Substrate For Lipid Production Research Articles

Utilization of Sugarcane Bagasse as a Substrate for Lipid Production by Aurantiochytrium sp.

Thraustochytrid, Aurantiochytrium sp., produces various lipids such as polyunsaturated and saturated fatty acids, carotenoids, and other hydrocarbons, which are useful in the fields of health foods, cosmetics, fine chemicals, and biofuels. Lignocellulosic biomass, which is abundant and cheap, is a promising feedstock for producing cheaper bulk and high-value-added products using Aurantiochytrium sp. However, the steam explosion of lignocellulosic biomass for efficient enzymatic saccharification generates substances that inhibit the growth of microorganisms. In this study, the inhibitory activities of these by-products on the growth and lipid production of Aurantiochytrium sp. were investigated. Aurantiochytrium sp. was found to be highly sensitive to furfural and vanillin and moderately sensitive to 5-hydroxymethylfurfural and syringaldehyde. Washing steam-exploded bagasse with water, followed by activated charcoal treatment, significantly reduced furfural, which was a major inhibitory component in the saccharified solution.

Wax ester production in nitrogen-rich conditions by metabolically engineered Acinetobacter baylyi ADP1

Metabolic engineering can be used as a powerful tool to redirect cell resources towards product synthesis, also in conditions that are not optimal for the production. An example of synthesis strongly dependent on external conditions is the production of storage lipids, which typically requires a high carbon/nitrogen ratio. This requirement also limits the use of abundant nitrogen-rich materials, such as industrial protein by-products, as substrates for lipid production. Acinetobacter baylyi ADP1 is known for its ability to produce industrially interesting storage lipids, namely wax esters (WEs). Here, we engineered A. baylyi ADP1 by deleting the gene aceA encoding for isocitrate lyase and overexpressing fatty acyl-CoA reductase Acr1 in the wax ester production pathway to allow redirection of carbon towards WEs. This strategy led to 3-fold improvement in yield (0.075 ​g/g glucose) and 3.15-fold improvement in titer (1.82 ​g/L) and productivity (0.038 ​g/L/h) by a simple one-stage batch cultivation with glucose as carbon source. The engineered strain accumulated up to 27% WEs of cell dry weight. The titer and cellular WE content are the highest reported to date among microbes. We further showed that the engineering strategy alleviated the inherent requirement for high carbon/nitrogen ratio and demonstrated the production of wax esters using nitrogen-rich substrates including casamino acids, yeast extract, and baker’s yeast hydrolysate, which support biomass production but not WE production in wild-type cells. The study demonstrates the power of metabolic engineering in overcoming natural limitations in the production of storage lipids.

Improvement of lipid production from an oil-producing filamentous fungus, Penicillium brevicompactum NRC 829, through central composite statistical design

In the present study, 13 filamentous fungi were screened for their lipid production and an oleaginous fungus, Penicillium brevicompactum NRC 829, was found to be the highest lipid producer. Screening of various agro-industrial residues was performed and sunflower oil cake proved to be the best substrate for lipid production. A central composite design was employed to investigate the optimum concentrations of the most significant medium components required to improve the lipid production by P. brevicompactum. The results clearly revealed that the maximal lipid production of 8.014 ± 0.06 gL−1 (representing 57.6% lipid/dry biomass) was achieved by the fungus when grown for 6 days at 30 °C under static condition in a medium containing sunflower oil cake, NaNO3 and KCl at final concentrations of 8, 0.75 and 0.25 gL−1, respectively. Gas chromatography-mass spectrometry analysis of P. brevicompactum lipid indicated that linoleic acid (LA) (C18:2–6, 9) was the most abundant fatty acid, accounting for up to 62% of the total fatty acid profile, followed by palmitoleic acid (C16:1, 16%) and linolenic acid (C18:3, 8%). These results suggest that P. brevicompactum NRC 829 may have potential for commercial development for the production of LA by fermentation using cheap raw material.

Lipid production from fed-batch fermentation of crude glycerol directed by the kinetic study of batch fermentations

Oleaginous yeast Trichosporon oleaginosus was cultivated in crude glycerol as substrate for lipid production in a 15L fermenter. The impact of weight carbon to nitrogen ratio (C/N) including 20, 30, 45 and 60 on lipid production from the strain was investigated in batch fermentations. The highest biomass and lipid concentration of 24.80g/L and 12.14g/L, respectively was observed during the fermentation at C/N ratio of 45. C/N ratio of 30 showed a comparable concentration of biomass (23.70g/L) and lipid (11.26g/L). Based on the kinetic study of the batch fermentations, fed-batch fermentation was designed and conducted. In the fed-batch fermentation, the maximum concentration of biomass and lipid was 43.82g/L and 21.87g/L, respectively at C/N ratio of 45.

Evaluation of Waste Loquat Kernels as Substrate for Lipid Production by Rhodotorula glutinis SO28

This study was performed to produce lipids from the isolated oleaginous yeast Rhodotorula glutinis SO28 using loquat kernel extract (LKE) as substrate. LKE was prepared using acid hydrolysis and alkaline neutralization steps. Lipid production was performed in shaking flaks culture. Even if LKE was used as a sole source of nutritional substances, it could support cell growth and lipid synthesis in the yeast. Additional carbon, nitrogen and phosphorus sources were found to significantly alter the lipid accumulation potential of the yeast. Optimal concentrations of additional carbon (glucose) and nitrogen (ammonium sulphate) sources for lipid accumulation were determined as 15 and 0.5 g/L, respectively. On the other hand, all the concentrations of additional phosphorus source were found to significantly reduce the lipid accumulation. Optimal incubation time was determined as 132 h. Under the optimized culture conditions, the lipid concentration and lipid content of the yeast were determined as 7.82 g/L and 62 %, respectively. Fatty acid methyl ester analysis exhibited that this yeast strain could produce high proportions of C16:0 and C18 fatty acids, which are ideal for biodiesel production. This is the first report on the use of waste loquat kernels as substrate for microbial lipid production.

Organic fraction of municipal solid waste as a suitable feedstock for the production of lipid by oleaginous yeast Cryptococcus aerius

The detoxified pre-hydrolysate and enzymatic hydrolysate of OFMSW were used as substrates for lipid production by Cryptococcus aerius. Factorial experimental designs were employed for the optimization of dilute acid pre-hydrolysis, detoxification by over-liming, enzymatic hydrolysis, and lipid production. OFMSW pre-hydrolysis with 3% H2SO4 for 45min was found to be the optimal treatment, resulted in total sugar concentration of 65.5g/L (32.8% yield, based on grams of total reducing sugar per gram of OFMSW). The optimal detoxification conditions of the pre-hydrolysate by over-liming was incubation at 30°C and pH 11 for 24h, resulted in the reduction of total nitrogen, total phenolic compounds, and furans by 51.3%, 45.1%, and 100%, respectively. The residual solid was subjected to enzymatic hydrolysis, and the highest sugar concentration of 30.5g/L was obtained. At optimal conditions, the yeast cultivation on the detoxified pre-hydrolysate and enzymatic hydrolysate resulted in the lipid production of 3.9g/L (12.8% yield, based on g lipid per g consumed sugar) and 4.3g/L (17.1% yield, based on g lipid per g consumed sugar), respectively. The elemental analysis showed the presence of heavy metals including iron (925mg/l), zinc (59mg/l), lead (4.7mg/l), and nickel (3.5mg/l) in the pre-hydrolysate, which were significantly reduced by the over-liming detoxification.

Application of magnesium sulfate and its nanoparticles for enhanced lipid production by mixotrophic cultivation of algae using biodiesel waste

CG (Crude glycerol) is one of the major wastes of biodiesel production process. It can be used as a substrate for lipid production by algae and the produced lipid can be recycled as a feedstock for biodiesel production. In order to avoid substrate inhibition, lipid production media are prepared by diluting the CG with distilled water. However, CG contains only a small amount of Mg (57.41 ± 18 ppm) and its concentration is further decreased to around 0.57 ppm during the dilution process. Apart from having a number of roles in algal physiology, Mg is the central atom of chlorophyll. Therefore, MgSO4 was evaluated as a Mg source to supplement the CG based media used for lipid production by Chlorella vulgaris. By supplementing the process with 1 g/L of MgSO4, nearly 185.29 ± 4.53% improvement in lipid production has been achieved. Further, application of MgSO4 nanoparticles was found to improve the lipid production by 118.23 ± 5.67%. Interestingly, unlike MgSO4, its nanoparticles were found to enhance the lipid production at the expense of only a small amount of glycerol. Thus, application of MgSO4 nanoparticles could be a potential strategy for enhanced lipid yield.

Suitability of Low-Cost Sugars as Substrates for Lipid Production by the Fungus Thamnidium elegans

Thamnidium elegans CCF-1465 was grown in a submerged shake-flask culture in media in which inexpensive sugars derived from a sugar refinery plant (glucose, fructose, and sucrose) were utilized as carbon sources. Cultures were performed in media favoring the accumulation of reserve lipid (high initial C/N ratios imposed, media presenting constant initial nitrogen and increasing initial sugar concentrations, namely, at 30, 60, and 80 g/L). Although significant quantities of fat were accumulated in all cultures performed, lipid production in terms of both absolute (g/L) and relative (%, wt/wt, in dry matter) values clearly increased with sugar concentration increments into the medium. For a given initial sugar concentration, regardless of the individual sugar utilized, lipid was accumulated in almost equivalent quantities inside the mycelia. Sugars were assimilated with comparable consumption rates, while consumption rate was divided into two distinct phases, especially in the high initial sugar concentratio...