•Ecotoxicological effects of SDZ and SMX on the microalgae-bacteria consortium were evaluated.•Intracellular antioxidant enzymes and pigments were influenced by SDZ and SMX.•EPS was shown to be ...associated with granule formation in presence of SDZ.•The bacterial community in the presence of SAs was identified by high throughput sequencing.•CAT and POD played a crucial role in intracellular sulfonamides biodegradation.
Antibiotics in wastewaters (e.g., sulfonamides (SAs)) are not effectively removed by the conventional bacterial processes. In this study, a microalgae (Scenedesmus obliquus)-based process was evaluated for the removal of SAs. The maximum removal efficiency of sulfadiazine (SDZ) and sulfamethoxazole (SMX) by the consortium was 5.85% and 40.84%, respectively. The lower SDZ biodegradation efficiency could be due to the difference in the lipophilic degree related to cell binding. The presence of SAs did not significantly inhibit the biomass production of the consortium (1311–1952 mg/L biomass) but led to a 36–51% decrease in total polysaccharide content and an increase in microalgae’s protein content, which caused granule formation. The presence of SMX and SDZ resulted in an increase in lipid peroxidation activity with a 6.2 and 23.5-fold increase in malondialdehyde content, respectively. Rhodobacter and Phreatobacter were abundant in the consortium with SAs’ presence, while alinarimonas, Catalinimonas and Cecembia were seen in their absence.
Microalgal biomass harvested from wastewater treatment high rate algal ponds may be valorised through anaerobic digestion producing biogas. However, microalgae anaerobic biodegradability is limited ...by their complex cell wall structure. Thus, pretreatment techniques are being investigated to improve microalgae methane yield. In the current study, thermal pretreatment at relatively low temperatures of 75–95 °C was effective at enhancing microalgae anaerobic biodegradability; increasing the methane yield by 70% in respect to nonpretreated biomass. Microscopic images showed how the pretreatment damaged microalgae cells, enhancing subsequent anaerobic digestion. Indeed, digestate images showed how after pretreatment only species with resistant cell walls, such as diatoms, continued to be present. Energy balances based on lab-scale reactors performance at 20 days HRT, shifted from neutral to positive (energy gain around 2.7 GJ/d) after thermal pretreatment. In contrast with electricity consuming pretreatment methods, such as microwave irradiation, thermal pretreatment of microalgae seems to be scalable.
Algae contain a number of anti-inflammatory bioactive compounds such as omega-3 polyunsaturated fatty acids (n-3 PUFA) and chlorophyll a, hence as dietary ingredients, their extracts may be effective ...in chronic inflammation-linked metabolic diseases such as cardiovascular disease. In this study, anti-inflammatory potential of lipid extracts from three red seaweeds (Porphyra dioica, Palmaria palmata and Chondrus crispus) and one microalga (Pavlova lutheri) were assessed in lipopolysaccharide (LPS)-stimulated human THP-1 macrophages. Extracts contained 34%-42% total fatty acids as n-3 PUFA and 5%-7% crude extract as pigments, including chlorophyll a, β-carotene and fucoxanthin. Pretreatment of the THP-1 cells with lipid extract from P. palmata inhibited production of the pro-inflammatory cytokines interleukin (IL)-6 (p < 0.05) and IL-8 (p < 0.05) while that of P. lutheri inhibited IL-6 (p < 0.01) production. Quantitative gene expression analysis of a panel of 92 genes linked to inflammatory signaling pathway revealed down-regulation of the expression of 14 pro-inflammatory genes (TLR1, TLR2, TLR4, TLR8, TRAF5, TRAF6, TNFSF18, IL6R, IL23, CCR1, CCR4, CCL17, STAT3, MAP3K1) by the lipid extracts. The lipid extracts effectively inhibited the LPS-induced pro-inflammatory signaling pathways mediated via toll-like receptors, chemokines and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling molecules. These results suggest that lipid extracts from P. lutheri, P. palmata, P. dioica and C. crispus can inhibit LPS-induced inflammatory pathways in human macrophages. Therefore, algal lipid extracts should be further explored as anti-inflammatory ingredients for chronic inflammation-linked metabolic diseases.
•Growth of microalgae on mixed municipal and industrial wastewater.•High nitrogen and phosphorus removal was achieved in all treatments.•Selenastrum minutum had the highest biomass and lipids ...yields.•Lipid content was negatively correlated to the nitrogen concentration.•Mixtures of wastewater have great potential to produce algal biomass and lipid.
The aim of the study was to grow microalgae on mixed municipal and industrial wastewater to simultaneously treat the wastewater and produce biomass and lipids. All algal strains grew in all wastewater mixtures; however, Selenastrum minutum had the highest biomass and lipids yields, up to 37% of the dry matter. Nitrogen and phosphorus removal were high and followed a similar trend in all three strains. Ammonium was reduced from 96% to 99%; this reduction was due to algal growth and not to stripping to the atmosphere, as confirmed by the amount of nitrogen in the dry algal biomass. Phosphate was reduced from 91% to 99%. In all strains used the lipid content was negatively correlated to the nitrogen concentration in the algal biomass. Mixtures of pulp and paper wastewater with municipal and dairy wastewater have great potential to grow algae for biomass and lipid production together with effective wastewater treatment.
In lightly polluted water containing heavy metals, organic matter, and green microalgae, the molecular weight of organic matter may influence both the growth of green microalgae and the concentration ...of heavy metals. This study elucidates the effects and mechanisms by which different molecular weight fractions of fulvic acid (FA), a model dissolved organic matter component, facilitate the bioaccumulation of hexavalent chromium (Cr(VI)) in a typical green alga, Chlorella vulgaris. Findings show that the addition of FA fractions with molecular weights greater than 10 kDa significantly enhances the enrichment of total chromium and Cr(VI) in algal cells, reaching 21.58%−31.09 % and 16.17 %−22.63 %, respectively. Conversely, the efficiency of chromium enrichment in algal cells was found to decrease with decreasing molecular weight of FA. FA molecular weight within the range of 0.22 µm-30 kDa facilitated chromium enrichment primarily through the algal organic matter (AOM) pathway, with minor contributions from the algal cell proliferation and extracellular polymeric substances (EPS) pathways. However, with decreasing FA molecular weight, the AOM and EPS pathways become less prominent, whereas the algal cell proliferation pathway becomes dominant. These findings provide new insights into the mechanism of chromium enrichment in green algae enhanced by medium molecular weight FA.
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•The removal of Cr by C. vulgaris decreases with decreasing FA molecular weight•FA fraction (0.22 µm-30 kDa) exhibits highest bioavailability, lipid, EPS contents•Medium molecular weight FA facilitate algal AOM contribution of 75 % Cr(VI) removal
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•Engine performance suffers slightly with addition spirulina microalgae to diesel.•NOX trade-off can be overcome with suitable spirulina microalgae and its blends.•The smoke and PM ...emission is reduced using spirulina biodiesel compared to diesel.
This research, the effects of the spirulina microalgae biodiesel (SMB) blends containing 20, 40, 60 and 80% in volume based were investigated in a naturally aspirated diesel engine at various loads. The performance, combustion and emission analyses showed that of the injection timings (23.0° b TDC) with higher injection pressure of 220 bar. The results show that SMB1 (20% of spirulina microalgae biodiesel and 80% diesel) produces lower exhaust emission and cylinder pressures, brake thermal efficiency (BTE), exhaust temperature and maximum rise pressure rates as compared to diesel fuel. Specific fuel consumption and ignition delay period results increased up to 3.3%, 8.2% and BTE reduced up to 3.03% when the spirulina microalgae blend was increased to 20% at the higher load. The SMB blends also resulted in lower nitrogen oxides (NOX) emission by 4.9%, particulate matter (PM) emission by 20.7% as well as lower smoke by 5.4%, but CO2 emissions increased for all loads. The results showed that addition spirulina microalgae produced a lower of brake thermal efficiency and exhaust temperature, the CO2 emission were improved. Hence, spirulina microalgae can be used in diesel engine.
The discharge of rare earth element (REE) tailings wastewater results in serious ecological deterioration and health risk, due to high ammonia nitrogen, and strong acidity. The low C/N ratio makes it ...recalcitrant to biodegradation. Recently it has been shown that microalgal technology has a promising potential for the simultaneous harsh wastewater treatment and resource recovery. However, the low nitrogen removal rate and less biomass of microalgae restricted its development. In this work, Chlorococcum sp. was successfully isolated from the rare earth mine effluent. The microalgae was capable of enhancing nitrogen contaminants removal from REEs wastewater due to the carbonate addition, which simulated the activity increase of carbonic anhydrase (CA). The total inorganic nitrogen (TIN) removal rate reached 4.45 mg/L h−1, which compared to other microalgal species, the nitrogen removal rate and biomass yield were 7.8- and 4.9-fold higher, respectively. Notably, high lipid contents (mainly triglycerides, 43.85% of dry weight) and a high biomass yield were obtained. Meanwhile, the microalgae had an excellent settleability attributed to higher extracellular polymeric substance (EPS) formation, leading to easier resource harvest. These results were further confirmed in a continuous-flow photobioreactor with a stable operation for more than 30 days, indicating its potential for application.
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•Resourceful treatment of harsh high-nitrogen REEs wastewater is first achieved.•Carbonate activated Chlorococcum sp. microalgae enhances NH4+-N and TIN removal.•The microalgae shows an excellent settle ability and biomass yield.•The carbonate activated microalgae photobioreactor is stably operated.
•Lutein production from marigold flowers and from microalgae is compared.•Lutein production rate of microalgae is 3–6 times higher than marigold flowers.•Lutein from marigold consumed more land and ...water, but less nutrients and power.•R&D needs for affordable microalgae lutein production industries are discussed.
Microalgae have faster growth rates and more free lutein than marigold flowers, the current source of lutein. However, no commercial lutein production uses microalgae. This review compares lutein content, cultivation, harvesting, cell disruption, and extraction stages of lutein production using marigold flowers and those using microalgae as feedstock. The lutein production rate of microalgae is 3–6 times higher than that of marigold flowers. To produce 1kg of pure lutein, marigolds need more land and water, but require less nutrients (N, P, K) and less energy than microalgae. Since lutein is tightly bound in microalgae and microalgae are small, cell disruption and subsequent extraction stages consume a considerable amount of energy. Research and development of affordable lutein production from microalgae are discussed.
Biodiesel has received much attention in recent years. Although numerous reports are available on the production of biodiesel from vegetable oils of terraneous oil-plants, such as soybean, sunflower ...and palm oils, the production of biodiesel from microalgae is a newly emerging field. Microalgal biotechnology appears to possess high potential for biodiesel production because a significant increase in lipid content of microalgae is now possible through heterotrophic cultivation and genetic engineering approaches. This paper provides an overview of the technologies in the production of biodiesel from microalgae, including the various modes of cultivation for the production of oil-rich microalgal biomass, as well as the subsequent downstream processing for biodiesel production. The advances and prospects of using microalgal biotechnology for biodiesel production are discussed.
The use of high-throughput sequencing technologies with the 16S rRNA gene for characterization of bacterial and archaeal communities has become routine. However, the adoption of sequencing methods ...for eukaryotes has been slow, despite their significance to natural and engineered systems. There are large variations among the target genes used for amplicon sequencing, and for the 18S rRNA gene, there is no consensus on which hypervariable region provides the most suitable representation of diversity. Additionally, it is unclear how much PCR/sequencing bias affects the depiction of community structure using current primers. The present study amplified the V4 and V8-V9 regions from seven microalgal mock communities as well as eukaryotic communities from freshwater, coastal, and wastewater samples to examine the effect of PCR/sequencing bias on community structure and membership. We found that degeneracies on the 3' end of the current V4-specific primers impact read length and mean relative abundance. Furthermore, the PCR/sequencing error is markedly higher for GC-rich members than for communities with balanced GC content. Importantly, the V4 region failed to reliably capture 2 of the 12 mock community members, and the V8-V9 hypervariable region more accurately represents mean relative abundance and alpha and beta diversity. Overall, the V4 and V8-V9 regions show similar community representations over freshwater, coastal, and wastewater environments, but specific samples show markedly different communities. These results indicate that multiple primer sets may be advantageous for gaining a more complete understanding of community structure and highlight the importance of including mock communities composed of species of interest.
The quantification of error associated with community representation by amplicon sequencing is a critical challenge that is often ignored. When target genes are amplified using currently available primers, differential amplification efficiencies result in inaccurate estimates of community structure. The extent to which amplification bias affects community representation and the accuracy with which different gene targets represent community structure are not known. As a result, there is no consensus on which region provides the most suitable representation of diversity for eukaryotes. This study determined the accuracy with which commonly used 18S rRNA gene primer sets represent community structure and identified particular biases related to PCR amplification and Illumina MiSeq sequencing in order to more accurately study eukaryotic microbial communities.
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