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This paper reports the first study of phyco-remediation of cyantraniliprole, a second-generation diamide insecticide with high toxicity and persistence in aquatic environments, using the green microalga Chlamydomonas reinhardtii. Cultures of C. reinhardtii were treated with four concentrations of cyantraniliprole (0, 25, 50, and 100 ppm). The removal efficiency, antioxidant responses, and biomass composition of the microalga were measured after 1 h and one week of exposures. C. reinhardtii was able to remove cyantraniliprole from the medium by biodegradation, biotransformation, bioaccumulation, and bio-adsorption mechanisms, achieving up to 87.0% removal within 1 h and 84.5% after one week. The microalga also maintained acceptable levels of enzymatic and non-enzymatic antioxidants, indicating its tolerance to cyantraniliprole stress. Moreover, some treated cultures (especially those with 25 and 50 ppm cyantraniliprole) showed enhanced specific growth rate, and biomass productivity compared to control cultures. In addition, those with 50 and 100 ppm cyantraniliprole showed enhanced carbohydrate and lipid concentrations compared to the control cultures. These results suggest that C. reinhardtii is a promising candidate for bioremediation of cyantraniliprole-contaminated water and biofuel production.

Abstract Background Aspergillus tubingensis is a citric acid-producing fungus that can utilize sugars in hydrolysate of lignocellulosic biomass such as sugarcane bagasse and, unlike A. niger, does not produce mycotoxins. To date, no attempt has been made to model its metabolism at genome scale. Results Here, we utilized the whole-genome sequence (34.96 Mb length) and the measured biomass composition to reconstruct a genome-scale metabolic model (GSMM) of A. tubingensis DJU120 strain. The model, named iMK1652, consists of 1652 genes, 1657 metabolites and 2039 reactions distributed over four cellular compartments. The model has been extensively curated manually. This included removal of dead-end metabolites and generic reactions, addition of secondary metabolite pathways and several transporters. Several mycotoxin synthesis pathways were either absent or incomplete in the genome, providing a genomic basis for the non-toxinogenic nature of this species. The model was further refined based on the experimental phenotypic microarray (Biolog) data. The model closely captured DJU120 fermentative data on glucose, xylose, and phosphate consumption, as well as citric acid and biomass production, showing its applicability to capture citric acid fermentation of lignocellulosic biomass hydrolysate. Conclusions The model offers a framework to conduct metabolic systems biology investigations and can act as a scaffold for integrative modelling of A. tubingensis.

This paper reports the first study of phyco-remediation of cyantraniliprole, a second-generation diamide insecticide with high toxicity and persistence in aquatic environments, using the green microalga Chlamydomonas reinhardtii. Cultures of C. reinhardtii were treated with four concentrations of cyantraniliprole (0, 25, 50, and 100 ppm). The removal efficiency, antioxidant responses, and biomass composition of the microalga were measured after 1 h and one week of exposures. C. reinhardtii was able to remove cyantraniliprole from the medium by biodegradation, biotransformation, bioaccumulation, and bio-adsorption mechanisms, achieving up to 87.0% removal within 1 h and 84.5% after one week. The microalga also maintained acceptable levels of enzymatic and nonenzymatic antioxidants, indicating its tolerance to cyantraniliprole stress. Moreover, some treated cultures (especially those with 25 and 50 ppm cyantraniliprole) showed enhanced specific growth rate, and biomass productivity compared to control cultures. In addition, those with 50 and 100 ppm cyantraniliprole showed enhanced carbohydrate and lipid concentrations compared to the control cultures. These results suggest that C. reinhardtii is a promising candidate for bioremediation of cyantraniliprole-contaminated water and biofuel production. [ABSTRACT FROM AUTHOR]

The pretreatment of lignocellulosic biomass such as Miscanthus grown on marginal agricultural land is very challenging and requires severe conditions to fractionate cell wall polymers for further valorization. The current study aimed to determine organic acid-based mild conditions to pretreat contrasting lignocellulosic Miscanthus genotypes for the efficient fractionation of cell wall components, with special focus on hemicellulose extraction. In doing so, five Miscanthus genotypes were subjected to four different acid treatments (sulfuric acid, oxalic acid, malonic acid, and citric acid) in a vertical high-pressure steam sterilizer. The results demonstrated that, among the organic acids, oxalic acid was identified as the most effective pretreatment solvent for hemicellulose separation, whereas citric acid yielded the highest amount of galacturonic acid, varying from 15 to 17 mg mL−1 across genotypes. One best performing genotype was selected for the enzymatic hydrolysis. Overall, M. floridulus genotypes exhibited the optimal quality traits for efficient bioconversion with second best in terms of ethanol production potential. [ABSTRACT FROM AUTHOR]

Currently, valuable biomolecules are sustainably produced through fermentation using genetically modified microorganisms. However, this industry also generates several waste streams, such as spent yeast (SY). To close the sustainability loop in bioproduction, it is essential to define valorization strategies for such waste streams. Hence, this study aimed to investigate the compositional differences among these novel SYs, intending to pave the way for devising highly effective and beneficial valorization strategies for these streams. In this work, SYs derived from the production of beer (SBY) and six biomolecules [β-farnesene (Fene), rebaudioside M (Reb M), manool (MN), patchouli (PAT), sandalwood (SDW), and sclareol (SCL)] through fermentations driven by engineered yeasts were characterized. The results showed that SY from Fene, MN, and PAT production have similar concentrations of protein (35.9–44% dw), minerals, and amino acids, being compatible with bulking and use as nitrogen sources. Those derived from Reb M production showed significantly higher levels of lipids (21 ± 2.6% dw) compared to all the other SYs (1.7–10.8% dw), whereas the ones derived from SCL production showed significantly higher levels of inorganic matter (45%) compared with those found in the other SYs (1.2–11.3% dw). The results showed that assessing the extent of compositional variation among different SYs derived from precision fermentations represents a primary step toward developing efficient valorization or biorefining strategies. [ABSTRACT FROM AUTHOR]

Background: Aspergillus tubingensis is a citric acid-producing fungus that can utilize sugars in hydrolysate of lignocellulosic biomass such as sugarcane bagasse and, unlike A. niger, does not produce mycotoxins. To date, no attempt has been made to model its metabolism at genome scale. Results: Here, we utilized the whole-genome sequence (34.96 Mb length) and the measured biomass composition to reconstruct a genome-scale metabolic model (GSMM) of A. tubingensis DJU120 strain. The model, named iMK1652, consists of 1652 genes, 1657 metabolites and 2039 reactions distributed over four cellular compartments. The model has been extensively curated manually. This included removal of dead-end metabolites and generic reactions, addition of secondary metabolite pathways and several transporters. Several mycotoxin synthesis pathways were either absent or incomplete in the genome, providing a genomic basis for the non-toxinogenic nature of this species. The model was further refined based on the experimental phenotypic microarray (Biolog) data. The model closely captured DJU120 fermentative data on glucose, xylose, and phosphate consumption, as well as citric acid and biomass production, showing its applicability to capture citric acid fermentation of lignocellulosic biomass hydrolysate. Conclusions: The model offers a framework to conduct metabolic systems biology investigations and can act as a scaffold for integrative modelling of A. tubingensis. [ABSTRACT FROM AUTHOR]

This research addresses the urgent need for sustainable bioenergy alternatives, specifically evaluating betel nutshells as potential replacements for conventional biomass materials like coconut and palm fibers. The objective of the study was to gauge the inherent bioenergy potential of betel nutshells through an investigation of torrefaction under varying conditions, specifically temperatures ranging from 200-300 °C and residence times between 20-60 minutes in an inert environment. In this study, proximate analyses were utilized to investigate essential characteristics including moisture content, volatile matter, ash content, and fixed carbon, while a bomb calorimeter was used to determine their higher heating values. Initial results indicated that untreated betel nutshells had higher heating values and compositional similarities to coconut and palm fibers, highlighting their potential as a bioenergy source. Advanced torrefaction processes, involving increased temperatures and extended residence times, raised the fixed carbon content and reduced moisture in betel nutshells, thereby optimizing their higher heating value. This improvement is attributed to the decomposition of covalent bonds in the biomass structures, leading to the release of volatile compounds and consequent reductions in both oxygen-to-carbon and hydrogen-to-carbon ratios. Remarkably, at an operating temperature of 300 °C and a residence time of 60 minutes, torrefied betel nutshells reached a higher heating value of 25.20 MJ/kg, marking a substantial 31.39 % increase compared to untreated specimens. This study conclusively positions betel nutshells, typically considered agricultural waste, as competitive alternatives to traditional biomass resources in the biofuel industry.

This research addresses the urgent need for sustainable bioenergy alternatives, specifically evaluating betel nutshells as potential replacements for conventional biomass materials like coconut and palm fibers. The objective of the study was to gauge the inherent bioenergy potential of betel nutshells through an investigation of torrefaction under varying conditions, specifically temperatures ranging from 200-300 °C and residence times between 20-60 minutes in an inert environment. In this study, proximate analyses were utilized to investigate essential characteristics including moisture content, volatile matter, ash content, and fixed carbon, while a bomb calorimeter was used to determine their higher heating values. Initial results indicated that untreated betel nutshells had higher heating values and compositional similarities to coconut and palm fibers, highlighting their potential as a bioenergy source. Advanced torrefaction processes, involving increased temperatures and extended residence times, raised the fixed carbon content and reduced moisture in betel nutshells, thereby optimizing their higher heating value. This improvement is attributed to the decomposition of covalent bonds in the biomass structures, leading to the release of volatile compounds and consequent reductions in both oxygen-to-carbon and hydrogen-to-carbon ratios. Remarkably, at an operating temperature of 300 °C and a residence time of 60 minutes, torrefied betel nutshells reached a higher heating value of 25.20 MJ/kg, marking a substantial 31.39 % increase compared to untreated specimens. This study conclusively positions betel nutshells, typically considered agricultural waste, as competitive alternatives to traditional biomass resources in the biofuel industry. [ABSTRACT FROM AUTHOR]

The pretreatment of lignocellulosic biomass such as Miscanthus grown on marginal agricultural land is very challenging and requires severe conditions to fractionate cell wall polymers for further valorization. The current study aimed to determine organic acid-based mild conditions to pretreat contrasting lignocellulosic Miscanthus genotypes for the efficient fractionation of cell wall components, with special focus on hemicellulose extraction. In doing so, five Miscanthus genotypes were subjected to four different acid treatments (sulfuric acid, oxalic acid, malonic acid, and citric acid) in a vertical high-pressure steam sterilizer. The results demonstrated that, among the organic acids, oxalic acid was identified as the most effective pretreatment solvent for hemicellulose separation, whereas citric acid yielded the highest amount of galacturonic acid, varying from 15 to 17 mg mL−1 across genotypes. One best performing genotype was selected for the enzymatic hydrolysis. Overall, M. floridulus genotypes exhibited the optimal quality traits for efficient bioconversion with second best in terms of ethanol production potential.

The analysis of the chemical composition of biomass plays an important role in all steps of the life cycle of biomass, especially in thermal conversion processes. Electrothermal vaporization (ETV) coupled with inductively coupled plasma optical emission spectrometry (ICP-OES) is a promising approach for biomass analysis as almost no sample preparation is required, samples can be analysed quickly, and the release of elements from the sample can potentially be quantified with temperature resolution. In this work, the concentration of seven important side and trace elements is determined in beechwood, torrefied wood, wheat straw, miscanthus, and spruce bark. For comparison and validation of the ETV setup, four additional methods of analysis are applied to determine the elemental concentration. Chemical fractionation analysis (CFA) is conducted to investigate the chemical association form. In addition, microwave pressure digestion is carried out with two different acid solutions (HNO3 and HBF4). X-ray fluorescence (XRF) analysis is performed to determine the ash composition of all samples. The spread between most of the results of the different measurement techniques is with less than 20 % well within the expected range for heterogeneous biomass samples. Large deviations, such as the sulphur concentration in the XRF analysis, can be explained by the method used. The ETV results are in very good agreement with the CFA and microwave pressure digestion results. As these methods are well established, ETV analysis has proven to be suitable for the analysis of side and trace elements in biomass. [ABSTRACT FROM AUTHOR]

Photosynthesis, growth and biochemical composition of the biomass of the freshwater microalga Chlamydopodium fusiforme cultures outdoors in a thin-layer cascade were investigated. Gross oxygen production measured off-line in samples taken from the outdoor cultures was correlated with the electron transport rate estimated from chlorophyll a fluorescence measurements. According to photosynthesis measurements, a mean of 38.9 ± 10.3 mol of photons were required to release one mole of O2, which is 4.86 times higher than the theoretical value (8 photons per 1 O2). In contrast, according to the fluorescence measurements, a mean of 11.7 ± 0.74 mol of photons were required to release 1 mol of O2. These findings indicate that fluorescence-based photosynthesis rates may not be fully replace oxygen measurements to evaluate the performance of an outdoor culture. Daily gross biomass productivity was 0.3 g DW L−1 day−1 consistently for 4 days. Biomass productivity was strongly affected by the suboptimal concentration at which the culture was operated and by the respiration rate, as the substantial volume of culture was kept in the dark (about 45% of the total volume). As the cells were exposed to excessive light, the photosynthetic activity was mainly directed to the synthesis of carbohydrates in the biomass. In the morning, carbohydrate content decreased because of the dark respiration. Per contra, protein content in the biomass was lower at the end of the day and higher in the morning due to carbohydrate consumption by respiration. The data gathered in these trials are important for the future exploitation of Chlamydopodium fusiforme as a potential novel species in the field of microalgae for the production of bio-based compounds. [ABSTRACT FROM AUTHOR]

Nutrient stress as a tool for enhancement of yields and quality of biofuel products from thermal conversion processes has not received sufficient attention. Much research has been done on microalgal lipids conversion to biodiesel via the transesterification process route. However, the inefficient use of algae biomass due to the unutilized residual algal biomass and high production costs affect the economics and render the microalgal biodiesel technology less competitive to fossil-based fuels. Thermal conversion processes have gained increased attention since the processing can be applied to whole microalgae resulting in higher biofuel product yield and has the potential for producing other important products. The major challenges of thermal conversion processes of microalgae are the high level of nitrogen and oxygen content present in the product, which makes the bio-oil unstable for use as transportation fuels directly. Transportation fuels are expected to have low nitrogen content to meet environmental emission standards for combustion. Research efforts to address this challenge are ongoing, and the use of catalyst and co-thermal conversion of microalgae with other waste material has been proposed as possible options. Another promising yet to be explored approach with the thermal conversion process may involve the use of nitrogen nutrient alteration to manipulate the biomass composition to provide the requisite solution towards developing efficient and sustainable thermal conversion process for quality biofuel production from various species of microalgae. [ABSTRACT FROM AUTHOR]

Microalgal biomass is characterized by high protein, carbohydrates, and lipids concentrations. However, their qualitative and quantitative compositions depend not only on the cultivated species but also on the cultivation conditions. Focusing on the microalgae's ability to accumulate significant fatty acids (FAs) amounts, they can be valorized either as dietary supplements or for biofuel production, depending on the accumulated biomolecules. In this study, a local isolate (Nephroselmis sp.) was precultured under autotrophic conditions, while the Box–Behnken experimental design followed using the parameters of nitrogen (0–250 mg/L), salinity (30–70 ppt) and illuminance (40–260 μmol m−2 s−1) to evaluate the accumulated biomolecules, with an emphasis on the amount of FAs and its profile. Regardless of the cultivation conditions, the FAs of C14:0, C16:0, and C18:0 were found in all samples (up to 8% w/w in total), while the unsaturated C16:1 and C18:1 were also characterized by their high accumulations. Additionally, the polyunsaturated FAs, including the valuable C20:5n3 (EPA), had accumulated when the nitrogen concentration was sufficient, and the salinity levels remained low (30 ppt). Specifically, EPA approached 30% of the total FAs. Therefore, Nephroselmis sp. could be considered as an alternative EPA source compared to the already-known species used in food supplementation. [ABSTRACT FROM AUTHOR]

Digestates from different anaerobic digesters are promising substrates for microalgal culture, leading to effective wastewater treatment and the production of microalgal biomass. However, further detailed research is needed before they can be used on a large scale. The aims of this study were to investigate the culture of Chlorella sp. in DigestateM from anaerobic fermentation of brewer’s grains and brewery wastewater (BWW) and to explore the potential use of the biomass produced under different experimental conditions, including diverse cultivation modes and dilution ratios. Cultivation in DigestateM initiated from 10% (v/v) loading, with 20% BWW, obtained maximum biomass production, reaching 1.36 g L−1 that was 0.27g L−1 higher than 1.09 g L−1 of BG11. In terms of DigestateM remediation, the maximum removal of ammonia nitrogen (NH4+-N), chemical oxygen demand, total nitrogen, and total phosphorus reached 98.20%, 89.98%, 86.98%, and 71.86%, respectively. The maximum lipid, carbohydrate, and protein contents were 41.60%, 32.44%, and 27.72%, respectively. The growth of Chlorella sp. may be inhibited when the Y(II)–Fv/Fm ratio is less than 0.4.

Harvesting impacts the costs of microalgae production and affects the characteristics of the final product. Therefore, this study evaluated Moringa oleifera seed powder (MP) as a bioflocculant compared to two chemicals (Aluminium Sulphate—AS and Iron Chloride—IC) to harvest a mixed microalgae culture (Chlorella vulgaris and Desmodesmus sp.) grown on digestate. MP was the most stable flocculant but resulted in the lowest harvesting efficiency of 75%, compared to 94% for AS and 100% for IC. Process parameters such as pH, duration of mixing, grinding method for obtaining the powder, and granulometry had no significant effect on the harvesting efficiency of MP, reinforcing that this is a robust flocculant. The use of a water extraction step increased the harvesting efficiency of MP to 91%, albeit with the need for a higher dosage of flocculant. The algae harvested with MP complied with maximum tolerable levels for swine, cattle, and poultry regarding most trace elements. Nevertheless, all algae samples had Fe and Al contents above the recommended levels, possibly due to the entrapment of metal-rich digestate particles. Therefore, more attention should be paid to the final composition of algae when proposing flocculation as a harvesting method for feed production. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study firstly reported the role of DpME and nitrogen limitation in D. parva. • DpME overexpression and N stress caused increase of 27.41% in lipid content. • DpME overexpression and N stress caused increase of 26.43% in carotenoid content. • This study enhanced the application value of D. parva (an oil-producing microalga). Overexpression of Dunaliella parva (D. parva) malic enzyme (ME) gene (DpME) significantly increased DpME expression and ME enzyme activity in transgenic D. parva. Nitrogen limitation had an inhibitory effect on protein content, and DpME overexpression could improve protein content. Nitrogen limitation increased carbohydrate content, and Dunaliella parva overexpressing malic enzyme gene under nitrogen limitation (DpME-N−) group showed the lowest starch content among all groups. Dunaliella parva overexpressing malic enzyme gene under nitrogen sufficient condition (DpME) and DpME-N− groups showed considerably high mRNA levels of DpME. ME activity was significantly enhanced by DpME overexpression, and nitrogen limitation caused a smaller increase. DpME overexpression and nitrogen limitation obviously enhanced lipid accumulation, and DpME overexpression had more obvious effect. Compared with control (wild type), lipid content (68.97%) obviously increased in DpME-N− group. This study indicated that the combination of DpME overexpression and nitrogen limitation was favorable to the production of microalgae biodiesel. [ABSTRACT FROM AUTHOR]

Sorghum bicolor is a C4 grass widely cultivated for grain, forage, sugar, and biomass. The sorghum Dry Stalk (D) locus controls a qualitative difference between juicy green (dd) and dry white (D-) stalks and midribs, and co-localizes with a quantitative trait locus for sugar yield. Here, we apply fine-mapping and genome-wide association study (GWAS) to identify a candidate gene underlying D, and use nearly isogenic lines (NILs) to characterize the transcriptional, compositional, and agronomic effects of variation at the D locus. The D locus was fine-mapped to a 36 kb interval containing four genes. One of these genes is a NAC transcription factor that contains a stop codon in the NAC domain in the recessive (dd) parent. Allelic variation at D affects grain yield, sugar yield, and biomass composition in NILs. Green midrib (dd) NILs show reductions in lignin in stalk tissue and produce higher sugar and grain yields under well-watered field conditions. Increased yield potential in dd NILs is associated with increased stalk mass and moisture, higher biomass digestibility, and an extended period of grain filling. Transcriptome profiling of midrib tissue at the 4-6 leaf stages, when NILs first become phenotypically distinct, reveals that dd NILs have increased expression of a miniature zinc finger (MIF) gene. MIF genes dimerize with and suppress zinc finger homeodomain (ZF-HD) transcription factors, and a ZF-HD gene is associated with midrib color variation in a GWAS analysis across 1,694 diverse sorghum inbreds. A premature stop codon in a NAC gene is the most likely candidate polymorphism underlying the sorghum D locus. More detailed understanding of the sorghum D locus could help improve agronomic potential in cereals.

Global energy demand and fossil fuels impact on climate can be partially managed by an increase in the use of biofuels for transports and industries. Biodiesel production is generally preceded by a transesterification process of the green biomass triacylglycerols that generates large amounts of glycerol as a by-product. In this study, the extremophilic red microalga Galdieria sulphuraria 074W was cultivated in heterotrophy. The microalgal growth parameters and biomass composition were compared when grown on an equivalent molar concentration of carbon of either glucose or glycerol as unique carbon source. The maximal biomass reached in these two conditions was not significantly different (~2.5 g.L-1). Fatty acid profile, protein and storage carbohydrate contents were also statistically similar, irrespectively of the metabolized carbon source. We also observed that the pigment content of G. sulphuraria cells decreased during heterotrophic growth compared to photoautotrophic cultivated cells, and that this diminution was more important in the presence of glucose than glycerol: cells were yellowish in the presence of glucose and green in the presence of glycerol. The pigmentation was restored when glucose was totally consumed in the medium, suggesting that the presence of glucose repressed pigment synthesis. Based on this observation, a transcriptome analysis was performed in order to better understand the mechanisms involved in the loss of color mediated by darkness and by glucose in G. sulphuraria. Three conditions were analyzed: heterotrophy with glycerol or glucose and phototrophy. This allowed us to understand the transcriptional response of cells to light and dark environments both at the nuclear and chloroplast levels, and to show that transcription of gene families, acquired by horizontal gene transfer, such as sugar, amino acid, or acetate transporters, were involved in the response to the availability of different (in)organic sources. [ABSTRACT FROM AUTHOR]

To maximize food waste utilization, it is necessary to understand the effect of process variables on product distribution. To this day, there is a lack of studies evaluating the effects of the multiple variables of HTC on food waste. A Design of Experiment (DoE) approach has been used to investigate the influence of three process variables on the product distribution and composition of process streams from the HTC of food waste. This work evaluates the effect of hydrothermal carbonization process conditions on the composition and utilization capabilities of hydrochar from food waste. Parametric analysis was carried out with a design of experiments of central composite rotatable design (CCRD) and response surface methodology (RSM). Derringer's desirability function was employed to perform a multi-response evaluation. The optimized process conditions were 260.4 °C, 29.5 min reaction time, and 19.6% solid load. The predicted optimized responses were EMC = 2.7%, SY = 57.1%, EY = 84.7%, ED = 1.5, and HHV of 31.8 MJ/Kg, with a composite desirability of 0.68. Temperature and solid load had a significant effect on all evaluated responses, while reaction time was non-significant. [ABSTRACT FROM AUTHOR]

Energy consumption places growing demands on modern lifestyles, which have direct impacts on the world’s natural environment. To attain the levels of sustainability required to avoid further consequences of changes in the climate, alternatives for sustainable production not only of energy but also materials and chemicals must be pursued. In this respect, syngas fermentation has recently attracted much attention, particularly from industries responsible for high levels of greenhouse gas emissions. Syngas can be obtained by thermochemical conversion of biomass, animal waste, coal, municipal solid wastes and other carbonaceous materials, and its composition depends on biomass properties and gasification conditions. It is defined as a gaseous mixture of CO and H2 but, depending on those parameters, it can also contain CO2, CH4 and secondary components, such as tar, oxygen and nitrogenous compounds. Even so, raw syngas can be used by anaerobic bacteria to produce biofuels (ethanol, butanol, etc.) and biochemicals (acetic acid, butyric acid, etc.). This review updates recent work on the influence of biomass properties and gasification parameters on syngas composition and details the influence of these secondary components and CO/H2 molar ratio on microbial metabolism and product formation. Moreover, the main challenges, opportunities and current developments in syngas fermentation are highlighted in this review.

Global energy demand and fossil fuels impact on climate can be partially managed by an increase in the use of biofuels for transports and industries. Biodiesel production is generally preceded by a transesterification process of the green biomass triacylglycerols that generates large amounts of glycerol as a by-product. In this study, the extremophilic red microalga Galdieria sulphuraria 074W was cultivated in heterotrophy. The microalgal growth parameters and biomass composition were compared when grown on an equivalent molar concentration of carbon of either glucose or glycerol as unique carbon source. The maximal biomass reached in these two conditions was not significantly different (∼2.5 g.L–1). Fatty acid profile, protein and storage carbohydrate contents were also statistically similar, irrespectively of the metabolized carbon source. We also observed that the pigment content of G. sulphuraria cells decreased during heterotrophic growth compared to photoautotrophic cultivated cells, and that this diminution was more important in the presence of glucose than glycerol: cells were yellowish in the presence of glucose and green in the presence of glycerol. The pigmentation was restored when glucose was totally consumed in the medium, suggesting that the presence of glucose repressed pigment synthesis. Based on this observation, a transcriptome analysis was performed in order to better understand the mechanisms involved in the loss of color mediated by darkness and by glucose in G. sulphuraria. Three conditions were analyzed: heterotrophy with glycerol or glucose and phototrophy. This allowed us to understand the transcriptional response of cells to light and dark environments both at the nuclear and chloroplast levels, and to show that transcription of gene families, acquired by horizontal gene transfer, such as sugar, amino acid, or acetate transporters, were involved in the response to the availability of different (in)organic sources.

Microalgal biomass is characterized by high protein, carbohydrates, and lipids concentrations. However, their qualitative and quantitative compositions depend not only on the cultivated species but also on the cultivation conditions. Focusing on the microalgae’s ability to accumulate significant fatty acids (FAs) amounts, they can be valorized either as dietary supplements or for biofuel production, depending on the accumulated biomolecules. In this study, a local isolate (Nephroselmis sp.) was precultured under autotrophic conditions, while the Box–Behnken experimental design followed using the parameters of nitrogen (0–250 mg/L), salinity (30–70 ppt) and illuminance (40–260 μmol m−2 s−1) to evaluate the accumulated biomolecules, with an emphasis on the amount of FAs and its profile. Regardless of the cultivation conditions, the FAs of C14:0, C16:0, and C18:0 were found in all samples (up to 8% w/w in total), while the unsaturated C16:1 and C18:1 were also characterized by their high accumulations. Additionally, the polyunsaturated FAs, including the valuable C20:5n3 (EPA), had accumulated when the nitrogen concentration was sufficient, and the salinity levels remained low (30 ppt). Specifically, EPA approached 30% of the total FAs. Therefore, Nephroselmis sp. could be considered as an alternative EPA source compared to the already-known species used in food supplementation.

The environmental and social problems associated with increasing world population and industrial development have brought concerns related to water and atmospheric pollution, climate change, as well as the production of staple food. In addition, concerns about healthy food for improving life quality have also increased. In this review, microalgae composition, nutritional and functional characteristics are detailed for justifying the feasibility of employing their biomass as ingredients in staple foods for human consumption. It also contains information related to technological and sensorial properties of food containing microalgae biomass, such as meat analogue products, biscuits and cookies, pasta, soup, yogurt, bread and other staple foods. Considering not only the biochemical composition, but also the nutritional and functional features, microalgae biomass seem to be the most promising alternative for sustainable production of ingredients for healthy staple food, comprising vegetarian/vegan diets. This technology allows developing and consolidating Bioeconomy and also helps to achieve some of the U.N. Sustainable Development Goals, such as zero hunger, life on land, life below water, and also responsible consumption and production. [Display omitted] • Microalgae biomass has high levels of essential nutrients and functional compounds. • Microalgae are sustainable ingredients for high quality staple food. • Staple food enrichment is a potential efficient strategy to improve human health. • Microalgae biotechnology collaborates to circular economy and bioeconomy concepts. • Microalgae based food can help to achieve UN Sustainable Development Goals. [ABSTRACT FROM AUTHOR]

Microalgae have been recently recognized as a promising alternative for the effective treatment of anaerobic digestion effluents. However, to date, a widely applied microalgae-based process is still absent, due to several constraints mainly attributed to high ammonia concentrations and turbidity, both hindering microalgal growth. Within this scope, the purpose of the present study was to investigate the performance of two Chlorella strains, SAG 211-11b and a local Algerian isolate, under different nitrogen levels, upon ammonia stripping. The experiments were performed on cylindrical photobioreactors under controlled pH (7.8 ± 0.2) and temperature (25 ± 2 °C). Cultures were monitored for biomass production and substrate consumption. After sampling at the beginning of the stationary phase of growth (12th day) and after the maturation of the cells (24th day), an analysis of the produced biomass was conducted, in terms of its biochemical components. The local isolate grew better than C. vulgaris 211-11b, resulting in 1.43 mg L−1 biomass compared to 1.02 mg L−1 under 25 mg NH4-N L−1, while organic carbon and nutrient consumption varied between the two strains and different conditions. Concerning biomass quality, a high initial NH4-N concentration led to high protein content, while low nitrogen levels favored fatty acid (FA) accumulation, though the production of pigments was inhibited. In particular, the protein content of the final biomass was determined close to 45% of the dry weight in all experimental scenarios with adequate nitrogen, while proteins decreased, and the fatty acids approached 20% in the case of the local isolate grown on the substrate with the lowest initial ammonium nitrogen (25 mg NH4-N L−1). The novelty of the present work lies in the comparison of a microalga with industrial applications against a local isolate of the same species, which may prove to be even more robust and profitable. [ABSTRACT FROM AUTHOR]

Rhodomonas salina is a microalgal species, belonging to the cryptophytes, and is widely used as aquaculture feed because of its high nutritional profile and phycoerythrin content. This study investigated the effect of pH on the growth, biochemical composition, and taste of R. salina when cultivated on a semi-large scale under natural light conditions. Two tubular photobioreactors (200 L) were used for the cultivation of R. salina with sunlight as the only illumination source. Two different pH setpoints were applied, 7 and 8.5. Optimal temperature and nutrient conditions were applied, according to previous research findings. The results demonstrated that the productivity of R. salina was higher at pH 7, 0.06–0.14 gdry weight L−1 day−1, compared to pH 8.5, 0.03–0.12 gdry weight L−1 day−1. It was found that protein and total fatty acid concentrations were higher in the biomass that was produced at pH 8.5, 33.7% and 12.3% of dry weight, respectively, while at pH 7, the protein content was 31.9% and the total fatty acids 8.8% of dry weight. The phycoerythrin concentration, like protein, was higher at pH 8.5, 2.7% of dry weight, compared to pH 7, 1% of dry weight. The free amino acid and nucleotide profile of R. salina was affected by the pH, resulting in increased equivalent umami concentration at pH 7. For the sensory evaluation, an expert panel on algae flavors evaluated the effect of pH on the taste of R. salina, reporting that the biomass that was produced at pH 7 had more umami flavor than the biomass that was produced at pH 8.5, which was evaluated as more bitter. [ABSTRACT FROM AUTHOR]

Abstract The replacement of silage maize with giant reed as energy crop has been proposed as a mean for reducing the need of irrigation water as well as monetary and environmental costs of cultivation. Little is known about giant reed response to within‐season harvesting, and its effect on the methane production in anaerobic digestion. The effect of three harvest schedules on yield, biomass composition and methane production of giant reed was evaluated at one site of the Po Valley, northern Italy, for three consecutive years. In a completely randomized block design with four replicates the treatments applied annually were: (i) double harvest 1: first cut at the end of June + second cut at the beginning of October (DH1); (ii) double harvest 2: first cut at the end of July + second cut at the beginning of October (DH2); (iii) single harvest at the beginning of October (SH). The crop stand was established in the year 2015 and treatments were repeatedly applied in the years 2016, 2017 and 2018. The SH treatment determined the highest average annual dry matter (DM) yield (59.0 Mg DM ha−1). The DM yield for treatments with double harvest was significantly lower, that is, −30% for DH1 and −15% for DH2. In terms of specific methane yield there was little advantage in harvesting biomass twice during the growing season. The average specific methane yield varied substantially between years (i.e. from 144 to 233 ml CH4 g−1 VS), and in every year the values tended to decrease with the ageing of harvested biomass. Methane yield per hectare, however, was driven by DM yield, thus SH also determined the highest average value (9110 m3 CH4‐STP ha−1). In conclusion, the single annual harvest at the end of the growing season is an ideal strategy for maximizing methane production from giant reed.

Abstract Background Pyrolysis-molecular beam mass spectrometry (py-MBMS) analysis of a pedigree of Populus trichocarpa was performed to study the phenotypic plasticity and heritability of lignin content and lignin monomer composition. Instrumental and microspatial environmental variability were observed in the spectral features and corrected to reveal underlying genetic variance of biomass composition. Results Lignin-derived ions (including m/z 124, 154, 168, 194, 210 and others) were highly impacted by microspatial environmental variation which demonstrates phenotypic plasticity of lignin composition in Populus trichocarpa biomass. Broad-sense heritability of lignin composition after correcting for microspatial and instrumental variation was determined to be H 2 = 0.56 based on py-MBMS ions known to derive from lignin. Heritability of lignin monomeric syringyl/guaiacyl ratio (S/G) was H 2 = 0.81. Broad-sense heritability was also high (up to H 2 = 0.79) for ions derived from other components of the biomass including phenolics (e.g., salicylates) and C5 sugars (e.g., xylose). Lignin and phenolic ion abundances were primarily driven by maternal effects, and paternal effects were either similar or stronger for the most heritable carbohydrate-derived ions. Conclusions We have shown that many biopolymer-derived ions from py-MBMS show substantial phenotypic plasticity in response to microenvironmental variation in plantations. Nevertheless, broad-sense heritability for biomass composition can be quite high after correcting for spatial environmental variation. This work outlines the importance in accounting for instrumental and microspatial environmental variation in biomass composition data for applications in heritability measurements and genomic selection for breeding poplar for renewable fuels and materials.

Microalgae are valuable sources of human nutritional products, leading to growing interest in algae-based dietary supplements. Research is still ongoing for high-value commodities from microalgae to cover the food demands of the ever-increasing human population. Thus far, there is a dearth of comprehensive information available on the safety of microalgae-based products (MP) for the food sector. Algal food safety (AFS) is a nascent field, and consequently, quality analysis has not been adequately explored; the lack of hygienic requisites is a matter of concern for scientists, producers, policymakers, and consumers. In this review, we aim to provide the available knowledge on the potential hazards, critical insights into the necessity of AFS, as well as quality control (QC) and regulations. This paper briefly reviews bottlenecks at each step of the production process, from the pre-cultivation to the storage stage. Plus, quality assessment criteria are discussed, including toxicological and microbiological standards. Additionally, it describes the role of all stakeholders in the algal food industry. Finally, we discuss a few suggested solutions to address the gaps in AFS. [Display omitted] • Comprehensive information remains scarce on the safety of microalgae-based food products. • Algal food safety is a nascent field, necessitating exploration of quality analysis and hygienic requisites. • Bottlenecks exist at each production step, from pre-cultivation to storage. • Rigorous quality assessment ensures high-quality algal products. • Collaboration between stakeholders (researchers, producers, consumers, and policymakers) helps establish best guidelines. [ABSTRACT FROM AUTHOR]

Glycerol is a byproduct of biodiesel production. Purified, this compound has several applications; however, in its crude form, its commercial value is limited. An alternative use of crude glycerol is its application as an organic carbon source in microalgal cultures. This study aimed to investigate the different concentrations in crude glycerol influence productivity, biomass concentration, and biomolecules content in cultures of Spirulina sp. LEB 18. Microalga was cultured in media supplemented with different glycerol concentrations in Erlenmeyer bioreactors during 15 days. The best glycerol concentration was 2.5 g L−1, which led to the maximum biomass productivity (0.43 g L day−1). Proteins were the largest component of the biomass (75.7% w w−1, 2.5 g L−1 glycerol) and could be used to obtain high-added-value compounds. Carbohydrates ranged from 7.0 (control) to 8.9% (1.5 g L−1) w w−1. Chlorophyll was reduced up to 47% (9.14 mg g−1) in the assay using 5 g L−1 of glycerol. The lipids produced in this condition (8.3% w w−1, 2.5 g L−1 glycerol) presented interesting properties for biodiesel production because of their high content of saturated fatty acids (260.56 mg g−1, 2.5 g L−1 glycerol). Microalgae culture with crude glycerol could aggregate value to a biodiesel co-product through biocompounds production making the biofuel production process more sustainable. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the possibility of boron removal from synthetic wastewater using a vertical constructed flow (VFCW) planted with Vetiveria zizanioides. Two boron concentrations were used (15 ± 1 and 30 ± 1 mg L-1) and a hydraulic load (HL) of 191 ±10 L m-2d-1. The wastewater samples were taken and the flow rate in the inlet and outlet of the VFCW were measured. The levels of dissolved oxygen, electrical conductivity, pH and boron were determined in the wastewater. The concentrations of the essential elements and nutrients, namely total Kjeldhal nitrogen, phosphorus, calcium, magnesium, sodium and potassium in above growth biomass composition were measured. The results showed that: boron removal efficiencies depended on the boron concentration, so 60 ±3% was obtained for the 15 mg L-1 concentration and 26 ±2% for 30 mg L-1; calcium, magnesium, potassium and sodium concentrations in the vegetal biomass decreased to the boron concentration of 30 mg L-1, and boron may have interfered with Vetiveria zizanioides growth. [ABSTRACT FROM AUTHOR]

Energy consumption places growing demands on modern lifestyles, which have direct impacts on the world's natural environment. To attain the levels of sustainability required to avoid further consequences of changes in the climate, alternatives for sustainable production not only of energy but also materials and chemicals must be pursued. In this respect, syngas fermentation has recently attracted much attention, particularly from industries responsible for high levels of greenhouse gas emissions. Syngas can be obtained by thermochemical conversion of biomass, animal waste, coal, municipal solid wastes and other carbonaceous materials, and its composition depends on biomass properties and gasification conditions. It is defined as a gaseous mixture of CO and H2 but, depending on those parameters, it can also contain CO2, CH4 and secondary components, such as tar, oxygen and nitrogenous compounds. Even so, raw syngas can be used by anaerobic bacteria to produce biofuels (ethanol, butanol, etc.) and biochemicals (acetic acid, butyric acid, etc.). This review updates recent work on the influence of biomass properties and gasification parameters on syngas composition and details the influence of these secondary components and CO/H2 molar ratio on microbial metabolism and product formation. Moreover, the main challenges, opportunities and current developments in syngas fermentation are highlighted in this review. [ABSTRACT FROM AUTHOR]

Harvesting impacts the costs of microalgae production and affects the characteristics of the final product. Therefore, this study evaluated Moringa oleifera seed powder (MP) as a bioflocculant compared to two chemicals (Aluminium Sulphate—AS and Iron Chloride—IC) to harvest a mixed microalgae culture (Chlorella vulgaris and Desmodesmus sp.) grown on digestate. MP was the most stable flocculant but resulted in the lowest harvesting efficiency of 75%, compared to 94% for AS and 100% for IC. Process parameters such as pH, duration of mixing, grinding method for obtaining the powder, and granulometry had no significant effect on the harvesting efficiency of MP, reinforcing that this is a robust flocculant. The use of a water extraction step increased the harvesting efficiency of MP to 91%, albeit with the need for a higher dosage of flocculant. The algae harvested with MP complied with maximum tolerable levels for swine, cattle, and poultry regarding most trace elements. Nevertheless, all algae samples had Fe and Al contents above the recommended levels, possibly due to the entrapment of metal-rich digestate particles. Therefore, more attention should be paid to the final composition of algae when proposing flocculation as a harvesting method for feed production.

The rapid growth of aquaculture and the lack of fish meal demand new sustainable ingredients. Although fungal biomass is found to be a promising sustainable fish feed supplementation candidate, the characteristics of this protein-rich source are closely influenced by the quality of the applied growth medium. In this work, the nutritional properties of pure filamentous fungal biomass provided from the cultivation of Aspergillus oryzae, Neurospora intermedia and Rhzopus oryzae were evaluated to assess their potential as alternative novel protein sources in fish feed. In this regard, fungal biomass yields of up to 0.19 ± 0.005 (g dry biomass/g substrate glucose) were obtained during submerged cultivation of fungal strains. The pure fungal biomass acquired could contain significant amounts of protein up to 62.2 ± 1.2% (w/w). The obtained protein had a high quality with notable inclusion of essential amino acids such as lysine, arginine, methionine and threonine with comparable concentrations to those of fish meal. Fungal biomass is mainly considered as protein source, however, entitlement of 6.9 ± 0.5, 4.0 ± 0.7 and 17.2 ± 1.1% (w/w) of lipids and ratio of polyunsaturated fatty acids (PUFA) to saturated fatty acids (SFA) of 1.37:1, 1.74:1 and 1.47:1 in A. oryzae, N. intermedia and R. oryzae, respectively, signal health benefits for the fish. Considering the results, protein-rich pure fungal biomass with amino acid composition is greatly compatible with fish meal, and contains essential nutrients such as fatty acids and minerals. This pure biomass constitutes a promising sustainable alternative supplement to be introduced in fish feed industry. [ABSTRACT FROM AUTHOR]

Introduction. The lignocellulosic biomass that comes from agricultural residues, crops dedicated to wood energy, lignocellulosic biological residues as food by-products, kitchen scraps from homes, restaurants, and commercial premises, as well as cultivated algae, can be considered raw materials for the development of the bioeconomy. Since its composition is mainly based on cellulose, hemicellulose, and lignin; they can be used to produce various value-added products from bio-construction blocks in integrated bio-refinery processes. Objective. To stablish the importance of using biomass as a raw material for its incorporation in circular economy models in biorefinery processes, such as considerations of biomass management and pretreatment of biomass, the intrinsic potential for obtaining substances of commercial value depending on the carbon chain. Development. Approximately 90 % of lignocellulosic dry matter consists of cellulose (30-60 %), hemicellulose (20-40 %), and lignin (10-25 %) interrelated in a heteromatrix, while the remainder consists of ash and extracts. It is estimated that the biomass-based power generation potential in Costa Rica ranges close to 600 MW and active projects that generate about 122 MW have been identified. Conclusion. The use of biomass is an important element to be incorporated into the production of bioenergy and the development of a renewable chemical industry that leads to the achievement of objectives framed in the development of a bio-economic model, where Costa Rica has begun its parallel incursion to the advance of the 21st century.

Herein, near infrared (NIR) spectroscopy, rapid, accurate, and non-destructive method, was employed to analyze biomass composition. Calibration and prediction models for various types of biomass were developed from NIR data by applying the partial least squares method. Cellulose, hemicellulose, and lignin in a total of 75 samples were analyzed by a wet chemical method and NIR spectroscopy. The NIR model developed for hardwood accurately predicted the lignin content with a particle size of 20–80 mesh with a correlation coefficient (R2) of >0.95, low root mean square error (0.68), high ratio of error range (22.23), and high residual predictive deviation (6.07). On the other hand, the models for other compositions exhibited relatively low prediction accuracy. Different biomass particle sizes (20–80 mesh, >40 mesh, and <40 mesh) led to statistically significant differences in NIR spectra based on the root mean square value. Although preprocessing (via smoothing, first and second derivatives) was performed to improve the prediction accuracy and reduce differences based on biomass particle size, a significant improvement was not achieved. • Raw material and pretreated biomass were used for model development based on NIR-PLS. • The model for the analysis of hardwood lignin showed excellent performance for research quantification. • The models for other compositions showed relatively low prediction accuracy. • The model development for chemical composition analysis was affected by particle size. [ABSTRACT FROM AUTHOR]

To address major knowledge gaps and barriers to the commercial development of algal biomass for biofuels and co-products, a collaborative consortium, Development of Integrated Screening, Cultivar Optimization, and Verification Research (DISCOVR) , was established in 2016. Funded by the U.S. Department of Energy (DOE) Bioenergy Technologies Office (BETO), this consortium constitutes a partnership between four DOE national laboratories - Pacific Northwest National Laboratory (PNNL), Los Alamos National Laboratory (LANL), the National Renewable Energy Laboratory (NREL), and Sandia National Laboratories (SNL) - and the Arizona Center for Algae Technology and Innovation (AzCATI) at Arizona State University. To address the barriers of strain selection for achieving high seasonal productivities with a suitable composition and culture resilience, a tiered strain down-selection pipeline is implemented. At Tier I, the temperature and salinity tolerance of strains is determined in flask cultures; at Tier II, the areal biomass productivity and composition is determined in climate-simulation photobioreactors; at Tier III, the productivity and culture stability are determined in outdoor raceways. The top performing strains move forward to long-term testing at the algae testbed site at AzCATI to generate annual biomass productivity data. Concurrent to the strain down-selection in the DISCOVR pipeline, hypotheses for increasing biomass productivity, shifting biomass composition to enhance intrinsic value, and improving culture stability and resistance to pests are also tested. Techno-economic analyses are carried out to determine whether promising findings from laboratory studies or proposed modifications in outdoor pond cultivation conditions translate into reductions in the minimum biomass selling price (MBSP). In the three years following the launch of DISCOVR, annual biomass productivity has increased from 11.7 to 17.6 g m−2 day−1, resulting in an MBSP decrease from 824 to 611 $ ton−1. • The research goal of the DISCOVR consortium is to reduce microalgae biofuels cost. • The approach is to improve biomass productivity, value, and culture stability. • The annual biomass productivity increased from 11.7 to 17.6 g m−2 day−1 in 3 years. • The resulting decrease in minimum biomass selling price was from 824 to 611 $ ton−1. [ABSTRACT FROM AUTHOR]

• Hydro-deoxynation of pyrolytic oil has been reviewed. • Bio-oil stability parameters are studied and discussed in-depth. • Techn-economic analysis (TEA) of Hydro-deoxynation of pyrolytic oil is reviewed. • The influence of reactors types on HDO of pyroltic oil is also discussed. • HDO of pyrolysis oil is a feasible technology from the economic point of view. The rapid depletion of fossil fuels and environmental concerns have led researchers to explore alternative sources of energy. Pyrolytic oil derived from biomass is considered to be a potential alternative to fossil fuels, but it lacks certain physicochemical properties that make it unsuitable to be used as fuel. For instance, the high oxygen content in the pyrolytic oil exhibits chemical instability, the tendency to polymerize, and low energy density compared to traditional fuels. The hydrodeoxygenation (HDO) method is a viable technique to enhance the desirable characteristics of pyrolytic oil for commercial applications. This method has the disadvantage of catalyst deactivation owed due to coking, and its extent depends on the nature of oxy-compounds, catalyst type, and experimental conditions. However, by varying the experimental parameters such as catalyst acidity, temperature, pressure, solvent, and reaction time, the HDO product characteristics may be tailored to meet the specific requirements and applications. In this work, we have presented a comprehensive review of multiple alternatives to produce pyrolytic oil with essential fuel characteristics. The techno-economic analysis (TEA) and kinetic analysis of the pyrolytic oil were also elaborated. Overall, the review paper highlights the influence of process variables, kinetics investigation, reactor types and techno-economic analysis of HDO. [ABSTRACT FROM AUTHOR]

Microalgae are compelling renewable resources with applications including biofuels, bioplastics, nutrient supplements, and cosmetic products. Picochlorum celeri is an alga with high industrial interest due to exemplary outdoor areal biomass productivities in seawater. Detailed proximate analysis is needed in multiple environmental conditions to understand the dynamic biomass compositions of P. celeri , and how these compositions might be leveraged in biotechnological applications. In this study, biomass characterization of P. celeri was performed under nutrient-replete, nitrogen-restricted, and hyper-saline conditions. Nutrient-replete cultivation of P. celeri resulted in protein-rich biomass (∼50% ash-free dry weight) with smaller carbohydrate (∼12% ash-free dry weight) and lipid (∼11% ash-free dry weight) partitions. Gradual nitrogen depletion elicited a shift from proteins to carbohydrates (∼50% ash-free dry weight, day 3) as cells transitioned into the production of storage metabolites. Importantly, dilutions in nitrogen-restricted 40 parts per million (1.43 mM nitrogen) media generated high-carbohydrate (∼50% ash-free dry weight) biomass without substantially compromising biomass productivity (36 g ash-free dry weight m−2 day−1) despite decreased chlorophyll (∼2% ash-free dry weight) content. This strategy for increasing carbohydrate content allowed for the targeted production of polysaccharides, which could potentially be utilized to produce fuels, oligosaccharides, and bioplastics. Cultivation at 2X sea salts resulted in a shift towards carbohydrates from protein, with significantly increased levels of the amino acid proline, which putatively acts as an osmolyte. A detailed understanding of the biomass composition of P. celeri in nutrient-replete, nitrogen-restricted, and hyper saline conditions informs how this strain can be useful in the production of biotechnological products. [Display omitted] • Picochlorum celeri TG2 is an alga with exemplary biomass productivities in seawater. • Replete P. celeri biomass was protein-rich, with fewer carbohydrates and lipids. • Gradual nitrogen starvation shifted composition to the storage metabolite starch. • High productivity and carbohydrate content obtained via daily 40 ppm N dilutions. • Hypersaline cultivation increased proline, which putatively acts as an osmolyte. [ABSTRACT FROM AUTHOR]

Microalgae have been recently recognized as a promising alternative for the effective treatment of anaerobic digestion effluents. However, to date, a widely applied microalgae-based process is still absent, due to several constraints mainly attributed to high ammonia concentrations and turbidity, both hindering microalgal growth. Within this scope, the purpose of the present study was to investigate the performance of two Chlorella strains, SAG 211-11b and a local Algerian isolate, under different nitrogen levels, upon ammonia stripping. The experiments were performed on cylindrical photobioreactors under controlled pH (7.8 ± 0.2) and temperature (25 ± 2 °C). Cultures were monitored for biomass production and substrate consumption. After sampling at the beginning of the stationary phase of growth (12th day) and after the maturation of the cells (24th day), an analysis of the produced biomass was conducted, in terms of its biochemical components. The local isolate grew better than C. vulgaris 211-11b, resulting in 1.43 mg L−1 biomass compared to 1.02 mg L−1 under 25 mg NH4-N L−1, while organic carbon and nutrient consumption varied between the two strains and different conditions. Concerning biomass quality, a high initial NH4-N concentration led to high protein content, while low nitrogen levels favored fatty acid (FA) accumulation, though the production of pigments was inhibited. In particular, the protein content of the final biomass was determined close to 45% of the dry weight in all experimental scenarios with adequate nitrogen, while proteins decreased, and the fatty acids approached 20% in the case of the local isolate grown on the substrate with the lowest initial ammonium nitrogen (25 mg NH4-N L−1). The novelty of the present work lies in the comparison of a microalga with industrial applications against a local isolate of the same species, which may prove to be even more robust and profitable.

The cryptophyte Rhodomonas sp. is a potential feed source for aquaculture live feed and resource for phycoerythrin (PE) production. This research investigates the influence of light, both quality and quantity, on the biomass productivity, composition and growth rate of Rhodomonas sp. The incident light intensity used in the experiments was 50 μmolphotons m−2 s−1, irrespective of the colour of the light, and cultivation took place in lab-scale flat-panel photobioreactors in turbidostat mode. The highest productivity in volumetric biomass (0.20 gdry weight L−1 day−1), measured under continuous illumination, was observed under green light conditions. Blue and red light illumination resulted in lower productivities, 0.11 gdry weight L−1 day−1 and 0.02 g L−1 day−1 respectively. The differences in production are ascribed to increased absorption of green and blue wavelength by phycoerythrin, chlorophyll and carotenoids, causing higher photosynthetically usable radiation (PUR) from equal photosynthetically absorbed irradiance (PAR). Moreover, phycoerythrin concentration (281.16 mg gDW−1) was stimulated under red light illumination. Because photosystem II (PSII) absorbs poorly red light, the algae had to induce more pigments in order to negate the lower absorption per unit pigment of the incident available photons. The results of this study indicate that green light can be used in the initial growth of Rhodomonas sp. to produce more biomass and, at a later stage, red light could be implemented to stimulate the synthesis of PE. Fourier-transform infrared spectroscopy (FTIR) analysis demonstrated a significant difference between the cells under different light quality, with higher contents of proteins for samples of Rhodomonas sp. cultivated under green light conditions. In comparison, higher carbohydrate contents were observed for cells that were grown under red and blue light. [ABSTRACT FROM AUTHOR]

Background: Pyrolysis-molecular beam mass spectrometry (py-MBMS) analysis of a pedigree of Populus trichocarpa was performed to study the phenotypic plasticity and heritability of lignin content and lignin monomer composition. Instrumental and microspatial environmental variability were observed in the spectral features and corrected to reveal underlying genetic variance of biomass composition. Results: Lignin-derived ions (including m/z 124, 154, 168, 194, 210 and others) were highly impacted by microspatial environmental variation which demonstrates phenotypic plasticity of lignin composition in Populus trichocarpa biomass. Broad-sense heritability of lignin composition after correcting for microspatial and instrumental variation was determined to be H2 = 0.56 based on py-MBMS ions known to derive from lignin. Heritability of lignin monomeric syringyl/guaiacyl ratio (S/G) was H2 = 0.81. Broad-sense heritability was also high (up to H2 = 0.79) for ions derived from other components of the biomass including phenolics (e.g., salicylates) and C5 sugars (e.g., xylose). Lignin and phenolic ion abundances were primarily driven by maternal effects, and paternal effects were either similar or stronger for the most heritable carbohydrate-derived ions. Conclusions: We have shown that many biopolymer-derived ions from py-MBMS show substantial phenotypic plasticity in response to microenvironmental variation in plantations. Nevertheless, broad-sense heritability for biomass composition can be quite high after correcting for spatial environmental variation. This work outlines the importance in accounting for instrumental and microspatial environmental variation in biomass composition data for applications in heritability measurements and genomic selection for breeding poplar for renewable fuels and materials. [ABSTRACT FROM AUTHOR]

The rapid development of large-scale aquaculture leads to wastewater accumulation, increasing environmental problems. Microalga cultivation is a potential biotechnological alternative to treat aquaculture wastewater. While this microorganism consumes the wastewater nutrients, high added value biomass is produced. The role of Spirulina in aquaculture wastewater treatment is not fully elucidated in the literature. Thus, this study aimed to reuse and treat aquaculture wastewater by Spirulina sp. LEB 18 cultures. The microalga growth parameters, the biochemical composition of the biomass produced, and the Spirulina efficiency to nutrient removal from the aquaculture wastewater were evaluated. The assays were performed in closed photobioreactors (1 L) using 100% aquaculture wastewater (T-0) supplemented with 25 (T-25), 50 (T-50), and 75% (T-75) of the Zarrouk synthetic culture medium. The maximum biomass concentrations showed no statistical difference between the assays T-50 (1.02 g L−1), T-25 (1.10 g L−1), and control (1.05 g L−1). The biomass from the T-25 assay showed the highest concentrations of protein (65.73%), phycocyanin (16.60 mg/mL), polyunsaturated fatty acid (38.20%), and γ-linolênico (23.29%). Besides that, the Spirulina sp. LEB 18 highest removal rate of sulfate (94.01%), phosphate (93.84%), bromine (96.77%), and COD (90.00%) was obtained from the T-25 assay. The biomass from T-25 and T-50 assays showed ideal properties for biodiesel application. The Spirulina sp. LEB 18 cultures using 100% aquaculture wastewater supplemented with 25% of Zarrouk culture medium was the best option for the aquaculture wastewater treatment, producing added value biomass and reducing production cost. [ABSTRACT FROM AUTHOR]

The replacement of silage maize with giant reed as energy crop has been proposed as a mean for reducing the need of irrigation water as well as monetary and environmental costs of cultivation. Little is known about giant reed response to within‐season harvesting, and its effect on the methane production in anaerobic digestion. The effect of three harvest schedules on yield, biomass composition and methane production of giant reed was evaluated at one site of the Po Valley, northern Italy, for three consecutive years. In a completely randomized block design with four replicates the treatments applied annually were: (i) double harvest 1: first cut at the end of June + second cut at the beginning of October (DH1); (ii) double harvest 2: first cut at the end of July + second cut at the beginning of October (DH2); (iii) single harvest at the beginning of October (SH). The crop stand was established in the year 2015 and treatments were repeatedly applied in the years 2016, 2017 and 2018. The SH treatment determined the highest average annual dry matter (DM) yield (59.0 Mg DM ha−1). The DM yield for treatments with double harvest was significantly lower, that is, −30% for DH1 and −15% for DH2. In terms of specific methane yield there was little advantage in harvesting biomass twice during the growing season. The average specific methane yield varied substantially between years (i.e. from 144 to 233 ml CH4 g−1 VS), and in every year the values tended to decrease with the ageing of harvested biomass. Methane yield per hectare, however, was driven by DM yield, thus SH also determined the highest average value (9110 m3 CH4‐STP ha−1). In conclusion, the single annual harvest at the end of the growing season is an ideal strategy for maximizing methane production from giant reed. [ABSTRACT FROM AUTHOR]

Marine microalgae and cyanobacteria are sources of diverse bioactive compounds with potential biotechnological applications in food, feed, nutraceutical, pharmaceutical, cosmetic and biofuel industries. In this study, five microalgae, Nitzschia sp. S5, Nanofrustulum shiloi D1, Picochlorum sp. D3, Tetraselmis sp. Z3 and Tetraselmis sp. C6, and the cyanobacterium Euhalothece sp. C1 were isolated from the Adriatic Sea and characterized regarding their growth kinetics, biomass composition and specific products content (fatty acids, pigments, antioxidants, neutral and polar lipids). The strain Picochlorum sp. D3, showing the highest specific growth rate (0.009 h−1), had biomass productivity of 33.98 ± 0.02 mg L−1 day−1. Proteins were the most abundant macromolecule in the biomass (32.83–57.94%, g g−1). Nanofrustulum shiloi D1 contained significant amounts of neutral lipids (68.36%), while the biomass of Picochlorum sp. D3, Tetraselmis sp. Z3, Tetraselmis sp. C6 and Euhalothece sp. C1 was rich in glycolipids and phospholipids (75%). The lipids of all studied microalgae predominantly contained unsaturated fatty acids. Carotenoids were the most abundant pigments with the highest content of lutein and neoxanthin in representatives of Chlorophyta and fucoxanthin in strains belonging to the Bacillariophyta. All microalgal extracts showed antioxidant activity and antimicrobial activity against Gram-negative E. coli and S. typhimurium and Gram-positive S. aureus.

Filamentous green algae Cladophora spp. are cosmopolitans inhabiting waters with different salinity, from freshwater to hypersaline. Eutrophication of marine and inland waters results in the huge development of filamentous green algae, which reach high biomass and occupy large areas in different water bodies. This leads to the strong negative effect on the species richness of communities, significantly reduces the aesthetic value of coastal waters, hampers the recreational use of beaches and the coastline, and complicates industrial water intake and coastal fishing. Harvesting and the use of Cladophora biomass can be an effective tool to remediate eutrophic waters. Cladophora spp. are also among the most promising subjects to use in the development of integrated multi‐trophic aquaculture; there is a big potential to use it. Aquaculture is one of the potential uses. To plan the use of a resource, business needs to know the availability and quantity of the resource, the price of the resource, as well as for what benefit and how it can be used. This review summarizes and analyses existing data to answer these questions. Cladophora biomass can be used for food for humans, livestock, cultivated fish and shrimps, as fertilizers, in the energy sector (biogas and biodiesel), and different industries. The use of Cladophora in medicine and pharmacology is one of the most profitable promising ways to utilize the biomass. This review shows that Cladophora biomass is an unlimited, low cost and valuable resource for medicine and pharmacology. [ABSTRACT FROM AUTHOR]

Abstract Background Due to its high stress tolerance and low acetate secretion, Escherichia coli W is reported to be a good production host for several metabolites and recombinant proteins. However, simultaneous co-utilization of glucose and other substrates such as acetate remains a challenge. The activity of acetyl-CoA-synthetase, one of the key enzymes involved in acetate assimilation is tightly regulated on a transcriptional and post-translational level. The aim of this study was to engineer E. coli W for overexpression of an acetylation insensitive acetyl-CoA-synthetase and to characterize this strain in batch and continuous cultures using glucose, acetate and during co-utilization of both substrates. Results Escherichia coli W engineered to overexpress an acetylation-insensitive acetyl-CoA synthetase showed a 2.7-fold increase in acetate uptake in a batch process containing glucose and high concentrations of acetate compared to a control strain, indicating more efficient co-consumption of glucose and acetate. When acetate was used as the carbon source, batch duration could significantly be decreased in the overexpression strain, possibly due to alleviation of acetate toxicity. Chemostat cultivations with different dilution rates using glucose revealed only minor differences between the overexpression and control strain. Accelerostat cultivations using dilution rates between 0.20 and 0.70 h−1 indicated that E. coli W is naturally capable of efficiently co-utilizing glucose and acetate over a broad range of specific growth rates. Expression of acetyl-CoA synthetase resulted in acetate and glucose accumulation at lower dilution rates compared to the control strain. This observation can possibly be attributed to a higher ratio between acs and pta-ackA in the overexpression strain as revealed by gene expression analysis. This would result in enhanced energy dissipation caused by an imbalance in the Pta-AckA-Acs cycle. Furthermore, yjcH and actP, genes co-transcribed with acetyl-CoA synthetase showed significant down-regulation at elevated dilution rates. Conclusions Escherichia coli W expressing an acetylation-insensitive acetyl-CoA synthetase was shown to be a promising candidate for mixed feed processes using glucose and acetate. Comparison between batch and continuous cultures revealed distinct differences in glucose-acetate co-utilization behavior, requiring additional investigations such as multi-omics analysis and further engineering towards even more efficient co-utilization strains of E. coli W.

Fleshy fruits are very varied, whether in terms of their composition, physiology, or rate and duration of growth. To understand the mechanisms that link metabolism to phenotypes, which would help the targeting of breeding strategies, we compared eight fleshy fruit species during development and ripening. Three herbaceous (eggplant, pepper, and cucumber), three tree (apple, peach, and clementine) and two vine (kiwifruit and grape) species were selected for their diversity. Fruit fresh weight and biomass composition, including the major soluble and insoluble components, were determined throughout fruit development and ripening. Best-fitting models of fruit weight were used to estimate relative growth rate (RGR), which was significantly correlated with several biomass components, especially protein content (R =84), stearate (R =0.72), palmitate (R =0.72), and lignocerate (R =0.68). The strong link between biomass composition and RGR was further evidenced by generalized linear models that predicted RGR with R -values exceeding 0.9. Comparison of the fruit also showed that climacteric fruit (apple, peach, kiwifruit) contained more non-cellulosic cell-wall glucose and fucose, and more starch, than non-climacteric fruit. The rate of starch net accumulation was also higher in climacteric fruit. These results suggest that the way biomass is constructed has a major influence on performance, especially growth rate. [ABSTRACT FROM AUTHOR]