Effect of Nitrogen Concentration on the Alkalophilic Microalga Nitzschia sp. NW129-a Promising Feedstock for the Integrated Production of Lipids and Fucoxanthin in Biorefinery

Microalgae are considered promising resources for producing a variety of high-value-added products, especially for lipids and pigments. Alkalophilic microalgae have more advantages than other microalgae when cultured outdoors on a large scale. The present study investigated the comprehensive effects of different nitrogen concentrations on fucoxanthin (Fx), lipids accumulation and the fatty acid profile of the alkaliphilic microalgae Nitzschia sp. NW129 to evaluate the potential for simultaneous production of Fx and biofuels. Fx and Lipids amassed in a coordinated growth-dependent manner in response to various concentrations, reaching 18.18 mg g–1 and 40.67% dry weight (DW), respectively. The biomass of Nitzschia sp. NW129 was 0.58 ± 0.02 g L–1 in the medium at the concentration of 117.65 mM. The highest productivities of Fx (1.44 mg L–1 d–1) and lipid (19.95 ± 1.29 mg L–1 d–1) were obtained concurrently at this concentration. Furthermore, the fatty acid methyl esters revealed excellent biofuel properties with an appropriate value of the degree unsaturation (49.97), cetane number (62.72), and cold filter plugging point (2.37), which met the European standards for biofuel production (EN14214). These results provided a reliable strategy for further industrialization and comprehensive production of biofuel and Fx by using the alkaliphilic microalgal Nitzschia sp. NW129.

Analysis of Free Sugars, Organic Acids, and Fatty Acids of Wood Apple (Limonia acidissima L.) Fruit Pulp

Wood apple (Limonia acidissima L.) is an underutilized, fruit-yielding tree that is native to India and Sri Lanka. Wood apple trees are also cultivated in India, Sri Lanka, Bangladesh, Myanmar, Thailand, Malaysia, Vietnam, Kampuchea, Laos, and Indonesia for delicious fruits and medicinal purposes. The major objective of the present work was the analysis of the nutritional status of wood apple fruit pulp.The fruits are rich in total carbohydrates (24.74 ± 0.19%), total proteins (9.30 ± 0.16%), oil (0.99 ± 0.01%), fiber (3.32 ± 0.02%), and ash (2.73 ± 0.12%). Further analysis and quantification of free sugars, organic acids, and fatty acid methyl esters were carried out by using high-performance liquid chromatography (HPLC) and gas chromatographic (GC) methods. In total, five sugars and nine organic acids were detected and quantified. The predominant sugars were fructose (16.40 ± 0.23%) and glucose (14.23 ± 0.10%), whereas the predominant organic acids were D-tartaric (4.01 ± 0.03%), ascorbic (4.51 ± 0.05%), and citric acid (4.27 ± 0.04%). The oil content of fruit pulp was 0.99 ± 0.01% and GC-MS analysis revealed that, it comprise of 16 fatty acid methyl esters. The percentage of saturated fatty acids were 32.17 ± 0.35%, that includes palmitic (18.52 ± 0.12%) and stearic acids (9.02 ± 0.08%), whereas, the unsaturated fatty acids were 51.98 ± 0.94%, including oleic acid (23.89 ± 0.06%), α-linolenic acid (16.55 ± 0.26%), linoleic acid (10.02 ± 0.43%), and vaccenic acid (1.78 ± 0.23%).

Growth and Fatty Acid Profile of the Aspergillus terreus in Different Culture Media and Temperatures

Fungi are a promising alternative source of oil to produce biodiesel, still very little known. The identification of a species with desirable characteristics is a fundamental component to achieve the economic viability of the process. The study aimed to carry out the evaluation of the fungus Aspergillus terreus in different culture media and different temperatures, the production of fungal biomass and in line with obtaining the profile of methyl esters of fatty acids. The fungal biomass revealed that in the NBRIP medium at both a temperature of 29 ºC and 36 ºC, it resulted in a great potential in the production of saturated fatty acids (SFA), which have excellent combustion properties, reaching values of 35.89 and 34,89%, respectively. For most species, the fuel would need to be mixed to make up culture conditions to be optimized and achieve the correct lipid profile, so that the fungal fuel meets European biodiesel production standards (EN 14214). Aspergillus terreus from iron ore tailings proved to be a promising microbial biomass as an energy source in the production of biodiesel.

Gamma Radiation- and Ultraviolet-Induced Polymerization of Bis(amino acid)fumaramide Gel Assemblies

Controlling the polymerization of supramolecular self-assembly through external stimuli holds great potential for the development of responsive soft materials and manipulation at the nanoscale. Vinyl esters of bis(leu or val)fumaramide (1a and 2a) have been found to be gelators of various organic solvents and were applied in this investigation of the influence of organogelators’ self-assembly on solid-state polymerization induced by gamma and ultraviolet irradiation. Here, we report our investigation into the influences of self-assemblies of bis(amino acid vinyl ester)fumaramides on gamma-ray- and ultraviolet-induced polymerization. The gelator molecules self-assembled by non-covalent interactions, mainly through hydrogen bonds between the amide group (CONH) and the carboxyl group (COO), thus forming a gel network. NMR and FTIR spectroscopy were used to investigate and characterize supramolecular gels. TEM and SEM microscopy were used to investigate the morphology of gels and polymers. Morphology studies showed that the gels contained a filamentous structure of nanometer dimensions that was exhaustive in a three-dimensional network. The prepared derivatives contained reactive alkyl groups suitable for carrying out the polymerization reaction initiated by gamma or ultraviolet radiation in the supramolecular aggregates of selected gels. It was found that the polymerization reaction occurred only in the network of the gel and was dependent on the structure of aggregates or the proximity and orientation of double bonds in the gel network. Polymers were formed by the gels exposure to gamma and ultraviolet radiation in toluene, and water/DMF gels with transcripts of their gel structure into polymers. The polymeric material was able to immobilize various solvents by swelling. Furthermore, methyl esters of bis(leu and val)fumaramide (1b and 2b) were synthesized; these compounds showed no gelling properties, and the crystal structure of the valine derivative 2b was determined.

Transformation of Triglycerides to Fatty Acid Methyl Esters with Hydrophilic Sulfonated Silica (SiO2-SO3H) as Catalyst and Quaternary Ammonium Salts in Toluene or DMSO

Triglycerides of waste cooking oil reacted with methanol in refluxing toluene to yield mixtures of diglycerides, monoglycerides and fatty acid methyl esters (FAMEs) in the presence of 20% (w/w) catalyst/oil using the hydrophilic sulfonated silica (SiO2-SO3H) catalyst alone or with the addition of 10% (w/w) co-catalyst/oil [(Bun4N)](BF4) or Aliquat 336]. The addition of the ammonium salts to the catalyst lead to a decrease in the amounts of diglycerides in the products, but the concentrations of monoglycerides increased. Mixtures of [(Bun4N)](BF4)/catalyst were superior to catalyst alone or Aliquat 336/catalyst for promoting the production of mixtures with high concentrations of FAMEs. The same experiments were repeated using DMSO as the solvent. The use of the more polar solvent resulted in excellent conversion of the triglycerides to FAME esters with all three-catalyst media. A simplified mechanism is presented to account for the experimental results.