Microorganisms are known to be natural oil producers in their cellular compartments. Microorganisms that accumulate more than 20%
of lipids on a cell dry weight basis are considered as oleaginous ...microorganisms. These are capable of synthesizing vast majority of fatty acids from short hydrocarbonated chain (C6) to long hydrocarbonated chain (C36), which may be saturated (SFA), monounsaturated (MUFA), or polyunsaturated fatty acids (PUFA), depending on the presence and number of double bonds in hydrocarbonated chains. Depending on the fatty acid profile, the oils obtained from oleaginous microorganisms are utilized as feedstock for either biodiesel production or as nutraceuticals. Mainly microalgae, bacteria, and yeasts are involved in the production of biodiesel, whereas thraustochytrids, fungi, and some of the microalgae are well known to be producers of very long-chain PUFA (omega-3 fatty acids). In this review article, the type of oleaginous microorganisms and their expertise in the field of biodiesel or omega-3 fatty acids, advances in metabolic engineering tools for enhanced lipid accumulation, upstream and downstream processing of lipids, including purification of biodiesel and concentration of omega-3 fatty acids are reviewed.
Nowadays, mushroom bioactive compounds production by submerged cultivation has attracted great interest. Controlling culture conditions in bioreactors makes submerged cultivation more reliable than ...fruiting body one. Recent research has shown that many edible mushroom strains could be cultivated in submerged liquid culture producing high biomass content and a variety of bioactive compounds such as proteins, enzymes, lipids, and carbohydrates in a safe way for using them in the food industry. Focusing on the last 5 year-research, in this review, a detailed description of submerged cultivation processes used will be presented, while different bioactive compounds derived from edible mushrooms will be recorded. Moreover, the use of bioreactors and the application of different culture conditions like temperature, pH, dissolved oxygen, inoculum, and agitation in a scale-up process, leading to the exploitation of mushrooms mycelia as vegan protein sources, nutraceuticals, food supplements, and food flavor agents by the food industry, will be highlighted and discussed. The ability to enhance the concentration of amino acids responsible for umami taste or estimate the desired concentration of substances that cause inedibility could lead to safe and high-quality biomass and bioactive compounds. This would impel FDA and EFSA to approve more food products related to mushrooms, which is of great importance, especially for the food industry.
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microalgae biomass was employed for the extraction of valuable bioactive compounds with deep eutectic-based solvents (DESs). Particularly, the Choline Chloride (ChCl) based DESs, ChCl:1,2 butanediol ...(1:4), ChCl:ethylene glycol (1:2), and ChCl:glycerol (1:2) mixed with water at 70/30
/
ratio were used for that purpose. The extracts' total carotenoid (TCC) and phenolic contents (TPC), as well as their antioxidant activity (IC50), were determined within the process of identification of the most efficient solvent. This screening procedure revealed ChCl:1,2 butanediol (1:4)/H
O 70/30
/
as the most compelling solvent; thus, it was employed thereafter for the extraction process optimization. Three extraction parameters, i.e., solvent-to-biomass ratio, temperature, and time were studied regarding their impact on the extract's TCC, TPC, and IC50. For the experimental design and process optimization, the statistical tool Response Surface Methodology was used. The resulting models' predictive capacity was confirmed experimentally by carrying out two additional extractions under conditions different from the experimental design.
In this study, the ethanol production by the mesophilic fungus
Neurospora crassa from BG was studied and optimized concerning the induction of lignocellulose degrading enzymes and the production ...phase as well. The production of cellulolytic and hemicellulolytic enzymes was studied under solid-state cultivation (SSC). SSC in a laboratory horizontal bioreactor using the optimized medium, WS and BG in the ratio 1:1 and initial moisture level 61.5%, allowed the large scale production of the multienzymatic system. Similar yields with those from flasks experiments, as high as 1073,
56,
4.2,
1.6,
3.1,
5.7 and 0.52
U
g
−1 carbon source of xylanase, endoglucanase, cellobiohydrolase, β-glucosidase, α-
l-arabinofuranosidase, acetyl esterase and feruloyl esterase, respectively, were obtained. Chromogenic (fluorogenic) 4-methylumbelliferyl substrates were used to characterize the major activities of the multienzyme component, after the separation by isoelectric focusing (IEF) electrophoresis. Alkali pre-treated BG was used for ethanol production. A yield of about 74
g of ethanol
kg
−1 dry BG (5,
6
g
L
−1) was obtained under optimum conditions (aeration 0.1
vvm, pre-treatment with 1
g NaOH 10
g
−1
dry BG).
Light controls the developmental, physiological, morphological, and metabolic responses of many fungi. Most fungi respond primarily to blue, red, and green light through their respective ...photoreceptors. In this study, a screening of different light wavelengths’ effects on submerged Pleurotus ostreatus cultivation in baffled flasks was conducted. P. ostreatus growth was not inhibited in all tested conditions, while an equal or higher protein content was observed in comparison with dark conditions. Red and green light favored exopolysaccharide (EPS) production while red and blue light favored intracellular polysaccharide (IPS) production. To focus on EPS production, the effect of red and green light wavelengths on the production of the polysaccharide via submerged cultivation of P. ostreatus LGAM 1123 was tested. Submerged cultivation using red light in baffled flasks resulted in EPS production of 4.1 ± 0.4 g/L and IPS content of 23.1 ± 1.4% of dry weight (dw), while green light resulted in EPS production of 4.1 ± 0.2 g/L and 44.8 ± 5.2% dw IPS content. Similar production levels were achieved in a 3.5 L bioreactor using red light. The EPS produced using red light revealed a polysaccharide with a higher antioxidant activity compared to the polysaccharides produced by green light. In addition, the analysis of the crude polysaccharides has shown differences in biochemical composition. The structural differences and β glucan’s existence in the crude polysaccharides were confirmed by FT-IR analysis. Overall, these polysaccharides could be used in the food industry as they can enhance the functional health-promoting, physicochemical, and sensory properties of food products.
As olive leaves constitute the main by-product of the olive oil industry with important environmental and economic impact, there is an increasing demand for its valorization. In the present work, we ...report the development and application of immobilized enzyme batch bioreactors for the chemo-enzymatic treatment of an aqueous
Olea europaea
leaf extract rich in oleuropein to produce an extract enriched in hydroxytyrosol and other oleuropein hydrolysis products. To this end, a robust biocatalyst was developed through the immobilization of β-glucosidase on chitosan-coated magnetic beads which exhibited high hydrolytic stability after 240 h of incubation at 37 °C. The biocatalyst was successfully used in both a rotating bed-reactor and a stir-tank reactor for the modification of the olive leaf extract leading to high conversion yields of oleuropein (exceeding 90%), while an up to 2.5 times enrichment in hydroxytyrosol was achieved. Over 20 phenolic compounds (from different classes of phytochemicals such as flavonoids, secoiridoids, and their derivatives) were identified, in the extract before and after its modification through various chromatographic and spectroscopic techniques. Finally, the biological activity of both extracts was evaluated. Compared to the non-modified extract, the modified one demonstrated 20% higher antioxidant activity, seven-fold higher antibacterial activity, and enhanced cytotoxicity against leiomyosarcoma cells.
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•PVOH/glycerol support the growth of ZnO nanoparticles in chitosan.•Chitosan/PVOH/ZnO films show enhanced mechanical performance and barrier.•Nanocomposites present inhibition ...potential against B. lactofermentum and E. coli.•NaOH treatment hinders the antimicrobial activity of the nanocomposite films.
The current study investigates the performance of chitosan-based ZnO nanocomposite films for antimicrobial packaging applications. ZnO nanoparticles are fabricated from zinc acetate solutions and added in plain chitosan and chitosan/glycerol-, chitosan/poly(vinyl alcohol)- blends at 3, 5 and 7 wt. %. Characteristic diffraction peaks at 31.6°, 34.3° and 36.2° confirm the successful formation and growth of ZnO nanoparticles in chitosan-based films after their immersion in hot NaOH solution. Poly(vinyl alcohol) supports the growth of ZnO in chitosan chains and results in higher strain at break and increased barrier. The antimicrobial activity of the nanocomposite films is high against Brevibacterium lactofermentum, moderate against Escherichia coli and almost absent against Corynobacterium glutamicum. Positive synergies between chitosan-based matrices and ZnO nanoparticles are not however established in terms of antimicrobial properties due to the immersion of the films in NaOH solution which lowers the polycationic character and the solubility of chitosan.
Large quantities of wine lees are produced annually by the wine industry. The high phenolic content makes them unsuitable for disposal in the environment or animal feed without a suitable treatment. ...In this study, wine lees were treated by Pleurotus ostreatus in submerged cultivation, producing a high-value biomass and elevated levels of laccase, an important industrial enzyme. Biomass and laccase production reached 21 g/L and 74,000 Units/L, respectively, at the optimal conditions of initial pH 6.0, 20% v/v wine lees, 30 g/L glucose, and 20 g/L yeast extract, while decolorization and dephenolization rates of the waste were over 90%. The mycelial biomass was rich in proteins and essential amino acids reaching up to 43% and 16% per dry weight, respectively. Carbohydrates and lipids were the second richest bioactive compound in biomass, with values of 29.4 ± 2.7% and 29.5 ± 2.7%, respectively. The crude laccase in the culture supernatant was purified via a simple two-step purification procedure by 4.4-fold with a recovery of 44%. The molecular weight of the enzyme was determined to be 62 kDa via SDS electrophoresis. Enzyme activity was optimal at pH 5.0 and 70 °C. The activation energy of the enzyme was calculated at a value of 20.0 ± 0.2 kJ/mol. The pH stability and thermostability of the purified laccase were studied. The enzyme was remarkably stable at pH 8.0 and at temperatures up to 40 °C. The thermal inactivation energy of the enzyme was determined to be 76.0 ± 1.2 kJ/mol. The thermodynamic parameters (ΔH*, ΔG*, and ΔS*) for the thermal deactivation of the purified laccase at a temperature range of 20–60 °C were: 73.8 ≤ ΔH* ≤ 74.3 kJ·mol−1, 98.7 ≤ ΔG* ≤ 101.9 kJ·mol−1, and −90.5 ≤ ΔS* ≤ −84.3 J·mol−1·K−1. Wine lees could be ideal substrates of fungal cultivation for laccase production and biomass with a high protein content in an eco-friendlier way.
The demand for cheap, healthy, and sustainable alternative protein sources has turned research interest into microbial proteins. Mycoproteins prevail due to their quite balanced amino acid profile, ...low carbon footprint and high sustainability potential. The goal of this research was to investigate the capability of
to metabolize the main sugars of agro-industrial side streams, such as aspen wood chips hydrolysate, to produce high-value protein with low cost. Our results indicate that
LGAM 1123 could be cultivated both in a C-6 (glucose)- and C-5(xylose)-sugar-containing medium for mycoprotein production. A mixture of glucose and xylose was found to be ideal for biomass production with high protein content and rich amino acid profile.
LGAM 1123 cultivation in a 4 L stirred-tank bioreactor using aspen hydrolysate was achieved with 25.0 ± 3.4 g L
biomass production, 1.8 ± 0.4 d
specific growth rate and a protein yield of 54.5 ± 0.5% (g/100 g sugars). PCA analysis of the amino acids revealed a strong correlation between the amino acid composition of the protein produced and the ratios of glucose and xylose in the culture medium. The production of high-nutrient mycoprotein by submerged fermentation of the edible fungus
using agro-industrial hydrolysates is a promising bioprocess in the food and feed industry.
Nowadays, the shelf-life extension of foods is a topic of major interest because of its environmental and economic benefits. For this purpose, various methods like deep-freezing, ...ultra-high-temperature pasteurization, drying methods, use of chemicals, controlled-atmosphere preservation, ionizing irradiation, and were investigated. During the last years, the smart packaging for foods using natural biodegradable components is of great interest because it provides positive environmental fingerprint and high shelf-life extension. In the present work, a new nanostructured composite material, the ZnO/Na-Montmorillonite hybrid, was developed. The high antimicrobial properties of the 3-D ZnO material in combination with the high barrier and strength properties of the 2-D Na-Montmorillonite material provided a high promising component for food smart packaging applications. As an extra innovation of this process, the ZnO nanorods coated the external surface of the Na-Montmorillonite and it was not intercalated into the clay as a pillaring material. This new material was incorporated with a 3% w/w composition with a biodegradable poly(vinyl)alcohol (PVOH) polymeric matrix which also exhibits antimicrobial activity. The final product was tested via XRD, FTIR, SEM, tensile test, water sorption, water vapor permeability, oxygen permeability UV–vis, and anti-microbial activity tests and it exhibited advanced mechanical and antimicrobial properties, especially for a ZnO/Na-Montmorillonite fraction of 4:1.
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