| 1. |
- Ferro, Lorenza, 1989-, et al.
(författare)
-
Growth performance and nutrient removal of a Chlorella vulgaris-Rhizobium sp. co-culture during mixotrophic feed-batch cultivation in synthetic wastewater
- 2019
-
Ingår i: Algal Research. - : Elsevier. - 2211-9264. ; 44
-
Tidskriftsartikel (refereegranskat)abstract
- The subarctic green algal strain Chlorella vulgaris 13-1, newly isolated from Northern Sweden, and its co-occurring bacterium Rhizobium sp. were tested for their ability to produce valuable biomass and remove nutrients from synthetic wastewater during mixotrophic feed-batch cultivation at multiple hydraulic retention times (HRTs = 7, 5 and 3 days). The algal-bacterial co-culture showed better performance compared to the corresponding axenic cultures (HRT = 7 days), with a biomass concentration of 0.63 +/- 0.03 g/L and removal rates of 49.5 +/- 6.1% TOC, 55.7 +/- 8.04% TN and 95.6 +/- 3.6% TP at steady-state. Culture stability and a high nutrient removal capacity were recorded in the algal-bacterial co-culture even at HRTs of 5 and 3 days. Interestingly, reducing the HRT from 7 to 5 days resulted in a higher lipid content of the biomass, further reduction of the HRT to 3 days enhanced both daily biomass productivity (1.03 g/L/day) and nutrient assimilation. Mixotrophic co-cultivation of C. vulgaris-Rhizobium sp. can successfully be applied for wastewater reclamation in continuous mode at HRT of 3-7 days, and thus is suitable for both summer and winter conditions in Nordic countries.
|
|
| 2. |
- Ferro, Lorenza, 1989-, et al.
(författare)
-
Statistical Methods for Rapid Quantification of Proteins, Lipids, and Carbohydrates in Nordic Microalgal Species Using ATR-FTIR Spectroscopy
- 2019
-
Ingår i: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 24:18
-
Tidskriftsartikel (refereegranskat)abstract
- Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy is a simple, cheap, and fast method to collect chemical compositional information from microalgae. However, (semi)quantitative evaluation of the collected data can be daunting. In this work, ATR-FTIR spectroscopy was used to monitor changes of protein, lipid, and carbohydrate content in seven green microalgae grown under nitrogen starvation. Three statistical methods-univariate linear regression analysis (ULRA), orthogonal partial least squares (OPLS), and multivariate curve resolution-alternating least squares (MCR-ALS)-were compared in their ability to model and predict the concentration of these compounds in the biomass. OPLS was found superior, since it i) included all three compounds simultaneously; ii) explained variations in the data very well; iii) had excellent prediction accuracy for proteins and lipids, and acceptable for carbohydrates; and iv) was able to discriminate samples based on cultivation stage and type of storage compounds accumulated in the cells. ULRA models worked well for the determination of proteins and lipids, but carbohydrates could only be estimated if already determined protein contents were used for scaling. Results obtained by MCR-ALS were similar to ULRA, however, this method is considerably easier to perform and interpret than the more abstract statistical/chemometric methods. FTIR-spectroscopy-based models allow high-throughput, cost-effective, and rapid estimation of biomass composition of green microalgae.
|
|
| 3. |
- Gojkovic, Zivan, et al.
(författare)
-
Cryogenic X-ray photoelectron spectroscopy determines surface composition of algal cells and gives insights into their spontaneous sedimentation
- 2020
-
Ingår i: Algal Research. - : Elsevier. - 2211-9264. ; 47
-
Tidskriftsartikel (refereegranskat)abstract
- The flotation properties of two green microalgal species isolated from Northern Sweden, Chlorella vulgaris 13-1 and Coelastrella sp. 3-4, were investigated. C. vulgaris 13-1 is a flotating alga that remains suspended in solution during culturing, while Coelastrella sp. 3-4 is readily sedimenting in the stationary growth phase. We were the first to use cryogenic X-ray photoelectron spectroscopy (Cryo-XPS) to gain information on the chemical composition of the algal cell surface and added to these data results obtained from diffuse reflectance - Fourier Transform infrared spectroscopy (DR-FTIR) and classical chemical extractions of carbohydrates, lipids and proteins. Based on the Cryo-XPS data the surface of the sedimenting Coelastrella sp. 3-4 strain is rich in proteins and lipids, while the cell surface of non-flocculating C. vulgaris 13-1 is predominated by carbohydrates, but is poor in lipids. The Zeta-potential of both strains was equally negative. Cell size and the amount of carbohydrates on the algal cell surface, but not the negative surface charge, therefore indicate colloidal stability of microalgae in solutions and can be applied to predict flotation properties of green microalgae.
|
|
| 4. |
- Gojkovic, Zivan, et al.
(författare)
-
Modeling biomass production during progressive nitrogen starvation by North Swedish green microalgae
- 2020
-
Ingår i: Algal Research. - : Elsevier. - 2211-9264. ; 47
-
Tidskriftsartikel (refereegranskat)abstract
- Five newly isolated green algal species from Northern Sweden and one culture collection strain were tested for their ability to remove nitrogen and accumulate carbohydrates and neutral lipids (TAGs) under progressive nitrogen starvation. All six microalgal species increased biomass during N starvation, the amount of proteins decreased, and species dependent either TAGs and/or carbohydrates accumulated. Biomass of the algal strains Coelastrella sp. 3-4, Scenedesmus sp. B2-2 and S. obliquus RISE (UTEX 417) had very low final TAG content (≤3.4%) and high carbohydrate content (>41%) at the end of the starvation period. C. astroideum RW10 accumulated 9.2% TAGs and 53.9% carbohydrates during N-starvation; due to its modest growth rate (1.60 g/L and 1.06 1/day) resulting in low final biomass concentration, its cumulativeTAG and carbohydrate productivity were poor (175 mgTAG/system and 1.03 gCARBS/system). C. vulgaris 13-1 preferentially accumulated TAGs (10.3%) over carbohydrates (35%), with low minimal and maximal N quotas (2.27 and 11.6 mM/gDW) in its biomass and a very high growth rate (1.86 1/day) and cumulative TAGs productivity (278 mgTAG/system). Desmodesmus sp. RUC2 had the highest final biomass concentration (3.48 g/L) as well as cumulative TAG and carbohydrate productivity (269 mgTAG/system and 1.79 gCARBS/system). This species had the lowest minimal and maximal N quotas (1.58 and 8.50 mM/gDW) of all tested species, it can produce high amounts of biomass even when the available nitrogen concentration is low.A Droop's mathematical model with four basic parameters was applied to interpret the experimental data on N assimilation and biomass production under N starvation. The model corresponded well to the experimental data and therefore can successfully be applied to predict biomass production and N assimilation in Nordic algal species.
|
|
| 5. |
- Gojkovic, Zivan, et al.
(författare)
-
Northern green algae have the capacity to remove active pharmaceutical ingredients
- 2019
-
Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier. - 0147-6513 .- 1090-2414. ; 170, s. 644-656
-
Tidskriftsartikel (refereegranskat)abstract
- Eight recently isolated microalgal species from Northern Sweden and the culture collection strain Scenedesmus obliquus RISE (UTEX 417) were tested for their ability to remove 19 pharmaceuticals from growth medium upon cultivation in short light path, flat panel photobioreactors. While the growth of one algal species, Chlorellasorokiniana B1-1, was completely inhibited by the addition of pharmaceuticals, and the one of Scenedesmus sp. B2-2 was strongly inhibited, the other algal strains grew well and produced biomass.In general, lipophilic compounds were removed highly efficient from the culture medium by the microalgae (>70% in average within 2 days). The most lipophilic compounds Biperiden, Trihexyphenidyl, Clomipramine and Amitriptyline significantly accumulated in the biomass of most algal species, with a positive correlation between accumulation and their total biomass content. More persistent in the growth medium were hydrophilic compounds like Caffeine, Fluconazole, Trimetoprim, Codeine, Carbamazepin, Oxazepam and Tramadol, which were detected in amounts of above 60% in average after algal treatment.While Coelastrella sp. 3–4 and Coelastrum astroideum RW10 were most efficient to accumulate certain compounds in their biomass, two algae species, Chlorella vulgaris13-1 and Chlorella saccharophila RNY, were not only highly efficient in removing all 19 pharmaceuticals from the growth medium within 12 days, at the same time only small amounts of these compounds accumulated in their biomass allowing its further use. Chlorella vulgaris 13-1 was able to remove most compounds within 6 days of growth, while Chlorella saccharophila RNY needed 8–10 days.”Wild” Nordic microalgae therefore are able to remove active pharmaceutical ingredients, equally or more efficient than the investigated culture collection strain, thereby demonstrating their possible use in sustainable wastewater reclamation in Nordic conditions.
|
|
| 6. |
- Gojkovic, Zivan, et al.
(författare)
-
The role of microalgae in the biogeochemical cycling of Methylmercury (MeHg) in aquatic environments
- 2022
-
Ingår i: Phycology. - : MDPI. - 2673-9410. ; 2:3, s. 344-362
-
Forskningsöversikt (refereegranskat)abstract
- Methylmercury (MeHg) is the most important and the most abundant organic Hg pollutant in the aquatic ecosystem that can affect human health through biomagnification. It is the most toxic organic Hg form, which occurs naturally and by human-induced contamination in water and is further biomagnified in the aquatic food web. MeHg is the only Hg form that accumulates in living organisms and is able to cross the blood–brain barrier, presenting an enormous health risk. Anthropogenic activity increases eutrophication of coastal waters worldwide, which promotes algae blooms. Microalgae, as primary producers, are especially sensitive to MeHg exposure in water and are an important entrance point for MeHg into the aquatic food web. MeHg assimilated by microalgae is further transferred to fish, wildlife and, eventually, humans as final consumers. MeHg biomagnifies and bioaccumulates in living organisms and has serious negative health effects on humans, especially newborns and children. Knowledge of the microalgae–MeHg interaction at the bottom of the food web provides key insights into the control and prevention of MeHg exposure in humans and wildlife. This review aims to summarize recent findings in the literature on the microalgae–MeHg interaction, which can be used to predict MeHg transfer and toxicity in the aquatic food web.
|
|
| 7. |
- Lage, Sandra, et al.
(författare)
-
Algal Biomass from Wastewater and Flue Gases as a Source of Bioenergy
- 2018
-
Ingår i: Energies. - : MDPI. - 1996-1073. ; 11:3
-
Forskningsöversikt (refereegranskat)abstract
- Algae are without doubt the most productive photosynthetic organisms on Earth; they are highly efficient in converting CO2 and nutrients into biomass. These abilities can be exploited by culturing microalgae from wastewater and flue gases for effective wastewater reclamation. Algae are known to remove nitrogen and phosphorus as well as several organic contaminants including pharmaceuticals from wastewater. Biomass production can even be enhanced by the addition of CO2 originating from flue gases. The algal biomass can then be used as a raw material to produce bioenergy; depending on its composition, various types of biofuels such as biodiesel, biogas, bioethanol, biobutanol or biohydrogen can be obtained. However, algal biomass generated in wastewater and flue gases also contains contaminants which, if not degraded, will end up in the ashes. In this review, the current knowledge on algal biomass production in wastewater and flue gases is summarized; special focus is given to the algal capacity to remove contaminants from wastewater and flue gases, and the consequences when converting this biomass into different types of biofuels.
|
|
| 8. |
- Lindberg, Richard, et al.
(författare)
-
Fate of active pharmaceutical ingredients in a northern high-rate algal pond fed with municipal wastewater
- 2021
-
Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 271
-
Tidskriftsartikel (refereegranskat)abstract
- Active pharmaceutical ingredients (APIs) are vital to human health and welfare, but following therapeutic use, they may pose a potential ecological risk if discharged into the environment. Today's conventional municipal wastewater treatment plants are not designed to remove APIs specifically, and various techniques, preferably cost-effective and environmentally friendly, are being developed and evaluated. Microalgae-based treatment of wastewater is a sustainable and low-cost approach to remove nutrients and emerging contaminants. In this study, a North Sweden high-rate algal pond (HRAP) using municipal untreated wastewater as medium, was investigated in terms of API distribution and fate. Three six-day batches were prepared during 18 days and a total of 36 APIs were quantified within the HRAP of which 14 were removed from the aqueous phase above 50% and seven removed above 90% of their initial concentrations. Twelve APIs of a hydrophobic nature were mostly associated with the algal biomass that was harvested at the end of each batch. HRAPs treatment successfully removed 69% of studied APIs (25 of 36 studied) in six day time. The distribution of various APIs between the aqueous phase and biomass suggested that several removal mechanisms may occur, such as hydrophobicity driven removal, passive biosorption and active bioaccumulation.
|
|
| 9. |
- Martínez, Juan Manuel, et al.
(författare)
-
Use of pulsed electric field permeabilization to extract astaxanthin from the Nordic microalga Haematococcus pluvialis
- 2019
-
Ingår i: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 289
-
Tidskriftsartikel (refereegranskat)abstract
- The Nordic microalgal strain Haematococcus pluvialis was exposed to various stress conditions to induce astaxanthin accumulation. Highest carotenoid content (19.1 mg·g−1dw) was achieved in nitrogen-free culture medium at a high light intensity. The efficiency of Pulsed Electric Field (PEF) pre-treatment of stressed fresh biomass of H. pluvialis followed by incubation in the growth medium was compared to classical disruption methods (bead-beating, freezing-thawing, thermal treatment or ultrasound) for the subsequent extraction of astaxanthin in ethanol. N-starved cells treated with PEF followed by aqueous incubation for 6 h resulted in extraction of 96% (18.3 mgcar·gdw−1) of the total carotenoid content compared to 80% (15.3 mgcar·gdw−1) using other physical methods. The proportion of free forms of astaxanthin was higher in PEF-treated samples compared to mechanical disruption, suggesting PEF triggering an esterase activity. PEF pre-treatment of the cells followed by incubation in growth medium improved astaxanthin extraction in the eco-friendly solvent ethanol.
|
|
| 10. |
- Shchukarev, Andrey, et al.
(författare)
-
Cryo-XPS analysis reveals surface composition of microalgae
- 2020
-
Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 526
-
Tidskriftsartikel (refereegranskat)abstract
- Green microalgae are widely used for wastewater treatment, food/feed and pigment production, as well as for aquaculture. However, very little is known about their surface composition, which can determine algae behavior in nature and influence their processing. In this work, we use cryo-XPS to characterize the surface chemical composition of three different microalgae species. We investigate the applicability of a data treatment method, developed for bacteria, deconvoluting C 1s with respect to protein, lipid and polysaccharide. We discuss how substances unique to algae contribute to the C 1s spectra and how this affects the transferability of the method to microalgae. Two species of green microalgae isolated from Northern Sweden, Chlorella vulgaris 13-1 and Coelastrella sp. 3-4, were compared to reference culture collection strain, Scenedesmus obliquus RISE (UTEX 417). Cryo-XPS data indicate that surfaces of Coelastrella sp. 3-4 and C. vulgaris 13-1 cells are dominated by protein and carbohydrates. However, the carbohydrate content was higher for C. vulgaris. The reference strain shows the highest content of proteins and has an increased amount of lipids compared to the other two. Estimation of the cell surface hydrophobicity suggests that the hydrophobicity increases in the order: C. vulgaris < Coelastrella sp. < S. obliquus.
|
|
