Highest Lipid Productivity Research Articles

Non-sterile fermentation for enhanced lipid production by Cutaneotrichosporon oleaginosum using bifunctional benzamide as selective antibacterial agent and unique nitrogen source

The commercial success of micro-biodiesel is currently impeded by the high lipid production cost. Here, a novel non-sterile lipid fermentation strategy was successfully developed by using bifunctional benzamide as selective antibacterial agent and unique nitrogen source. DCW, lipid concentration, and lipid content reached 24.45 g/L, 15.85 g/L, and 64.80 % when Cutaneotrichosporon oleaginosum was cultured on 60 g/L glucose supplementing 1.5 g/L benzamide as sole nitrogen source under non-sterile condition in a 3-L bioreactor. Interestingly, the non-sterile fermentation containing high-loading of bacteria resulted in comparable lipid production with sterile fermentation. This non-sterile strategy could be expanded to inexpensive substrates including crude glycerol and cassava starch hydrolysate. The fatty acid compositions indicated lipids prepared by the non-sterile fermentation were suitable for biodiesel production. By avoiding the sterilization process, this strategy could effectively reduce energy consumption and simplify the production process, which was promising for improving the techno-economics of the lipid production technology.

In silico characterization of Rhodotorula toruloides ELO-like elongases and production of very-long-chain fatty acids by expressing Rtelo2, RtKCR, RtHCD, and RtECR through IRES-mediated bicistrons.

Rhodotorula toruloides, an oleaginous yeast known for its high lipid productivity, produces lipids with low very-long-chain fatty acid (VLCFA) content. Meanwhile, the roles of enzymes, particularly the condensing enzymes, involved in VLCFA biosynthesis in R. toruloides remained unclear. In this study, two elongases, RtELO1 and RtELO2, were identified from R. toruloides U13N3 and their tertiary structure and catalytic mechanism were investigated using molecular dynamic methods. Both enzymes exhibited typical ELO-like characteristics, with active sites located within cavities formed by seven transmembrane helixes. RtELO2 displayed higher binding affinity to acyl-CoAs compared to RtELO1, and at least seven amino acid residues, including two crucial histidines in the "HXXHH" box, were identified as important for the condensation reaction. To enhance VLCFA production, an internal ribosome entry site (IRES)-mediated bicistronic strategy was developed to integrate multiple genes into the R. toruloides genome. The efficiency of IRES-mediated translation initiation reached 85.4% of cap-dependent upstream translation, based on EGFP fluorescent intensity. Using this strategy, four genes encoding enzymes involved in the VLCFA biosynthesis cycle (Rtelo2, RtKCR, RtHCD, and RtECR) were introduced into the U13N3 genome in various combinations. The results indicated that the expression of a single elongase had a modest effect on VLCFA production, but the simultaneous expression of multiple genes resulted in cumulative effects. Notably, the transformant harboring four genes exhibited a remarkable 436.8% increase in C22 and C24 VLCFA yield compared to the original strain.

Sludge from Arapaima Gigas Culture as an Alternative Culture Medium for Lipid Production in Nannochloropsis Sp

Objective: The objective of this work was to evaluate the use of sludge generated during the culture of Arapaima gigas as an alternative medium for Nannochloropsis sp. Theoretical Framework: Microalgae are photosynthetic micro-organisms with the ability to transform organic waste or effluents into valuable biomass. They are currently of great interest for their use in the food and pharmaceutical industry. Nannochloropsis sp. is a valuable microalga due to its excellent lipid profile. Method: The sludge used was collected from A. gigas culture ponds at the CITE Acuícola Pesquero Ahuashiyacu (Tarapoto-Peru). An aqueous extract of sludge (EAL) was obtained from the sample by a thermal procedure, which was dosed into the cultures at concentrations of 100, 150 and 200 mL/L. The experimental units followed the traditional batch culture arrangement under laboratory conditions. Guillard F/2 medium was used as control treatment. The characterisation of metals in the medium was performed by coupled plasma induction (ICP) and the determination of ammonium and nitrite by colorimetric tests. In addition, population density, productivity and total lipid content were estimated. Results and Discussion: Chemical analyses revealed high concentrations of calcium, sodium, magnesium, iron, potassium, phosphorus, ammonium and nitrite (655, 648, 283, 67, 32, 17, 1.5, and 10 ppm, respectively). Likewise, the best growth (3590.00 ± 91.24 x 104 cells/mL) and productivity (0.69 ± 0.01 g/L) was obtained with 200 mL/L of EAL, presenting significant statistical differences (p < 0.05) with respect to the other treatments. In contrast, the highest lipid production (29.67 ± 1.53 %) was observed in the control treatment, far exceeding the EAL cultures; however, no significant statistical difference was observed between EAL treatments. Research Implications: These results demonstrate the feasibility of using EAL as an alternative medium for the production of Nannochloropsis sp. with a positive environmental and economic impact on the production of A. gigas. Originality/Value: The use of sludge generated in fish culture, in particular A. Gigas, has not been reported previously. In this study, we demonstrate for the first time the feasibility of using this sludge in the culture of the microalga Nannochloropsis sp. which also has a high potential for use in fish larviculture.

Growth potential, biochemical properties and nutrient removal efficiency of some freshwater microalgae and their consortia from wastewater

Impact of varying nitrate (NO3-N) and phosphate (PO4-P) concentrations and sewage water (SW) on the growth, nutrient removal, lipid accumulation, enzymatic antioxidant activity and phytochemical contents of the microalgae Scenedesmus dimorphus, Coelastrella tenuitheca, Chroococcus turgidus and Parachlorella kessleri under monoculture and their consortia have been investigated. High growth rates were observed for all the four algae in both mono and mixed culture conditions at enhanced concentrations of N (1500 mg/L NO3-N) and P (40 mg/L PO4-P). The species Scenedesmus dimorphus outperformed other microalgae growing in SW in efficiently removing nitrogen. The algal consortia of mixed species was found to be more effective in phosphorus removal. The carbohydrate and protein contents were highest in Parachlorella kessleri, about 37% and 44%, respectively, in SW cultivation. The algal consortia demonstrated highest starch content (4%) in nitrogen deprived growth medium. Highest lipid production (43%) was observed in the SW culture. The species Coelastrella tenuitheca, Chroococcus turgidus and Scenedesmus dimorphus irrespective of the growth media indicated significant accumulation of phenol, flavonoid and tannin. The DPPH, catalase and ascorbic peroxidase assay showed pronounced antioxidant activity. Nutrient (N and P) enrichment exhibited enhanced antioxidant enzymatic activity and accumulation of cell storage products.

Adaptive laboratory evolution of Lipomyces starkeyi for high production of lignin derivative alcohol and lipids with comparative untargeted metabolomics-based analysis.

Adaptive laboratory evolution (ALE) is an impactful technique for cultivating microorganisms to adapt to specific environmental circumstances or substrates through iterative growth and selection. This study utilized an adaptive laboratory evolution method on Lipomyces starkeyi for high tolerance in producing lignin derivative alcohols and lipids from syringaldehyde. Afterward, untargeted metabolomics analysis was employed to find the key metabolites that play important roles in the better performance of evolved strains compared to the wild type. Lignin, a prominent constituent of plant biomass, is a favorable source material for the manufacture of biofuel and lipids. Nevertheless, the effective transformation of chemicals produced from lignin into products with high economic worth continues to be a difficult task. In this study, we exposed L. starkeyi to a series of flask passaging experiments while applying selective pressure to facilitate its adaptation to syringaldehyde, a specific type of lignin monomeric aldehyde. Using ALE, we successfully developed a new strain, DALE-22, which can synthesize syringyl alcohol up to 18.74 mM from 22.28 mM syringaldehyde with 41.9% lipid accumulation. In addition, a comprehensive examination of untargeted metabolomics identified six specific crucial metabolites linked to the improved tolerance of the evolved strain in the utilization of syringaldehyde, including 2-aminobutyric acid, allantoin, 4-hydroxyphenethyl alcohol, 2-aminoethanol, tryptophan, and 5-aminovaleric acid. The results of our study reveal how L. starkeyi adapts to using substrates produced from lignin. These findings offer important information for developing strategies to improve the process of converting lignin into valuable products for sustainable biorefinery applications.

The evaluation of Starmerella magnoliae X3 as a biodiesel feedstock based on triacylglycerol (TAG) production, lipid productivity, and fatty acid profile under nitrogen limitation and acidic pH conditions.

The effects of four initial culture pH values (3, 4, 5, and 6) and nitrogen limitation on growth, TAG accumulation, lipid production, fatty acid profile, and estimated biodiesel quality of Starmerella magnoliae X3 were investigated. TAG and lipid levels were measured by Nile Red fluorescence and sulfo-phospho-vanilin (SPV) techniques, respectively. The results showed that a combination of nitrogen limitation and acidic pH significantly (p < 0.05) increased TAG accumulation, total lipid contents, and lipid productivity in Starmerella magnoliae X3 compared to the control group. Under nitrogen limitation, the highest TAG accumulation was achieved at initial pHs of 3 and 5 after 72h of cultivation, and the highest lipid productivity (0.306g L-1 d-1) was observed after 48h at pH 3; the major fatty acids at the four pH values were oleic acid (63.6%-64%), palmitoleic acid (11.3%-12.5%), stearic acid (9.7%-11.4%), and palmitic acid (9.4%-10%). In addition, both stresses were associated with lower iodine value and higher cetane number of the biodiesel compared to the control. These findings suggest that cultivation in a low-nitrogen medium at an initial pH of 3 or 5 holds promise in increasing TAG production in Starmerella magnoliae X3.

Effects of Temperature and Nitrogen Limitation on Growth and Lipid Production of Oleaginous Microalgae from Hot Springs

Oleaginous microalgae have gained increasing attention as an alternative feedstock for biodiesel production due to the increasing demand of fuel, climate change, and global warming. This study aimed to isolate and screen robust microalgal strains from hot springs for cultivation in subtropical and tropical areas. The newly isolated oleaginous microalgae were cultivated at 30, 35 and 40 °C. Among mesophilic and thermophilic strains tested, Chlamydomonas sp. HP59 is considered the most robust strain as it showed high cell growth in a broad range of temperatures (30 - 40 °C), with the maximum dried cell weight at 40 °C. Un-optimal temperatures for cell growth did improve lipid content by 2 - 4 folds. To increase lipid production, the 2-stage cultivation, in which nitrogen-rich was applied to promote cell growth in the 1st stage and nitrogen-limitation was applied to stimulate lipid accumulation in the 2nd stage, was performed. The high temperature combined with nitrogen-limitation did improve lipid production by all microalgae. With this strategy, Chlamydomonas sp. HP59 showed the highest dried cell weight of 4.33 g/L and lipid production of 1.72 g/L. This study has shown the potential use of the newly isolated oleaginous microalgae from hot springs to be cultivated at high temperatures and under nitrogen-limited conditions for the production of biodiesel feedstocks. HIGHLIGHTS Mesophilic and thermophilic oleaginous microalgae were isolated from hot springs. Un-optimal temperatures for cell growth did improve lipid content by 2 - 4 folds. Combined effect of high temperature and nitrogen limitation effectively increased lipid content. Two-stage cultivation gave high dried cell weight and hence overall high lipid production. GRAPHICAL ABSTRACT

Neutral lipid and chrysolaminarin metabolic pathways during nitrogen starvation and recovery in the diatom Phaeodactylum tricornutum

Oleaginous diatoms, including the marine model species Phaeodactylum tricornutum, have been identified as promising sources of compounds with a biotechnological interest including triacylglycerol and the soluble polysaccharide chrysolaminarin. These two molecules are accumulated in cells under nutrient starvation conditions, however, their consumption after nutrient replenishment lack a precise characterization. In this study, two ecotypes of P. tricornutum (Pt1 and Pt4) have been subjected to a nitrate starvation followed by a resupply to monitor their response through biochemical assays and gene expression quantification. We highlighted that both ecotypes experienced a two-step response to nitrogen resupply, with a rapid initial consumption of stored soluble carbohydrates probably allowing the restart of photosynthesis and protein synthesis, followed by a consumption of neutral lipids fueling cell division. Some genes were particularly upregulated after resupply, especially those encoding the lipases Phatr3_EG02408 and Phatr3_EG00720 and the exoglucosidase Phatr3_J43302, suggesting their role in degradation processes. Additionally, ecotype Pt4 recovered faster from stress than ecotype Pt1, possibly due to differences in specific gene regulations. Overall, these findings provide potential targets for understanding lipid and carbohydrate degradation, and for creating high-lipid producing strains.

Taxonomy and fatty acid profile of Picochlorum geojense sp. nov. (Chlorophyta, Trebouxiophyceae) from Korean coastal waters

ABSTRACT The microalgal genus known as Picochlorum, belonging to the green algae family Trebouxiophyceae, is recognized for its rapid growth and high lipid productivity. A Picochlorum strain (GJ210610) was recently established from the waters off Geoje, South Sea of Korea. Picochlorum sp. GJ210610 was a single, green ellipsoidal cell with an average size ranging from 1 to 2 µm. Its reproduction occurred through autosporulation. A phylogenetic tree based on nuclear small-subunit rDNA sequences revealed that this strain formed a unique branch, distinct from other Picochlorum species. Furthermore, the secondary structure of the ITS2 sequences was revealed for the first time within Picochlorum. The newly discovered Picochlorum sp. grew between 15°C and 25°C, with survival ceasing at 30°C. The maximum specific growth rate was measured at 0.91 d−1 at 25°C. The fatty acids of Picochlorum sp. GJ210610 were palmitic acid, oleic acid, linoleic acid, and alpha-linolenic acid. Based on morphological and phylogenetic analyses, we propose Picochlorum geojense sp. nov. (GJ210610) as a new species. The results of the present study may enhance our knowledge of the taxonomy and ecological characteristics of Picochlorum.

Assessment of Biochemical Changes of Four Aspergillus Species Grown on the Medium from Agricultural Wastes

Hazardous disposal of agricultural wastes (AW) has adverse environmental consequences, including water and air pollution and the potential for disease outbreaks. On the other hand, the utilization of AW represents a missed opportunity to harness a valuable economic resource. This study was conducted with the objective of utilizing a composite medium comprising agricultural waste to cultivate Aspergillus species and assessing its impact on the species' internal chemical composition compared to malt extract media (ME). Our findings demonstrate that the agricultural waste-based medium is abundant in essential nutrients, including soluble proteins and sugars, and is also enriched with a variety of secondary metabolites. Consequently, this Change in the growth medium induces changes in the physical characteristics of fungal biomass, such as color and texture, along with a high content of biomass proteins and secondary metabolites, including phenols, flavonoids, carotenoids, and antioxidants. The A. avenaceous gave the highest biomass (1.1412 ± 0.4 g), while the A. niger gave the highest value of proteins (16.06 ± 0.4 mg/g), phenols (33.37 ± 0.8 mg/g), flavonoids (4.84 ± 0.4 mg/g), carotenoids (1.131 ± 0.09 mg/g). A. carbonarius gave the highest value of antioxidants (IC50 = 0.28 ± 0.06 mg/mL). In contrast, using malt extract as a growth medium results in high carbohydrate and lipid production; A. flavus showed the highest value for fats (56.6 ± 0.9 mg/g), whereas A. carbonarius showed the highest value for sugars (167.1 ± 6.2 mg/g). Additionally, the malt extract medium contributed to low levels of secondary metabolites, which was offset by an increase in the protein bands of the fungal species. This research recommends the use of agricultural wastes to grow fungi species as an environmentally and economically important microbiological application.

Enhancing biomass and lipid accumulation by a novel microalga for unsterilized piggery biogas slurry remediation.

The cost and efficiency of an algal-BS treatment system are determined by the specific microalgal species and BS pretreatment method. This study examines the growth of a novel algae Chlorella sp. YSD-2 and the removal of nutrients from the BS using different pretreatment methods, including dilution ratio and sterilization. The highest biomass production (1.84 g L-1) was achieved in the 1:2 unsterilized biogas slurry, which was 2.03 times higher than that in the sterilized group, as well as higher lipid productivity (17.29 mg L-1 d-1). Nevertheless, the sterilized biogas slurry at a 1:1 dilution ratio exhibited the most notable nutrient-removal efficiency, with COD at 71.97%, TP at 91.32%, and TN at 88.80%. Additionally, the analysis of 16S rRNA sequencing revealed a significant alteration in the indigenous bacterial composition of the biogas slurry by microalgal treatment, with Proteobacteria and Cyanobacteria emerging as the predominant phyla, and unidentified_Cyanobacteria as the primary genus. These findings suggest that Chlorella sp. YSD-2 exhibits favorable tolerance and nutrient-removal capabilities in unsterilized, high-strength biogas slurry, along with high productivity of biomass and lipids. Consequently, these results offer a theoretical foundation for the development of an efficient and economically viable treatment method for algal-BS.

Effect of organic carbon sources on growth, lipid production and fatty acid profile in mixotrophic culture of Scenedesmus dimorphus (Turpin) Kützing

Due to non-renewability of fossil fuels and various environmental problems associated with their use, there is a growing interest in producing biodiesel from microalgae. Finding novel microalgal strains with desired characteristics such as rapid growth rates, high lipid productivity, and suitable fatty acid compositions is important for the production of biodiesel. Comparatively, photoautotrophic cultivation of microalgae results in low biomass yields and lipid productivities. Mixotrophic and heterotrophic cultures, in contrast, lead to higher biomass and lipid productivities but their productivities are species specific and depend a lot on the organic carbon source and culture conditions. In the present study, the potential of Scenedesmus dimorphus for biodiesel oil production under mixotrophic culture was investigated. The effects of organic carbon sources (glucose, ethanol and glycerol) on growth, biomass yields, lipid contents, lipid productivities and fatty acids compositions of Scenedesmus dimorphus in mixotrophic cultures were investigated. In comparison to photoautotrophic cultures, mixotrophic cultures produced significantly higher biomass concentration, lipid content, and lipid productivities (P≤0.05) under all the cultivation conditions investigated. The maximum biomass and lipid productivities achieved by mixotrophic culture were 83.88±0.05 and 17.11±0.04 mg L−1 day−1 respectively which are more than 2.6 and 3.1 folds higher than those obtained under photoautotrophic condition. Using glucose as the organic carbon source was better than ethanol and glycerol in terms of biomass and lipid productivities (glucose > ethanol > glycerol). The majority of the produced fatty acids were composed of C16 and C18 fatty acids. The two most abundant fatty acids in all the cultures were linolenic and palmitic acids. The values of biodiesel properties of oil obtained from S. dimorphus are within the American (ASTM D6751) and European (EN 14214) biodiesel specifications. The results show that S. dimorphus has good potentials for biodiesel oil production and that the productivity can be enhanced by mixotrophic cultivation.

Development of a CRISPR/Cas9-mediated gene-editing method to isolate a mutant of the unicellular green alga Parachlorella kessleri strain NIES-2152 with improved lipid productivity

BackgroundPreviously, we isolated a mutant of Parachlorella kessleri named strain PK4 that accumulated higher concentrations of lipids than the wild-type strain. Resequencing of the PK4 genome identified mutations in three genes which may be associated with the high-lipid phenotype. The first gene, named CDMT1, encodes a protein with a calcium-dependent membrane association domain; the second gene, named DMAN1, encodes endo-1,4-β-mannanase, while the third gene, named AATPL1, encodes a plastidic ATP/ADP antiporter-like protein.ResultsTo determine which of these mutant genes are directly responsible for the phenotype of strain PK4, we delivered Cas9-gRNA ribonucleoproteins targeting each of the three genes into the wild-type cells by electroporation and successfully disrupted these three genes separately. The lipid productivity in the disruptants of CDMT1 and DMAN1 was similar to and lower than that in the wild-type strain, while the disruptants of AATPL1 exhibited > 30% higher lipid productivity than the wild-type strain under diurnal conditions.ConclusionsWe succeeded in improving the lipid productivity of P. kessleri by CRISPR/Cas9-mediated gene disruption of AATPL1. The effective gene-editing method established in this study will be useful to improve Parachlorella strains for industrial applications.

The Potential of Lignocellulosic Biomass Hydrolysates for Microbial Oil Production Using Yeasts and Microalgae

The use of food‐based biomass and arable land for bio‐oil and biofuel production could compromise global food security. Therefore, renewable and environmentally friendly oils for biofuels from oleaginous microorganisms such as yeasts and microalgae (heterotrophic and mixotrophic) are gaining interest within the scientific community. These microorganisms have shorter cultivation times and higher lipid productivity when compared to higher plants/food crops/autotrophic microorganisms. Despite many advantages, the high carbon requirements and production cost are limiting factors that hinder their deployment at a commercial scale. Lignocellulosic waste substrates are abundant and inexpensive materials that are rich in organic carbon in the form of cellulose and hemicellulose, which release bioavailable forms of sugars upon hydrolysis. Recent studies have shown the tremendous potential of the hydrolysates of these substrates to be utilized as carbon sources for biomass production and the accumulation of lipids in oleaginous hetero‐/mixotrophic microorganisms. Therefore, this review highlights the potential use of lignocellulosic biomass as a low‐cost carbon substrate for the cultivation of hetero‐/mixotrophic microalgae and yeast for microbial oil production for commercial applications. It also examines the current status, challenges, and future prospects for the utilization of lignocellulose biomass.

Growth and Lipid Production of Marine Microalgae Tetraselmis Chuii Cultured in Different Phosphorus Concentrations

Lipid produced in the marine microalgae, Tetraselmis chuii has the potential to be processed into biofuels which can replace the use of fossil fuels that contributes to the global warming on earth. The purpose of this study was to determine the effects of phosphorus on lipid production in Tetraselmis chuii. Therefore, Tetraselmis chuii was cultured under normal concentration of phosphorus in the Conway medium. The cell was harvested on the fourth day and then transferred and cultured under different concentrations of phosphorus (10g, 15g, 20g, 25g and 30g of NaH2 PO4 .2H2 O in 1 L Conway medium). The cell density and optical density analysis of the culture were analyzed daily whereas the biomass (dry weight) analysis and lipid extractions were carried out on every alternate day. Result of the study showed that the highest lipid production in Tetraselmis chuii was achieved on day 4 in the phosphorus sufficient culture medium (25 g/L of NaH2 PO4 .2H2 O). Under the deficiency of phosphorus in the culture medium especially when the growth reached the stationary phase, more lipids accumulated in all the treatments. Therefore, our findings illustrated that phosphorus was important in regulating the growth of Tetraselmis chuii and the lipid accumulation was higher when the growth of Tetraselmis chuii was limited by the depleted phosphorus. In addition, total lipid yields also increased with the presence of excess phosphorus in the culture medium.

Role of spirulina microalgae blends in the micro gas turbine on engine performance and emission characteristics

PurposeDiesel has traditionally been considered the best-suited and most widely used fuel in various sectors, including manufacturing industries, power production, automobiles and transportation. However, with the ongoing crisis of fossil fuel inadequacy, the search for alternative fuels and their application in these sectors has become increasingly important. One particularly interesting and beneficial alternative fuel is biodiesel derived from bio sources.Design/methodology/approachIn this research, an attempt was made to use biodiesel in an unconventional micro gas turbine engine. It will remove the concentric use of diesel engines for power production by improving fuel efficiency as well as increasing the power production rate. Before the fuel is used enormously, it has to be checked in many ways such as performance, emission and combustion analysis experimentally.FindingsIn this paper, a detailed experimental study was made for the use of Spirulina microalgae biodiesel in a micro gas turbine. A small-scale setup with the primary micro gas turbine and secondary instruments such as a data acquisition system and AVL gas analyser. The reason for selecting the third-generation microalgae is due to its high lipid and biodiesel production rate. For the conduction of experimental tests, certain conditions were followed in addition that the engine rotating rpm was varied from 4,000, 5,000 and 6,000 rpm. The favourable and predicted results were obtained with the use of microalgae biodiesel.Originality/valueThe performance and combustion results were not exactly equal or greater for biodiesel blends but close to the values of pure diesel; however, the reduction in the emission of CO was at the appreciable level for the used spirulina microalgae biodiesel. The emission of nitrogen oxides and carbon dioxide was a little higher than the use of pure diesel. This experimental analysis results proved that the use of spirulina microalgae biodiesel is both economical and effective replacement for fossil fuel.

Exploring the potential of freshwater algal species for biofuel production

The present study demonstrates the potential of freshwater algal species collected from the natural habitats of Central India for biofuel production. Algal samples were collected from different waterbodies and were microscopically examined in the laboratory. Based on the morphological features using the taxonomic keys, a total of 51 algal species (18 Cyanophyta, 22 Chlorophyta, 7 Bacillariophyta, and 4 Charophyta) were identified. Among them, 18 algal species were successfully purified in the laboratory and tested for their ability to produce biomass and lipid, which are the essential criteria to be qualified as suitable feedstock for biofuel production. The data on specific growth rates suggest that Chlorella vulgaris, Scenedesmus bijugatus, and Nitzschia recta were the fastest growing species, whereas all the members of Cyanophyta showed relatively slower growth. The biomass productivity was higher in C. vulgaris, S. bijugatus, and Anabaena sp., but the lipid production was highest in C. vulgaris followed by Haematococcus sp., whereas the members of Cyanophyta showed the lowest lipid production. Furthermore, we assessed the ability of biomass and lipid production and biochemical parameters of four selected algal species, C. vulgaris, S. bijugatus, Anabaena sp., and N. recta, due to their faster growth, higher biomass and lipid production, and abundance. Based on the cluster analyses of the values of lipid and biomass production of these species against internal N:P ratio, three distinct clusters were noticed, cluster 1: near 50:1, cluster 2: between 30:35, and cluster 3 between 15:20 cellular N:P ratios. High lipid and biomass productivity were observed between the 30:35 N:P ratio. Despite the metabolic significance of N and P for algae, more research is warranted to conclude anything precisely.

Biotechnological investigation of Pediastrum boryanum and Desmodesmus subspicatus microalgae species for a potential application in bioenergy

The production of photosynthetic microalgae is a promising ecological advantage for obtaining carbon credits. This paper addresses cultivation and preparation, growth analysis, physicochemical characterization (X-ray diffraction-XRD, Fourier transform infrared-FTIR, scanning electron microscopy-SEM, and energy dispersive spectroscopy-EDS), and thermal behavior (thermogravimetry-TG, derivative thermogravimetry-DTG, and differential scanning calorimetry-DSC) of two microalgae, namely Pediastrum boryanum-PB (CH007) and Desmodesmus subspicatus-DS (AEE431E) for a potential application as an energy resource. Regarding the former, the literature reports no specific study on the species, which shows high lipid productivity and fast growth. A synthetic culture medium (Walter culture-WC) was subjected to variations in pH, luminosity, and maximum growth reached in 12 and 13 days for PB and DS, respectively. TG/DTG curves identified the main thermal degradation stages, i.e., dehydration (DS (24.68–158.68 °C) and PB (20.06–116.18 °C)), devolatilization (DS (166.34–543.00 °C) and PB (128.22–493.93 °C)), and gasification or carbonization (DS (>550 °C) and PB (>500 °C)), and DSC curves revealed two endothermic events, an exothermic one for DS, and only one endothermic event and an exothermic one for PB. XRD patterns showed a cellulose crystallinity index (CI) for DS (22.54 %) and PB (28.82 %), confirming the predominance of amorphous regions. SEM images detected external epidermis for DS and some interconnected pores for PB. The FTIR spectra identified functional groups (lipids, proteins, and carbohydrates) and CO, CO, OH, CH, and C-O-C linkages, and EDS and ICP-OES identified the main organic, inorganic, and metallic elements. The microalgae species displayed characteristics similar to those of the other biomasses in the bioenergy industry, enabling their use in thermoconversion processes for biofuel production and considering some socioenvironmental aspects.

Cultivation of Chlorella minutissima under a novel phosphate application strategy for biodiesel production: A pilot scale study

Microalgal biodiesel is considered as a carbon-neutral and renewable energy source for replacing/blending with petroleum-based diesel fuel. Selection of a microalgal species for its potential to produce biodiesel relies significantly on its acclimatization to grow in outdoor condition with high lipid productivity. The present investigation undertakes outdoor experiments in a raceway pond system involving a local isolate of green microalga, Chlorella minutissima, throughout varied seasonal changes and culture depth. The variations in climatic and cultural parameters were documented; the optimum culture depth of 30 cm was taken for further investigation. A novel cultivation approach incorporating the sequential addition of low-dose phosphate (LDSPA) projected a lipid productivity of 5.88 ton hectare−1 year−1, which was ∼40% higher than its batch culture counterpart, along with a 14-fold reduction in phosphate application. The biodiesel exhibited the dominance of saturated and monounsaturated fatty acid methyl esters, and the fuel qualities were confirmed to be within the stipulated limitations of European, American and Indian biodiesel standards, thus nominating C. minutissima as an attractive feedstock for generating high-quality biodiesel.

Biodiesel Production from the Marine Alga Nannochloropsis oceanica Grown on Yeast Wastewater and the Effect on Its Biochemical Composition and Gene Expression.

Microalgae-based biodiesel synthesis is currently not commercially viable due to the high costs of culture realizations and low lipid yields. The main objective of the current study was to determine the possibility of growing Nannochloropsis oceanica on Saccharomyces cerevisiae yeast wastewater for biodiesel generation at an economical rate. N. oceanica was grown in Guillard F/2 synthetic medium and three dilutions of yeast wastewater (1, 1.25, and 1.5%). Biodiesel properties, in addition to carbohydrate, protein, lipid, dry weight, biomass, lipid productivity, amino acids, and fatty acid methyl ester (FAMEs) content, were analyzed and the quality of the produced biodiesel is assessed. The data revealed the response of N. oceanica to nitrogen-deficiency in the three dilutions of yeast wastewater. N. oceanica in Y2 (1.25%) yeast wastewater dilution exhibited the highest total carbohydrate and lipid percentages (21.19% and 41.97%, respectively), and the highest lipid productivity (52.46 mg L-1 day -1) under nitrogen deficiency in yeast wastewater. The fatty acids profile shows that N. oceanica cultivated in Y2 (1.25%) wastewater dilution provides a significant level of TSFA (47.42%) and can be used as a feedstock for biodiesel synthesis. In addition, N. oceanica responded to nitrogen shortage in wastewater dilutions by upregulating the gene encoding delta-9 fatty acid desaturase (Δ9FAD). As a result, the oleic and palmitoleic acid levels increased in the fatty acid profile of Y2 yeast wastewater dilution, highlighting the increased activity of Δ9FAD enzyme in transforming stearic acid and palmitic acid into oleic acid and palmitoleic acid. This study proved that the Y2 (1.25%) yeast wastewater dilution can be utilized as a growth medium for improving the quantity of specific fatty acids and lipid productivity in N. oceanica that affect biodiesel quality to satisfy global biodiesel requirements.