Influence of different reactor types on Nannochloropsis oculata microalgae culture for lipids and fatty acid production

Greenhouse gases emitted into the atmosphere by burning of fossil fuels cause global warming. One option is obtaining biodiesel. Nannochloropsis oculata was cultured under different light intensities and reactors at 25°C for 21 days with f/2 medium to assess their effects on cell density, lipid, and fatty acids (FAs). N. oculata improved cell density on fed-batch glass tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹, yielding 3.5 × 10⁸ cells ml⁻¹, followed by fed-batch Erlenmeyer flask (1 L) at 650 μmol E m⁻² s⁻¹ with 1.7 × 10⁸ cells ml⁻¹. The highest total lipid contents (% g lipid × g dry biomass⁻¹) were 44.4 ± 0.8% for the reactor (1 L) at 650 μmol E m⁻² s⁻¹ and 35.2 ± 0.2% for the tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹, until twice as high compared with the control culture (Erlenmeyer flask 1 L, 80 μmol E m⁻² s⁻¹) with 21.2 ± 1%. Comparing the total lipid content at 200 μmol E m⁻² s⁻¹, tubular reactor (7 L) and reactor 1 L achieved 35.2 ± 0.2% and 28.3 ± 1%, respectively, indicating the effect of shape reactor. The FAs were affected by high light intensity, decreasing SFAs to 2.5%, and increased monounsaturated fatty acids + polyunsaturated fatty acids to 2.5%. PUFAs (20:5n-3) and (20:4n-3) were affected by reactor shape, decreasing by half in the tubular reactor. In the best culture, fed-batch tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹ contains major FAs (16:0; 38.06 ± 0.16%), (16:1n-7; 30.74 ± 0.58%), and (18:1n-9; 17.15 ± 0.91%).     

Comparative studies on the lipid profiles of female and male gonads of abalone (Haliotis discus hannai)

Lipid profiles of the lipids from female gonads (LFG) and male gonads (LMG) of abalones (Haliotis discus hannai) were evaluated based on the analysis of phospholipid (PL) molecular species, PL class composition, fatty acid (FA) composition, and lipid class composition. These results suggested that lipids from abalone gonads were abundant in omega-3 polyunsaturated FA (n − 3 PUFA, 14.42%–18.27% of total FAs) and PLs including phosphatidylcholine (PC, 21.26–47.85 mg g⁻¹) and phosphatidylethanolamine (PE, 9.29–24.10 mg g⁻¹). Furthermore, more than 60 molecular species of PC and PE were determined. Particularly, the molecular species containing n − 3 PUFA including eicosapentaenoic acid (EPA) constituted majority of PC and PE in LFG and LMG. By contrast, LFG contained more PC and PE species containing EPA. Considering the lipid profiles, abalone gonads are a potential source of PL-form n − 3 PUFA.     

Characteristics of Oil from Hulless Barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.) Bran from Tibet

The bran of hulless barley (Hordeum vulgare L.) from Tibet was investigated. This paper reports on the physicochemical characteristics, lipid classes and fatty acids of the oil from the bran. The petroleum (60–90 °C) extract of hulless barley bran was found to be 8.1%. The investigated physiochemical parameters included density at 40 °C (0.96 g/cm³), refractive index at 40 °C (1.41), melting point (30.12 °C), acid value (11.6 mg KOH/g), peroxide value (19.41 μg/g), saponification value (337.62 mg KOH/g), iodine value (113.51 mg iodine/g) and unsaponifiable matter (4.5% of total lipids).The amount of neutral lipids in the crude oil was the highest (94.55% of total lipids), followed by glycolipids (4.20% of the total lipid) and phospholipids (1.25% of the total lipid). Linoleic acid (75.08% of total fatty acids) followed by palmitic acid (20.58% of total fatty acids), were the two major fatty acids in the oil. The results show that the oil from the hulless barley bran could be a good source of valuable essential fatty acids.     

Free Fatty Acids Reduction in Waste Cooking Oil by Rhodosporidium toruloides and Simultaneous Carotenoids,Lipids, and PAL Enzyme Production in a Two-Phase Culture System

Waste cooking oil (WCO) is a problematic waste product that contains free fatty acids (FFAs), preventing it from being valorized easily as biodiesel and poses an environmental hazard if incorrectly disposed. The use of WCO as a carbon source for Rhodosporidium toruloides (R. toruloides) using a two-phase culture system is developed. The normal growth of R. toruloides when cultured in WCO (OD₆₀₀ 52) reveals its ability to use a hydrophobic substrate as the carbon source compared to glucose (OD₆₀₀ 51.9). Interestingly, the extracellular lipase activity when R. toruloides is grown on WCO is 14.4 U mL⁻¹ compared to when grown on glucose (2.4 U mL⁻¹). Additionally, FFA levels in WCO are reduced from 2% to 0.2% at end of fermentation, suggesting that R. toruloides can consume FFA. Furthermore, higher yield of beneficial products: β-carotene (4.57 µg mL⁻¹), torularhodin (4.2 µg mL⁻¹), fatty acids (1 mg mL⁻¹), and phenylalanine ammonia-lyase (PAL) enzyme (0.12 µmol mg⁻¹) are produced when WCO is the carbon source, compared to glucose (4.1 µg mL⁻¹ β-carotene, 3.0 µg mL⁻¹ torularhodin, 1 mg mL⁻¹ of fatty acids, and 0.096 µmol mg⁻¹ PAL enzyme). This is a first study that shows R. toruloides can grow on hydrophobic carbon source.     

Effect of a Seaweed Extract on Fatty Acid Accumulation and Glycerol-3-Phosphate Dehydrogenase Activity in 3T3-L1 Adipocytes

This study was to determine the effect of a seaweed Ascophyllum nodosum extract (SE) containing 220 mg g⁻¹ phlorotannins on differentiation and fatty acid accumulation in differentiating 3T3-L1 adipocytes. 3T3-L1 cells (2 × 10⁴ mL⁻¹) were seeded to 24-well plates and proliferated to reach confluence and then were treated with media containing 0, 12.5, 25, 50, 75 and 100 μg mL⁻¹ SE for 8 days. Dexamethasone, methyl-isobutylxanthine and insulin (DMI) were added to the media in the first 2 days to induce cell differentiation. On day 8 the adipocytes were harvested for measuring cellular fatty acid concentration and the activity of glycerol-3-phosphate dehydrogenase (GPDH). It was found that treatment with SE increased (P < 0.01, n = 6) cellular myristoleic acid (C14:1), palmitoleic acid (C16:1) and oleic acid (C18:1) and total monounsaturated fatty acids (MUFA) without significantly affecting the cell number and saturated fatty acid (SFA). Ratios of MUFA/SFA, C14:1/C14:0, C16:1/C16:0 and C18:1/C18:0 in cellular lipids increased (P < 0.05, n = 6) with the SE treatment in a dose dependent manner (P < 0.001). Treatment with 75 μg mL⁻¹ SE depressed (P < 0.05) cellular GPDH activity. The results indicate that the biological factors in the SE may be involved in differentiation and MUFA accumulation in adipocytes.     

Growth Temperature and Salinity Impact Fatty Acid Composition and Degree of Unsaturation in Peanut-Nodulating Rhizobia

Growth and survival of bacteria depend on homeostasis of membrane lipids, and the capacity to adjust lipid composition to adapt to various environmental stresses. Membrane fluidity is regulated in part by the ratio of unsaturated to saturated fatty acids present in membrane lipids. Here, we studied the effects of high growth temperature and salinity (NaCl) stress, separately or in combination, on fatty acids composition and de novo synthesis in two peanut-nodulating Bradyrhizobium strains (fast-growing TAL1000 and slow-growing SEMIA6144). Both strains contained the fatty acids palmitic, stearic, and cis-vaccenic + oleic. TAL1000 also contained eicosatrienoic acid and cyclopropane fatty acid. The most striking change, in both strains, was a decreased percentage of cis-vaccenic + oleic (≥80% for TAL1000), and an associated increase in saturated fatty acids, under high growth temperature or combined conditions. Cyclopropane fatty acid was significantly increased in TAL1000 under the above conditions. De novo synthesis of fatty acids was shifted to the synthesis of a higher proportion of saturated fatty acids under all tested conditions, but to a lesser degree for SEMIA6144 compared to TAL1000. The major adaptive response of these rhizobial strains to increased temperature and salinity was an altered degree of fatty acid unsaturation, to maintain the normal physical state of membrane lipids.     

Regiospecificity profiles of storage and membrane lipids from the gill and muscle tissue of atlantic salmon (Salmo salar L.) grown at elevated temperature

Regiospecific and traditional analysis, of both storage and membrane lipids, was performed on gill, white muscle, and red muscle samples taken from Atlantic salmon (Salmo salar) to gauge the effect of elevated water temperature. The fish, fed a commercial diet, were held at an elevated water temperature of 19°C. Total n-3 PUFA, total PUFA, and n-3/n-6 and unsaturated/saturated fatty acid (UFA/SFA) ratios in the FA profile of the total lipid extract in the white muscle were fairly low compared with fish grown at 15°C. Adaptation of structural and storage lipids at elevated temperatures was shown by a significant (P<0.01) reduction in PUFA especially in the percentage of EPA (6–8%). Further adaptation was indicated by the percentages of SFA, which were significantly (P<0.05) higher in gill (56%) and white muscle (58%) polar lipid fractions and coincided with lower percentages of n-3, n-6, and total PUFA. The regiospecific profiles indicated a high affinity of DHA to the sn-2 position in both the TAG (61–68%) and polar lipid (35–60%) fractions. The combination of detailed regiospecific and lipid analyses demonstrated adaptation of cell membrane structure in Atlantic salmon grown at an elevated water temperature.     

High Saturated Fat Diet Alters the Lipid Composition of Triacylglycerol and Polar Lipids in the Femur of Dam and Offspring Rats

Previous work has shown that dietary lipids alter femur lipid composition. Specifically, we have shown that exposure to high saturated fatty acid (SFA) diets in utero, during suckling, or post‐weaning alters femur total lipid composition, resulting in higher percent bone mass in males and females and bone mineral density (BMD) in female offspring with no effect on bone mineral outcomes in dams. Comparatively, high n‐3 polyunsaturated fatty acid (PUFA) diets increase femur polar (PL) lipid n‐3 content, which has been associated with increased bone mineral content and strength. However, the extent that PL or triacylglycerol (TAG) lipids change with high SFA diets is unknown. The current investigation examined the influence of a high SFA diet (20 % lard by weight) on femur PL and TAG lipid composition in 5‐month old female Wistar rats (fed high SFA diet from age 28 days onwards; dams) and their 19‐day old offspring (exposed to high SFA in utero and during suckling; pups). High SFA exposure resulted in increased monounsaturates and decreased n‐3 and n‐6 PUFA in the TAG fraction in both dams and pups, and higher SFA and n‐6:n‐3 ratio in dams only. The PL fraction showed decreased n‐6 PUFA in both dams and pups. The magnitude of the diet‐mediated responses, specifically TAG 18:1 and PL n‐6 PUFA, may have contributed to the previously reported altered BMD, which was supported with correlation analysis. Future research should investigate the relationship of diet‐induced changes in bone lipids on bone structure, as quantified through micro‐computed tomography.     

Evaluation of a Yarrowia lipolytica Strain Collection for Its Lipid and Carotenoid Production Capabilities

The oleaginous yeast Yarrowia lipolytica is capable of accumulating large amounts of fatty acids in the form of lipids which can serve as a platform polymer for a variety of applications. Additionally, through heterologous gene expression, Y. lipolytica is capable of producing carotenoids. Due to the observation that Y. lipolytica exhibits a high phenotypic inter‐strain variability, robotics and microwell scale cultivations are applied to examine 12 wild type strains of a Y. lipolytica collection. The strains are characterized with respect to their metabolic capabilities for fatty acid production as well as genetically manipulated to produce beta‐carotene. Furthermore, growth and production behavior of the strain collection at different temperatures as well as initial pH are assessed. A molecular discrimination between the strains is achieved by internal transcribed spacer (ITS)‐sequencing and polymerase chain reaction (PCR)‐based methods. The best performing strain with respect to lipid production produces ≈2% lipids per dry cell weight (DCW) and 8 mg g^?1 beta‐carotenoids in yeast nitrogen base (YNB) media. All strains show robust growth from 28 to 34 °C. Practical Applications: Unlocking nature's potential by screening natural isolates shows that even on inter‐strain level sufficient phenotypic diversity may arise. Automated growth‐based characterization of beta‐carotene‐producing strains in terms of media composition, effect of initial pH, and temperature tolerance shows that with modern cultivation techniques, rapid characterization of strain collections is feasible. Combining results of beta‐carotene and lipid formation could help to balance both pathways to improve the storage of hydrophobic compounds in the lipid droplets. The generalized findings could be further transferred to improve the production of any valuable compound, derived from the mevalonate pathway.     

Low-temperature total oxidation of methane by pore- and vacancy-engineered NiO catalysts

Designing methane combustion catalysts operated under low temperature (<400°C) remains a huge challenge, especially for noble-metal–free catalytic systems. With NaCl as a crystalline scaffold, NiO catalyst with abundant oxygen vacancies and an ultra-high–specific surface area of 181 m² g⁻¹ is obtained. The mesoporous NiO exhibits outstanding CH₄ combustion performance (T₉₀ = 370°C at the weight hourly space velocity (WHSV) = 20,000 mL g⁻¹ h⁻¹). X-ray photoelectron spectroscopy (XPS), H₂-temperature-programmed reduction (TPR), kinetic measurements, and O¹⁸ isotope-labeling experiments together disclose the key role of surface lattice oxygen and reaction mechanism by NiO catalysts. More importantly, the excellent stability of NiO by doping La was obtained (low-temperature thermal stability: 385°C, 400 h, 4 vol% H₂O).     

High pyroelectric performance in Pb0.99Nb0.02[(Zr0.57Sn0.43)0.94Ti0.06]0.98O3/Al2O3 composites by design

High pyroelectric performance around human body temperature is essential for ultra-sensitive infrared detectors of medical systems. Herein, toward human health monitoring, composite ceramics (1-x)Pb_0.99Nb_0.02[(Zr_0.57Sn_0.43)_0.94Ti_0.06]_0.98O₃/xAl₂O₃ (x = 0, 0.1, and 0.2) were designed. A metastable ferroelectric (FE) phase was induced in the anti-FE matrix by the Al₂O₃ component-induced internal stress, and in turn FE-anti-FE phase boundary was constructed. The ceramics at x = 0.2 exhibit high pyroelectric coefficient with p = 10.9 × 10⁻⁴ C·m⁻²·K⁻¹ and figures of merit with current responsivity F_i = 6.23 × 10⁻¹⁰ m·V⁻¹, voltage responsivity F_v = 12.71 × 10⁻² m²·C⁻¹, and detectivity F_d = 7.03 × 10⁻⁵ Pa^−1/2 around human body temperature. Moreover, the enhanced pyroelectric coefficients exist in a broad operation temperature range with a large full width at half maximums of 18.5°C and peak value of 29.2 × 10⁻⁴ C·m⁻²·K⁻¹ at 48.2°C. The designed composite ceramic is a promising candidate for infrared thermal imaging technology of noncontact human health monitoring system.     

Creating new water-soluble Iso- and n-fatty acid arginate hydrochloride with antimicrobial properties

Typically, short- and long-chain lipids from oils exhibit different antimicrobial activities and therefore have been used in agriculture and aquaculture, biomedical therapeutic and antibacterial fields. However, these fatty acids have limitations in terms of bioactive efficacy, thermostability and aqueous solubility. In this study, water-soluble iso-fatty acid arginate hydrochloride derivatives with antimicrobial properties were produced by introducing branched (iso-) chain and other linear- (n-) chain fatty acids to the “arginine” amino acid molecule. The two-step synthetic route was straightforward and provided an efficient 88% and 76% product yields for ethyl n-oleoyl arginate hydrochloride and ethyl iso-oleoyl arginate hydrochloride, respectively. ATR-FT-IR, NMR, and LC-MS-Q-TOF techniques were used to thoroughly characterize and confirm the products. These arginate products had strong antimicrobial activities against Listeria innucua, a Gram-positive bacterium with minimum inhibitory concentrations and minimum bactericidal concentrations ranging from 1.8 µg mL⁻¹ to 29.1 µg mL⁻¹. Therefore, the study demonstrated the development of a novel class of antimicrobial compounds from iso-fatty acids and arginates.     

Seasonal study of the lipid composition in different tissues of the common octopus (Octopus vulgaris)

Seasonal variation of octopus (Octopus vulgaris) lipid composition was investigated in four tissues: arm, mantle, ovary and digestive gland. A non‐homogeneous fat distribution was observed, with the digestive gland exhibiting a higher (p <0.05) lipid content than the other tissues. The ovary showed a higher (p <0.05) fat content than both muscle tissues, reaching its highest (p <0.05) value in winter. Neutral lipids – free fatty acids (FFA), triacylglycerols, and sterols (ST) – exhibited their highest (p <0.05) concentrations in the digestive gland and their lowest (p <0.05) values in muscle tissues. The phospholipid (PL) content of the ovary was the highest (p <0.05) of all tissues analysed, with the PL content also being significantly (p <0.05) higher in the digestive gland than in arm and mantle. The concentrations of most lipid classes (FFA, PL and ST) exhibited a seasonal variation. The fatty acid composition showed a remarkable difference between the digestive gland and all other tissues analysed. Thus, the digestive gland exhibited higher (p <0.05) contents in monounsaturated fatty acids and also lower (p <0.05) contents in both saturated (SFA) and polyunsaturated (PUFA) fatty acids. The highest mean values in SFA and PUFA were observed in ovary and muscle tissues, respectively. A seasonal effect was observed for SFA and PUFA.     

Effects of thermal treatment on fish lipids‐amylose interaction

The paper describes a study on effects of thermal treatments (microwave heating and freezing) on fish lipids‐amylose starch interactions. Particular attention was paid to lipid availability (extractability from the system) and contribution of fatty acids to various groups of lipids after interactions produced by mixing, microwave heating and storage. Analyses were made on model systems containing fish lipids at different oxidation levels and gelatinised with 10% aqueous solution of amylose starch. The lipid:starch ratio was 1:1. The systems were assayed before and after mixing, microwave heating (4 min, 90 W), freezing (30 d, –18 °C), and heating followed by freezing. Lipid extractability (selective extraction), peroxide value (PV), anisidine value (AsV), fluorescence, and fatty acid profiles (GC/MS) were determined. Mixing of fish lipids with amylose was shown to result in lipid‐amylose interaction. The thermal treatments applied (microwave heating or freezing at –19 °C for 30 d) were observed to exert different, significant effects on fish lipids‐amylose starch interactions. The effects depended also on the extent of lipid oxidation. Fatty acids of the lipids were bound selectively, PUFA, and particularly DHA, were subjected to stronger binding and higher amounts of those acids were bound.     

Physicochemical Characteristics and Functional Properties of Seed Oil from Four Different Cultivars of S. Wilsoniana

A study is conducted to explore the under-utilized resources of Swida wilsoniana seed oil (SWSO). Physicochemical properties of four cultivars of SWSO and their fatty acid composition, phytochemicals, oxidation stabilities, and antioxidant capacities are evaluated. The results indicate that SWSO is abundant in unsaturated fatty acids (76.02–82.43%) and contained a high phytochemical content. Gamma-tocotrienol (206.03 ± 0.21–215.84 ± 0.17 mg kg⁻¹), β-amyrin (107.12 ± 0.27–192.30 ± 1.17 mg kg⁻¹), and betulin (32.82 ± 0.59–88.20 ± 0.37 mg kg⁻¹) are major components of SWSO compared to familiar oils. The induction period (5.08–5.80 h) is negatively correlated with unsaturated fatty acid content (r = −0.948^**, P < 0.01), particularly linoleic acid (r = −0.938^**, P < 0.01). A high antioxidant capacity is observed in SWSO which is primarily attributed to tocopherol/tocotrienol content (0.832^*–0.963^**). SWSO can be regarded as a new resource and a high-quality ingredient for dietary foods and other applications. Practical applications: The favorable physicochemical characteristics and functional properties of SWSO indicate that it may be used as a novel and daily edible oil through moderate refining. It also exhibits promise to protect the artery and liver as a special oil for use as shortening and frying because of its ideal FAC and antioxidant capacity. In addition, SWSO may be suitable for the cosmetics industry. Furthermore, more varieties should be obtained to verify and refine the correlations between chemical composition and antioxidant properties. In addition, the specific phenolics in SWSO should be identified to better characterize the relationship between polyphenol content and antioxidant capacity.     

Fabrication and thermal conductivity of highly porous alumina body from platelets with yeast fungi as a pore forming agent

A highly porous alumina body was fabricated by heating a green clinker body consisting of platelets and yeast fungi as a pore forming agent. Four kinds of alumina platelets were used. When green clinker bodies of platelet aggregates (A11) with 10 and 30 mass% of yeast fungi were heated at 1500 °C for 2 h, their porosities reached 72% and 78%, respectively. In contrast, when the green clinker bodies composed of platelets with an average size of 10 µm and an aspect ratio of 25–30 (SERATH①), and 20 mass% of yeast fungi were heated at 1400 °C for 2 h, the porosity of the resultant porous alumina body was also approximately 72%. However, the room temperature thermal conductivities of the porous alumina bodies with 72% porosity derived from A11 and SERATH① were 0.86 and 0.50 W m⁻¹ K⁻¹, respectively. The decrease in the thermal conductivity of the porous alumina body produced from SERATH① is caused by the long path route for heat transfer.     

Effect of cobalt oxide on characteristics of micro-arc oxidation coatings on TC11 alloy

In order to improve the comprehensive performance of TC11 titanium alloy and make it more widely used in the field of oil and gas wells, cobalt oxide micro-powder from 0 to 0.8 g·L⁻¹ was added in the electrolyte. The effects of cobalt oxide micro-powder concentration on properties of micro-arc oxidation (MAO) coatings were analyzed by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical workstation. With cobalt oxide micro-powder increased, the oxide voltage increased, and the discharge coating micropores became more uniform. The increase in thickness and hardness also improved corrosion resistance. The comprehensive performance after added 0.6 g·L⁻¹ of cobalt oxide was the best, with a doubling increase in thickness and hardness, reaching 32.1 µm and 721.2 HV, respectively. The corrosion rate reduced to 4.19 × 10⁻¹⁰ mm·a⁻¹, which reduced by three orders of magnitude. In addition, the substrates and samples prepared with 0.6 g·L⁻¹ cobalt oxidation were used for the erosion corrosion tests in different NaCl solutions, and it was found that the weight loss and rate of the MAO sample (slight corrosion) were lower than substrates, indicating that the cobalt oxide doped coatings had better corrosion resistance.     

Supercritical carbon dioxide extraction of microalgae lipid: Process optimization and laboratory scale-up

Supercritical carbon dioxide (SC-CO₂) extraction of lipid from Scenedesmus sp. for biodiesel production was investigated and compared to conventional extraction methods. The effect of biomass pre-treatment prior to extraction and extracting conditions, namely pressure in the range of 200–500 bar, temperatures in the range of 35–65 °C and CO₂ flow rate in the range of 1.38–4.02 g min⁻¹, on SC-CO₂ extraction yield and quality of lipid were investigated. Three levels full factorial design of experiments and response surface methodology was used to model the system. A second order polynomial model was developed and used to predict the optimum conditions. Scaling up to a laboratory larger scale was also tested. The results indicated that SC-CO₂ extraction was superior to other extraction techniques, but exhibited significant variations in yield with changes in operating parameters. In the developed model, it was found that the linear and quadratic terms of the temperature, as well as the interaction with pressure had a significant effect on lipid yield; whereas, their effect on lipid quality was insignificant. The best operating conditions, in the tested range, were 53 °C, 500 bar and 1.9 g min⁻¹, in which lipid extraction yield of 7.41% (dry weight basis) was obtained. Negligible differences were observed when the fatty acid composition of SC-CO₂ extracted lipid was compared to that extracted by the conventional methods. At the optimum conditions, SC-CO₂ extraction was successfully scaled-up by eight-folds and the extracted lipid yield dropped by 16%.     

Enhanced corrosion resistance of layered double hydroxides/steam coating composite coating prepared by the hydrothermal method on LA43M magnesium–lithium alloy substrates

An excellent anticorrosion Mg–Al layered double hydroxide (LDH) composite coating was successfully fabricated on LA43M magnesium alloy substrates via an in situ steam coating (SC) process and a subsequent hydrothermal treatment at different temperatures. The microstructure, composition and phase formation of the composite coatings were studied via X-ray diffractometer, energy disperse spectroscopy, and scanning electron microscope, respectively. The corrosion resistance of composite coatings was further investigated using electrochemical measurements and corrosion test. The results showed that LDH/SC composite coating has typical nanosheets microstructure, which effectively seal the defects of SC. As the hydrothermal temperature increases, the thickness and density of nanosheets increases, and the corrosion resistance was significantly improved. Especially, the Mg–Al LDH/SC composite coating prepared at 100°C was the most dense and thickness, and exhibited the optimal and long-term anticorrosion resistance in 3.5 wt.% NaCl soultion. It has the lowest I_corr (1.767 × 10⁻⁸ A/cm²), which decreased by three and two orders of magnitude compared with the bare substrate and SC. Furthermore, it can maintain good chemical stability after immersion in the corrosion medium for 192 h and its hydrogen evolution rate (0.00416 mL·cm⁻²·h⁻¹) and weight lost rate (0.00266 mg·cm⁻²·h⁻¹) were the lowest compared with other samples.