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Oleaginous yeasts utilize renewable resources to produce lipids, which benefits sustainable development, and it is of great interest to screen robust lipid producers. Curvibasidium sp. belongs to nonconventional yeast that are very limitedly studied. Here, two cold-adaptive strains of Curvibasidium sp., namely, Y230 and Y231, isolated from the medicinal lichen Usnea diffracta were investigated for their potential in lipid production. Genome mining of Curvibasidium sp. Y231 was performed, and the special features related to fatty acid biosynthesis were revealed. Glucose, xylose, and glycerol were tested as sole carbon sources for yeast cell growth and lipid production. The total lipid contents of Curvibasidium sp. Y230 and Y231 range from 38.43% to 54.62% of the cell dry cell weight at 20°C, and glucose is the optimal carbon source. These results indicate that the Curvibasidium sp. strains are promising for sustainable lipid production. Our study provides basis for exploration of lichen-derived strains for biotechnological applications, and also benefits utilization of other nonconventional yeasts for sustainable production based on genome-based studies.

Ionic liquids are widely used for lipid and pigment extractions from microalgae. It is possible that ionic liquids are discharged into environments. The evaluation of growth performance and antioxidative response of ionic liquids to microalgae is helpful to explore the stress regulation mechanism and investigate possible environmental risk. Ionic liquids induce production of reactive oxygen species (ROS) to microalgae. These oxidative stresses are possible from cations, anions, and salinity. In this study, the growth inhibitions of [BMIM]Br, [BMIM]Cl, [EMIM]Cl, and [EMIM]EtOSO3 to Anabaena cylindrica, Chlorella pyrenoidesa, and Dunaliella salina were evaluated. It was interesting that Br- and two kinds of cations, [BMIM] and [EMIM], had significant effects on growth inhibitions of these microalgae. IC50 values of these ionic liquids for A. cylindrica, C. pyrenoidesa, and D. salina were also estimated based on the results of growth inhibitions. It was proved that [EMIM]Cl is relatively harmless to C. pyrenoidesa and D. salina, and [EMIM]EtOSO3 is relatively or practically harmless to C. pyrenoidesa. [BMIM]Br and [BMIM]Cl are practically harmless to A. cylindrica and C. pyrenoidesa, and relatively harmless to D. salina. More than 0.8 g/L [EMIM]EtOSO3 led to bleaching of both A. cylindrica and D. salina at 48 h which was shown that the anion, EtOSO3-, had higher inhibition to A. cylindrica and D. salina than Cl-. In addition, high concentration of ionic liquids led to reductions of chlorophyll content in these three kinds of microalgae, increase of ROS levels and malondialdehyde contents for most of the cases. High concentration of ionic liquids also increased the activities of superoxide dismutase in three kinds of microalgae. There were positive correlations between ROS levels or MDA content, and inhibitions ratios of these ionic liquids to microalgae except [EMIM]Cl to A. cylindrica. These antioxidant enzymes were beneficial for reducing the ROS induced by ionic liquids.

Microalgae have potential for environmental remediation, but they must better tolerate stress. Adaptive laboratory evolution (ALE) is effective to construct evolved strains, but its efficiency is low. Highly efficient ALE relies on selecting suitable environmental stress, original strain selection, and optimizing initial cell density and stress strategy.

Microbes have proven to be robust workhorses for the large-scale production of many chemicals. Especially, high-value biochemicals (e.g., natural pigments, unsaturated fatty acids) that cannot be derived from fossil fuels, can be produced by engineered microbes. There is a growing interest in both academia and industry to find new technologies that can enhance the efficiencies of microbial cell factories and boost the circular bioeconomy. Rapid technological innovations, such as microbial genome editing and synthetic biology, have greatly advanced the production of chemicals in engineered microbes. Nanomaterial-based technologies that exploit the unique physiochemical properties of nano-scale materials (e.g., large surface area, excellent catalytic activity, tunable optical and electrical performance) have demonstrated great potential and attracted increasing attention. There are many studies showing that nanomaterials can assist microbes in the synthesis of chemicals by providing micronutrients, inducing anti-ROS responses, promoting gas-liquid mass transfer, immobilizing microbial cells and promoting electron transfer in electrosynthesis. Furthermore, the latest studies demonstrate that nanomaterials can be used to construct photocatalyst-microbe hybrids and achieve solar driven chemical production. In this review, we comprehensively summarize these advances and discuss the current gaps as well as future perspectives. With the rapid development of synthetic biology and nanotechnology, we believe more nanomaterial-based technologies will be developed and used to improve the productivity of microbial cell factories.

The accumulation of antibiotics in wastewater leads to broad antibiotic resistance, threating human health. Microalgae have been receiving attention due to their ability to remove antibiotics from wastewater. Tigecycline (TGC) is a broad-spectrum glycylcycline antibiotic. It has not been investigated for removal by microalgae. The removal kinetics of TGC by Chlorella pyrenoidosa were evaluated under different initial dry cell densities, TGC concentrations, temperatures and light intensity conditions. Approximately 90% of TGC could be removed when the TGC concentration was 10 mg∙L

High Voltage Direct Current systems based on Voltage Source Converters (VSC-HVDC) are increasingly being considered as a viable technology with advantages, above all when using underground or submarine cables, for bulk power transmission. In order to fully understand how VSC-HVDC systems can be best used within existing power systems, it is necessary to adapt conventional tools to carry out system-wide studies including this technology. Along this line, this paper proposes a simplified algorithm to solve optimal power flows (OPFs) in hybrid VSC-based Alternating Current/Direct Current (AC/DC) grids with multi-terminal VSC-HVDC systems. The proposed algorithm makes it possible to seamlessly extend a previous large-scale AC case to which several multi-terminal VSC-HVDC systems must be added. The proposed approach combines two ideas used previously in two different modelling approaches: each VSC is modelled as two generators with a coupling constraint; and DC grids are modelled as notional AC grids, since, in per unit, the equations for the former are a particular case of the latter with resistive lines and no reactive-power injections. In the proposed approach, the hybrid VSC-based AC/DC system is transformed into an equivalent only-AC system. Therefore, the OPF solution of the AC/DC system can be found with the same tool used for the previous AC problem and a simple extension of the original case.

Microalgal lipids have drawn great attention as a promising sustainable resource for biodiesel or food supplement production. The development of high-performance strains of microalgae by metabolic engineering is invaluable for increasing the quantity or quality of desired lipids. The synthesis routes of lipids used as biodiesel in microalgae are based on fatty acid synthase (FAS) and triacylglycerols (TAG) biosynthesis pathway. Polyunsaturated fatty acids (PUFAs), including ω-6 and ω-3 fatty acids, are essential nutrients for humans. Notably, microalgae possess two distinct pathways for polyunsaturated fatty acids (PUFAs) biosynthesis, including the desaturase/elongase pathway and the polyketide synthase (PKS) pathway. Thus, it is necessary to identify which biosynthetic pathways are responsible for PUFA synthesis in particular microalgae species. In recent years, various key enzymes and functional domains involved in fatty acid and TAG biosynthesis pathway were identified and potentially regulated by genetic engineering approaches to elevate specific lipids content. In addition, other studies have reported the implementation of strategies to increase lipid accumulation based on increasing acetyl-CoA/NADPH supply, enhancing photosynthetic efficiency, or blocking competing pathways. Furthermore, other efforts have used transcription factor engineering to simultaneously regulate multiple genes related to lipid accumulation. This review summarizes recent research about a variety of microalgae lipid biosynthesis pathways, and discusses multiple gene manipulation strategies that have been employed for specific lipid overproduction in industrial microalgae.

Carbon dioxide and other greenhouse gas emissions leads to global warming. Biological capture through microalgae is a potential approach for solving this environmental problem. It is still a technical challenge to enhance the tolerance of microalgae to flue gas if CO2 is fixed from flue gas directly. A new strain, Chlorella sp. Cv was obtained through adaptive evolution (46 cycles) against simulated flue gas (10% CO2, 200 ppm NOx and 100 ppm SOx). It was confirmed that Chlorella sp. Cv could tolerate simulated flue gas conditions and the maximum CO2 fixation rate was 1.2 g L−1 d−1. In a two-stage process, the biomass concentration was 2.7 g L−1 and the carbohydrate content was 68.4%. Comparative transcriptomic analysis was performed for Chlorella sp. Cv under simulated flue gas and control conditions (10% CO2). These responses against simulated flue gas uncovered the significant difference between the evolved strain and the original strain. The metabolic responses to flue gas were explored with focus on various specific genes. Upregulation of several genes related to photosynthesis, oxidative phosphorylation, CO2 fixation, sulfur metabolism and nitrogen metabolism was beneficial for the evolved strain to tolerate the simulated flue gas. The upregulation of genes related to extracellular sulfur transport and nitrate reductase was essential to utilize the sulfate and nitrate from dissolved SOx and NOx. The results in this study are helpful to establish a new process for CO2 capture directly from industrial flue gas.

Polyunsaturated fatty acid (PUFA) synthase is a special and effective enzyme for PUFA synthesis, and dehydratase (DH) domain played a crucial role in it. In this work, we compared four different DH domains from different strains (Schizochytrium sp. HX-308 and Shewanella sp. BR-2) and different gene clusters. First bioinformatics analysis showed that DH1, 2 and DH3 were similar to FabA and PKS-DH, respectively, and all of them got a hot-dog structure. Second, four DH domains were expressed in Escherichia coli that increased biomass. Especially, Schi-DH1,2 presented the highest dry cell weight of 2.3 g/L which was 1.62 times of that of control. Fatty acids profile analysis showed that DH1,2 could enhance the percentage of unsaturated fatty acids, especially DH1,2 from Schizochytrium sp., while DH3 benefited for the saturated fatty acid biosynthesis. Furthermore, five kinds of fatty acids were added to the medium to study the substrate preferences. Results revealed that DH1,2 domain preferred to acting on C16:0, while DH3 domain trended acting on C14:0 and C15:0, which illustrated DH from different clusters do have specific substrate preference. Besides, DH expression could save the cell growth inhibition by mid-chain fatty acids. This study provided more information about the catalysis mechanism of polyunsaturated fatty acid synthase and might promote the modification study based on this enzyme.

High-voltage direct current (HVDC) systems are called to play an important role in future power systems, and therefore, transmission system operators (TSOs) are keen to explore design and analysis tools for those systems embedded in traditional high-voltage alternating current (HVAC) systems. This chapter presents the fundamentals of HVDC systems and illustrates how optimal power flow (OPF) calculations can be carried out in hybrid AC/DC systems when the two sides are interfaced through voltage source converters (VSCs), which is an arrangement with a promising future for its many advantages. Tools for OPF studies could help TSOs assess the profitability of modern high-voltage AC/DC systems at the transmission expansion planning (TEP) stage and to operate them optimally once they are installed. The OPF algorithm presented in this chapter can deal with large-scale hybrid power networks with a fairly detailed representation of the generation and transmission systems (both AC and DC) including detailed loss models. Two alternative formulations of the algorithm are described here in detail: (a) a nonlinear approach to OPF and (b) a linear one. The two alternatives are compared thoroughly in a case study. Results obtained with the nonlinear OPF model are more accurate than those obtained with the linear OPF model, but the latter presents a much lower computational burden. The linear OPF model could be useful when analyzing large-scale systems in which only active power flows are of interest.

Lipid accumulation of Schizochytrium sp. can be induced by stress condition, but this stress-induction usually reduce cell growth and cause oxidative damage, which can eventually lower the lipid yield. Here, adaptive laboratory evolution (ALE) combined high salinity was performed to enhance the antioxidant system and lipid accumulation. The final strain ALE150, which was obtained after 150 days, showed a maximal cell dry weight (CDW) of 134.5 g/L and lipid yield of 80.14 g/L, representing a 32.7 and 53.31% increase over the starting strain, respectively. Moreover, ALE150 exhibited an overall higher total antioxidant capacity (T-AOC) and lower reactive oxygen species (ROS) levels than the starting strain. Furthermore, the regulatory mechanisms responsible for the improved performance of ALE150 were analyzed by transcriptomic analysis. Genes related to the antioxidant enzymes and central carbon metabolism were up-regulation. Moreover, the metabolic fluxes towards the fatty acid synthase (FAS) and polyketide synthase (PKS) pathways were also changed.

E-voting maybe replaces the traditional voting scheme in the future, however, the security threat must be paid enough attention. In this paper, a novel e-voting scheme is proposed using secret sharing and k-anonymity, which not only satisfies the basic security goals such as the non-cheating, the universal verifiability, the confidentiality, and the anonymity, but also achieves the addition properties including coercion-resistance and unconditional security since the security of the proposed scheme does not rely on any computational hard problem.

Co-culture of microalgae and bacteria is a promising method for wastewater treatment. The suitable selection of the bacteria in co-cultures with microalgae is critical for wastewater treatment. Three bacteria, Exiguobacterium aurantiacum, Stenotrophomonas acidaminiphila, and Chryseobacterium scophthalmus, were the dominant bacterial species in fermentation wastewater treated by microalgae and activated sludge. Pure cultures and co-cultures of microalgae (Chlorella sorokiniana L3) and these bacteria were evaluated for the treatment of fermentation wastewater, which contains high concentrations of acetate acid, butyric acid, ethanol and butanol. The performance of the co-cultures was better than that of pure cultures of microalgae or bacteria for the removal of four organic compounds, and the removal efficiency of volatile fatty acids and alcohols in the best co-culture case was increased by 22.70% compared to that of pure cultures. Butanol and butyric acid were much more difficult for microalgae and bacteria to remove than were acetic acid and ethanol. The co-cultures of Chlorella sorokiniana L3 with Stenotrophomonas acidaminiphila or Chryseobacterium scophthalmus had the highest removal efficiencies for the four organic compounds in all treatments. The co-cultures of Chlorella sorokiniana L3 with Exiguobacterium aurantiacum, Stenotrophomonas acidaminiphila or Chryseobacterium scophthalmus promoted not only chlorophyll a + b production but also biomass accumulation of Chlorella sorokiniana L3 during the 3 days of cultivation compared with those in pure cultures. More than 77.8% of NH4+-N, 45.6% of total PO43−-P and 63.7% of COD (chemical oxygen demand) were removed in all co-cultures. These three bacteria are potential candidates for wastewater treatment through co-culture with microalgae.

Phenol is a typical pollutant which can be degraded by microalgae. Phenol induces formation of reactive oxygen species (ROS). Tolerance to oxidative damage produced by ROS is critical for phenol degradation by microalgae. An evolved strain, Chlorella sp. L5 was obtained from Chlorella sp. L3 in a previous study. The current study investigated the phenol tolerance mechanism by the dynamic responses of antioxidative enzyme activities of Chlorella sp. L3 and Chlorella sp. L5 in TAP medium with and without 500 mg L−1 phenol. It was shown that the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were increased in Chlorella sp. L5 when phenol was added in the medium. They were also significantly higher than those of Chlorella sp. L3 under 500 mg L−1 phenol conditions. There were slight increases of the malondialdehyde (MDA) contents of Chlorella sp. L5 in TAP medium with and without 500 mg L−1 phenol while they were significantly lower than the MDA content of Chlorella sp. L3 under 500 mg L−1 phenol conditions. The results indicated that Chlorella sp. L5 had higher tolerance to 500 mg L−1 phenol than Chlorella sp. L3. The antioxidative responses of Chlorella sp. L3 and Chlorella sp. L5 in control and TAP medium + phenol were consisted with the results of the comparative transcriptomic analysis in another published result. The phenol tolerance mechanism was also confirmed by the photosynthetic efficiency under oxidative conditions and control.

Background Schizochytrium sp. is a marine microalga with great potential as a promising sustainable source of lipids rich in docosahexaenoic acid (DHA). This organism’s lipid accumulation machinery can be induced by various stress conditions, but this stress induction usually comes at the expense of lower biomass in industrial fermentations. Moreover, oxidative damage induced by various environmental stresses can result in the peroxidation of lipids, and especially polyunsaturated fatty acids, which causes unstable DHA production, but is often ignored in fermentation processes. Therefore, it is urgent to develop new production strains that not only have a high DHA production capacity, but also possess strong antioxidant defenses. Results Adaptive laboratory evolution (ALE) is an effective method for the development of beneficial phenotypes in industrial microorganisms. Here, a novel cooperative two-factor ALE strategy based on concomitant low temperature and high salinity was applied to improve the production capacity of Schizochytrium sp. Low-temperature conditions were used to improve the DHA content, and high salinity was applied to stimulate lipid accumulation and enhance the antioxidative defense systems of Schizochytrium sp. After 30 adaptation cycles, a maximal cell dry weight of 126.4 g/L and DHA yield of 38.12 g/L were obtained in the endpoint strain ALE-TF30, which was 27.42 and 57.52% higher than parental strain, respectively. Moreover, the fact that ALE-TF30 had the lowest concentrations of reactive oxygen species and malondialdehyde among all strains indicated that lipid peroxidation was greatly suppressed by the evolutionary process. Accordingly, the ALE-TF30 strain exhibited an overall increase of gene expression levels of antioxidant enzymes and polyketide synthases compared to the parental strain. Conclusion This study provides important clues on how to overcome the negative effects of lipid peroxidation on DHA production in Schizochytrium sp. Taken together, the cooperative two-factor ALE process can not only increase the accumulation of lipids rich in DHA, but also prevent the loss of produced lipid caused by lipid peroxidation. The strategy proposed here may provide a new and alternative direction for the industrial cultivation of oil-producing microalgae.

Enhancement of stress tolerance to high concentration of salt and CO2 is beneficial for CO2 capture by microalgae. Adaptive evolution was performed for improving the tolerance of a freshwater strain, Chlorella sp. AE10, to 30 g/L salt. A resulting strain denoted as Chlorella sp. S30 was obtained after 46 cycles (138 days). The stress tolerance mechanism was analyzed by comparative transcriptomic analysis. Although the evolved strain could tolerate 30 g/L salt, high salinity caused loss to photosynthesis, oxidative phosphorylation, fatty acid biosynthesis and tyrosine metabolism. The related genes of antioxidant enzymes, CO2 fixation, amino acid biosynthesis, central carbon metabolism and ABC transporter proteins were up-regulated. Besides the up-regulation of several genes in Calvin-Benson cycle, they were also identified in C4 photosynthetic pathway and crassulacean acid metabolism pathway. They were essential for the survival and CO2 fixation of Chlorella sp. S30 under 30 g/L salt and 10% CO2.

Lutein is one of high-value added pigments from microalgae. Several energy-consuming methods for cell wall disruption have been developed due to the rigid cell wall of green algae. Ionic liquid - based approaches are considered as green technology for lutein extraction from microalgae. The structure and components of cell wall of microalgae are species specific so that it is necessary to select a suitable ionic liquid for lutein extraction. Two protocols using imidazolium-based ionic liquid from dried or fresh microalgae were evaluated for increasing the extraction efficiency of lutein from Chlorella sp. In the pretreatment process, [BMIM]Cl, [BMIM]Br, [EMIM]Cl and [EMIM]EtOSO3 were investigated. The concentration of these ionic liquids in aqueous solution, treatment temperature and time, and solid-liquid ratio (dried algae powder: ionic liquid aqueous solution) were also evaluated. The organic solvent and extraction times in lutein extraction process were also assessed. Compared with the protocol 1 (extraction from dried microalgae), extraction from fresh microalgae (protocol 2) had higher final lutein content and similar lutein extraction efficiency. Finally, the extraction efficiency was 97.73% when 10% [BMIM]Br was used to enhance cell disruption under 65 °C for 60 min for fresh microalgae. The solid-liquid ratio was 1:122. Diethyl ether was better than hexane, acetone and ethyl acetate as organic solvent. Seven times of extraction by organic solvent were enough and each time was 80 s. The current result is valuable for further development.

Improved soil carbon sink capability is important for the mitigation of carbon dioxide emissions and the enhancement of soil productivity. Biochar and organic fertilizer (OF) showed a significant improving effect on microalgae in soil carbon sink capacity, and the ultimate soil total organic carbons with microalgae-OF, microalgae-biochar, microalgae-OF-biochar were about 16, 67 and 58% higher than that with microalgae alone, respectively, indicating that carbon fixation efficiency of microalgae applied in soil was improved with biochar and OF whilst the soil carbon capacity was promoted, the mechanism of which is illustrated through simulative experiments. Organic fertilizer could spur algal conversion of carbon into cell molecules by increasing intracellular polysaccharide production of microalgae. Biochar could change carbon metabolism pathway of microalgae through altering the yield of intracellular saccharides, and yield and type of extracellular saccharides. There was a superimposition effect on the soil carbon sink when biochar and OF were both present with microalgae.

Microalgae have attracted great attention as a promising sustainable resource for biofuel production. In studies aiming to improve lipid accumulation, many key enzymes involved in lipid biosynthesis were identified and confirmed, but genetic engineering remains a challenge in most species of microalgae. In an alternative approach, various chemical modulators can be used to directly regulate the lipid biosynthesis pathway, with similar effects to gene overexpression and interference approaches, including improving the precursor supply and blocking competing pathways. The produced lipid can be protected from being converted into other metabolites by the chemicals such as lipase inhibitors. In addition, a few chemicals were also demonstrated to greatly influence cell growth and lipid accumulation by indirect regulation of the lipid biosynthesis pathway, such as increasing cell permeability or regulating oxidative stress. Thus, adding chemical modulators can be a useful alternative strategy for improving lipid accumulation in large-scale cultivation of microalgae.

Microalgae are potential candidate for biofuel production as alternative one for fossil fuels. CO2 in flue gas is available carbon source to support microalgae growth. In this study, the effects of different concentrations of the simulated flue gas onto algal growth and photosynthetic activity were evaluated for both Chlorella sp. AE10 and Chlorella sp. Cv. The growth profiles were correlated by a simple kinetic model. It was indicated that the simulated flue gas led to low pH and the photosynthetic activity was partially destroyed. Chlorella sp. Cv can tolerate full simulated flue gas, 10% CO2 + 200 ppm NOx + 100 ppm SOx . The pH in medium maintained at 6 and the photosynthetic activity was more than 0.6 at the first 6 days. If the concentration of NOx was more 100 ppm and that of SOx was more than 50 ppm, the pH was declined to 4 at day 2 or 3 for Chlorella sp. AE10. At the same time, the related photosynthetic activities of Chlorella sp. AE10 were less than 0.4, which was not suitable for algal growth. It was shown that Chlorella sp. Cv could be used for CO2 fixation from the simulated flue gas.

Temperature is an important factor that not only affects cell growth, but also changes fatty acid composition in oleaginous microorganisms. Here, adaptive laboratory evolution (ALE) was performed in Schizochytrium sp. to enhance strain thermotolerance in docosahexaeonic acid (DHA) production. The adaptive strain showed higher growth rate and lower temperature sensitivity. Cell growth rate of the adaptive strain after 70 cycles at high temperature stimulation (ALE70) at 28 °C and 34 °C were 46.93% and 60.55% higher than that of original strain. Meanwhile, the reduction ratio of DHA yield from 28 °C to 34 °C of ALE70 decreased by 61.71%. Finally, lipid and DHA concentration at 34 °C reached 4.31 and 4.33 times of the starting strain. Further physiological analysis showed ALE70 generated less ROS, synthesized less HSP proteins, and produced more pigments, which might be related to the improved performance. This work increased the fermentation temperature by 5 degrees without affecting DHA production, which significantly reduced the energy consumption cost of the industrialization.

Antibiotics are essential for treatments of bacterial infection and play important roles in the fields of aquaculture and animal husbandry. Antibiotics are accumulated in water and soil due to the excessive consumption and incomplete treatment of antibiotic wastewater. The accumulation of antibiotics in ecological systems leads to global environmental risks. The toxic effects of spiramycin (SPI), tigecycline (TGC), and amoxicillin (AMX) on Chlorella pyrenoidesa and Anabaena cylindrica were evaluated based on growth inhibition experiments, and determinations of ROS production and antioxidant enzyme activities (catalase, superoxide dismutase, and malondialdehyde). Half maximal effective concentrations (EC50) of TGC, SPI, and AMX for A. cylindrica were 62.52 μg/L, 38.40 μg/L, and 7.66 mg/L, respectively. Those were 6.20 mg/L, 4.58 mg/L, and > 2 g/L for C. pyrenoidesa, respectively. It was shown that A. cylindrica was much more sensitive to these antibiotics than C. pyrenoidesa. In addition, EC50 values of SPI and TGC were lower than that of AMX. It was indicated that SPI and TGC had higher toxic than AMX to C. pyrenoidesa and A. cylindrica. The current study is helpful to evaluating possible ecological risks of TGC, SPI, and AMX by green microalgae and cyanobacteria.

The micropayment scheme is widely used in the electronic payment, where the transaction value is tiny, meanwhile, the number of transactions is very huge. Recently, Liu and Yan proposed a lightweight micropayment scheme to achieve the efficiency, the fairness, and the privacy. However, the bank in the Liu–Yan’s scheme maybe obtain the illegal benefits by controlling the selective result. In this paper, an enhanced fairness micropayment scheme is presented to resist the attack from the malicious bank. In addition, considering that most of the users have no motivation to verify the result due to the tiny transaction value, the observers are employed to audit the process for ensuring the fairness.

Remote data integrity checking is of great importance to the security of cloud-based information systems. Previous works generally assume a trusted third party to oversee the integrity of the outsourced data, which may be invalid in practice. In this paper, we utilize the blockchain to construct a novel privacy-preserving remote data integrity checking scheme for Internet of Things (IoT) information management systems without involving trusted third parties. Our scheme leverages the Lifted EC-ElGamal cryptosystem, bilinear pairing, and blockchain to support efficient public batch signature verifications and protect the security and data privacy of the IoT systems. The results of the experiment demonstrate the efficiency of our scheme.

Eicosapentaenoic acid is one of the most important ω-3 polyunsaturated fatty acids, playing essential roles in the treatment of cardiovascular, cancer and other physiological diseases. However, fish oil-derived eicosapentaenoic acid cannot meet the growing needs, which makes the microbial production of eicosapentaenoic acid has become the current research hotspot. Some natural microorganisms including microalgae and bacteria can produce eicosapentaenoic acid but the yield cannot meet the demands. Many regulation strategies adopted to improve the amount of eicosapentaenoic acid production by process optimization and metabolic regulation. In addition, with the in-depth research on biosynthetic pathways and the rise of synthetic biology, metabolic engineering becomes a promising strategy to increase eicosapentaenoic acid production. This review will summarize the main producers of eicosapentaenoic acid and their special biosynthetic pathways, and different strategies of process engineering and metabolic engineering to improve eicosapentaenoic acid production, which might provide reference for the production of different polyunsaturated fatty acids.

Natural and human activities lead to soil degradation and soil salinization. The decrease of farmlands threatens food security. There are approximately 1 billion ha salt-affected soils all over of world, which can be made available resources after chemical, physical and biological remediation. Nostoc, Anabaena and other cyanobacterial species have outstanding capabilities, such as the ability to fix nitrogen from the air, produce an extracellular matrix and produce compatible solutes. The remediation of salt-affected soil is a complex and difficult task. During the past years, much new research has been conducted that shows that cyanobacteria are effective for salt-affected soil remediation in laboratory studies and field trials. The related mechanisms for both salt tolerance and salt-affected soil remediation were also evaluated from the perspective of biochemistry, molecular biology and systems biology. The effect of cyanobacteria on salt-affected soil is related to nitrogen fixation and other mechanisms. There are complicated interactions among cyanobacteria, bacteria, fungi and the soil. The interaction between cyanobacteria and salt-tolerant plants should be considered if the cyanobacterium is utilized to improve the soil fertility in addition to performing soil remediation. It is critical to re-establish the micro-ecology in salt-affected soils and improve the salt affected soil remediation efficiency. The first challenge is the selection of suitable cyanobacterial strain. The co-culture of cyanobacteria and bacteria is also potential approach. The cultivation of cyanobacteria on a large scale should be optimized to improve productivity and decrease cost. The development of bio-remediating agents for salt-affected soil remediation also relies on other technical problems, such as harvesting and contamination control. The application of cyanobacteria in salt-affected soil remediation will reconstruct green agriculture and promote the sustainable development of human society.

Exergy analysis is powerful tool for process optimization and mechanism analysis. In this study, exergy analysis was performed for docosahexaenoic acid (DHA) fermentation process. More than 86% of input exergy was contributed by glucose. The exergy of biomass was about 64.66% of the total output exergy when the phosphate concentration was 4 g L−1. The exergy efficiencies of DHA (ηDHA) for the starting strains and the evolved strains under high oxygen concentration, low temperature, and two-factor conditions were also investigated. The ηDHA in the collected experimental data was not more than 20.9%. It was proved that there was a positive correlation between ηDHA and the biomass yield. It was indicated that adaptive laboratory evolution (ALE) improved biomass yield which had the most important effect on enhancing ηDHA and DHA yield (or DHA productivity). It is necessary to improve ηDHA through process optimization and ALE in future.

Microalgae are arguably the most abundant single-celled eukaryotes and are widely distributed in oceans and freshwater lakes. Moreover, microalgae are widely used in biotechnology to produce bioenergy and high-value products such as polyunsaturated fatty acids (PUFAs), bioactive peptides, proteins, antioxidants and so on. In general, genetic editing techniques were adapted to increase the production of microalgal metabolites. The main genome editing tools available today include zinc finger nucleases (ZFNs), transcriptional activator-like effector nucleases (TALENs), and the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas nuclease system. Due to its high genome editing efficiency, the CRISPR/Cas system is emerging as the most important genome editing method. In this review, we summarized the available literature on the application of CRISPR/Cas in microalgal genetic engineering, including transformation methods, strategies for the expression of Cas9 and sgRNA, the CRISPR/Cas9-mediated gene knock-in/knock-out strategies, and CRISPR interference expression modification strategies.