to wastewater treatment.
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| 9. |
- Nzayisenga, Jean Claude, et al.
(author)
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Effects of light intensity on growth and lipid production in microalgae grown in wastewater
- 2020
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In: Biotechnology for Biofuels. - : BMC. - 1754-6834. ; 13:1
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Journal article (peer-reviewed)abstract
- BackgroundCultivation of microalgae in wastewater could significantly contribute to wastewater treatment, biodiesel production, and thus the transition to renewable energy. However, more information on effects of environmental factors, including light intensity, on their growth and composition (particularly fatty acid contents) is required. Therefore, we investigated the biomass and fatty acid production of four microalgal species, isolated in the Northern hemisphere and grown at three light intensities (50, 150 and 300 mu E m(-2) s(-1)).ResultsIncreases in light intensities resulted in higher biomass of all four species and, importantly, raised fatty acid contents of both Desmodesmus sp. and Scenedesmus obliquus. Fourier-transform IR spectrometry analysis showed that the increases in fatty acid content were associated with reductions in protein, but not carbohydrate, contents. Assessment of fatty acid composition revealed that increasing light intensity led to higher and lower contents of oleic (18:1) and linolenic (18:3) acids, respectively. The microalgae consumed more than 75% of the nitrogen and phosphorus present in the wastewater used as growth medium.ConclusionThe results show the importance of optimizing light intensities to improve fatty acid production by microalgae and their quality as sources of biodiesel. In addition, increase in fatty acid content is associated with decrease in protein content.
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| 10. |
- Nzayisenga, Jean Claude, et al.
(author)
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Metabolomic Study of Heterotrophically Grown Chlorella sp. Isolated from Wastewater in Northern Sweden
- 2021
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In: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 26:9
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Journal article (peer-reviewed)abstract
- There are numerous strains of Chlorella with a corresponding variety of metabolic pathways. A strain we previously isolated from wastewater in northern Sweden can grow heterotrophically as well as autotrophically in light and has higher lipid contents under heterotrophic growth conditions. The aims of the present study were to characterize metabolic changes associated with the higher lipid contents in order to enhance our understanding of lipid production in microalgae and potentially identify new compounds with utility in sustainable development. Inter alia, the amino acids glutamine and lysine were 7-fold more abundant under heterotrophic conditions, the key metabolic intermediate alpha-ketoglutarate was more abundant under heterotrophic conditions with glucose, and maltose was more abundant under heterotrophic conditions with glycerol than under autotrophic conditions. The metabolite 3-hydroxy-butyric acid, the direct precursor of the biodegradable plastic PHB (poly-3-hydroxy-butyric acid), was also more abundant under heterotrophic conditions. Our metabolomic analysis has provided new insights into the alga's lipid production pathways and identified metabolites with potential use in sustainable development, such as the production of renewable, biodegradable plastics, cosmetics, and nutraceuticals, with reduced pollution and improvements in both ecological and human health.
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