Single Cell Oil Production Research Articles

Symbiotic Associations: Key Factors That Determine Physiology and Lipid Accumulation in Oleaginous Microorganisms.

Symbiosis naturally provides an opportunity for microorganisms to live together by mutual or one-way benefit. In symbiotic relationships, the microorganisms usually overcome the limitations of being free-living. Understanding the symbiotic relationships of oleaginous microorganisms provides potential route for the sustainable production of microbial-based alternative fuels. So far, several studies have been conducted in oleaginous microorganisms for the production of alternative fuels. However, some oleaginous microorganisms require high quantity of nutrients for their growth, and high level of energy and chemicals for harvest and separation of lipid bodies. Symbiotic associations can successfully be applied to address these issues. Of symbiotic associations, lichens and selective species of oleaginous endosymbiotic mucoromycotina have received substantial interest as better models to study the evolutionary relationships as well as single-cell oil production. Construction of artificial lichen system composed of cyanobacteria and oleaginous yeast has been achieved for sustainable production of lipids with minimum energy demand. Recently, endosymbiotic mucoromycotina species have been recognized as potential sources for biofuels. Studies found that endohyphal bacterium influences lipid profiling in endosymbiotic mucoromycotina species. Studies on the genetic factors related to oleaginous characteristics of endosymbiotic mucoromycotina species are scarce. In this regard, this review summarizes the different forms of symbiotic associations of oleaginous microorganisms and how symbiotic relationships are impacting the lipid formation in microorganisms. Further, the review also highlights the importance of evolutionary relationships and benefits of co-culturing (artificial symbiosis) approaches for sustainable production of biofuels.

Valorisation of molasses by oleaginous yeasts for single cell oil (SCO) and carotenoids production

Abstract Two oleaginous yeast strains (Rhodosporodium toruloides and Rhodotorula glutinis) were examined for valorisation of molasses by the production of single cell oil (SCO) and carotenoid pigments. In the batch culture studies, the volumetric productivities of R. toruloides and R. glutinis were 3.41 and 2.47 g L−1 d−1 in the molasses medium, compared to that of 1.75 and 1.47 g L−1 d−1, respectively in the glucose yeast extract mineral (GYM) medium, at 96 h. R. toruloides grown in molasses medium yielded a maximum of 0.295 g of biomass g−1 of substrate consumed; whereas R. glutinis produced 0.226 g of biomass g−1 of the substrate consumed. The lipid contents of R. toruloides and R. glutinis were 53% and 45% in the molasses medium, and 48% and 43% in the GYM medium, respectively. R. glutinis grown in the GYM medium recorded the maximum carotenoid yield (0.045%), volumetric carotenoid productivity (0.027 mg L−1 h−1), and cellular carotenoid content ( 448 μ g g − 1 of cell dry weight). A significant increase in biomass and lipid yield was observed in molasses grown yeast as compared to GYM medium. Oleic acid (C18:1) was the predominant fatty acid present in R. toruloides cultivated in GYM medium. This study confirmed the potential of molasses with low C/N ratio for enhanced lipid production.

Single Cell Oil Production by Oleaginous Yeasts Grown in Synthetic and Waste-Derived Volatile Fatty Acids.

Four yeast isolates from the species—Apiotrichum brassicae, Candida tropicalis, Metschnikowia pulcherrima, and Pichia kudriavzevii—previously selected by their oleaginous character and growth flexibility in different carbon sources, were tested for their capacity to convert volatile fatty acids into lipids, in the form of single cell oils. Growth, lipid yields, volatile fatty acids consumption, and long-chain fatty acid profiles were evaluated in media supplemented with seven different volatile fatty acids (acetic, butyric, propionic, isobutyric, valeric, isovaleric, and caproic), and also in a dark fermentation effluent filtrate. Yeasts A. brassicae and P. kudriavzevii attained lipid productivities of more than 40% (w/w), mainly composed of oleic (>40%), palmitic (20%), and stearic (20%) acids, both in synthetic media and in the waste-derived effluent filtrate. These isolates may be potential candidates for single cell oil production in larger scale applications by using alternative carbon sources, combining economic and environmental benefits.

Conversion of cardoon crop residues into single cell oils by Lipomyces tetrasporus and Cutaneotrichosporon curvatus: process optimizations to overcome the microbial inhibition of lignocellulosic hydrolysates

In the present work, the production of Single Cell Oils (SCOs) from undetoxified cardoon hydrolysates (UCH) was investigated. The raw material was pretreated by acid catalyzed steam explosion at 195 °C for 7.5 min and hydrolysed at high dry matter content to achieve a final hydrolysate containing 90 g L-1 glucose and 9 g L-1 xylose. The different ability of Cutaneotrichosporon curvatus and Lipomyces tetrasporus to overcome the toxic effect of the biomass degradation by-products, mainly furan derivatives, in different growth phases was investigated in different set-ups conditions including four hydrolysates concentrations, (glucose and xylose respectively 30 + 3, 45 + 4, 60 + 6, and 90 + 9 g L-1) and two fermentation modes, batch and fed batch. The results indicated that the inoculum age corresponded to a different metabolism of the furanic aldehydes only in L. tetrasporus. C. curvatus was severely inhibited by UCH in any growth phase. L. tetrasporus cells in the stationary phase (SP) grew in UCH at any concentration, while cells in the exponential phase (EP) grew only at the highest dilution rate. The maximum lipids yields and lipid cell content of 20% and 47% respectively (7.1 g L-1 lipids) were achieved in batch mode using SP-inocula and the highest dilution ratio. The dominant fatty acid was oleic acid (59%). The scale-up to the 2 L bioreactor, in fed-batch mode, increased the lipids concentration up to 12.7 g L-1 and the productivity up to 0.135 g L-1 h-1.

Metal and Phosphate Ions Show Remarkable Influence on the Biomass Production and Lipid Accumulation in Oleaginous Mucor circinelloides.

The biomass of Mucor circinelloides, a dimorphic oleaginous filamentous fungus, has a significant nutritional value and can be used for single cell oil production. Metal ions are micronutrients supporting fungal growth and metabolic activity of cellular processes. We investigated the effect of 140 different substrates, with varying amounts of metal and phosphate ions concentration, on the growth, cell chemistry, lipid accumulation, and lipid profile of M. circinelloides. A high-throughput set-up consisting of a Duetz microcultivation system coupled to Fourier transform infrared spectroscopy was utilized. Lipids were extracted by a modified Lewis method and analyzed using gas chromatography. It was observed that Mg and Zn ions were essential for the growth and metabolic activity of M. circinelloides. An increase in Fe ion concentration inhibited fungal growth, while higher concentrations of Cu, Co, and Zn ions enhanced the growth and lipid accumulation. Lack of Ca and Cu ions, as well as higher amounts of Zn and Mn ions, enhanced lipid accumulation in M. circinelloides. Generally, the fatty acid profile of M. circinelloides lipids was quite consistent, irrespective of media composition. Increasing the amount of Ca ions enhanced polyphosphates accumulation, while lack of it showed fall in polyphosphate.

PRODUCTION OF SINGLE CELL OIL FROM LOCAL ISOLATES OF Rhodotorula glutinis

This study includes isolation and characterization of local isolates of Rhodotorula glutinis. From twenty-seven samples, three isolates showed yeast morphology and pigmented with orange-red. These isolates were subjected to biochemical tests and the results revealed that the three isolates have the characteristics of Rhodotorula glutinis. Effects of different incubation periods on growth and single cell oil (SCO) production showed that a maximum lipid content and productivity was 12.27 g/L and 64.74%, respectively after 4 days of incubation by the strain Rhodotorula glutinis WS9. A study of effect of different carbon sources revealed that the best carbon source for maximum oil production and oil productivity was glucose, which gave 12.15 g/L and 64.38%, respectively. Glucose concentration of 80 g/L gave a maximum oil content (13.76 g/L) and oil productivity (73.97%), whereas glucose 40 g/L concentration supported a maximum yeast growth (18.90 g/L). Ammonium sulfate was the best nitrogenous source to get a maximum dry biomass, lipid content and lipid productivity which reached to the 18.92 g/L, 12.21 g/L and 64.53%, respectively. 1.0% (w/v) ammonium sulfate was optimum for lipid content and lipid productivity which gave 14.96 g/L and 71.88%, respectively. Initial pH effects study revealed that the optimal initial pH was 6.5 which recorded 18.99 g/L, 12.23 g/L and 64.40% for dry biomass, lipid content and productivity, respectively.

Sync between leucine, biotin and citric acid to improve lipid production by Yarrowia lipolytica on crude glycerol-based media

The use of biodiesel-derived glycerol as a carbon source for single cell oil (SCO) production is a biorefinery engineering strategy that aims to valorize the by-product waste and make the microbial lipid production process more cost-effective. This work aimed to improve the capacity of Yarrowia lipolytica to produce large amounts of lipids and replace genetic engineering by a metabolic approach based on the stimulation of the rate-limiting enzymes and reducing the activation energy thereby increasing the rate of lipids synthesis. The effects of biotin and leucine addition on the lipid content of Y. lipolytica have been investigated. The lipid content of Y. lipolytica was strongly influenced by the addition of biotin. In fact, an increase in biotin concentration from 25 μg/L to 200 μg/L practically increased the lipid concentration up to 15 g/L. Besides, to channel metabolic flux into lipid biosynthesis, the addition of citric acid as lipid precursor led to an increase in total catabolism activation and lipid accumulation to reach around 63% (w/w). The biochemical approach can be a useful target for improving the efficiency of lipid-producing yeast strain rather than genetic engineering.

Dual production of bioenergy in heterotrophic cultures of cyanobacteria: Process performance, carbon balance, biofuel quality and sustainability metrics

This research evaluated the dual production of bioenergy in heterotrophic cultures of cyanobacteria. Process performance parameters, carbon balance, single-cell oil production, biofuel quality, volatile organic compounds (VOCs) generation, and sustainability metrics and impact indicators were assessed. The results showed biomass productivity of 1.03 kg/m³/d. Biomass (63.9%) and VOCs (8.56%) were the main products formed from the conversion of the substrate in the bioreactor. For single-cell-oil production, it is possible to obtain 0.18 kg/m³/d of lipid with this bioprocess. It was determined the fatty acid profile and the quality of biodiesel properties, meeting the requirements established by national and international standards. Besides, the 22 volatile compounds identified presented the energy potential of 122,205.00 kJ/kg and a power generation rate of 10,580.5 kg/m3/d. From an environmental point of view, the net energy ratio was 0.13, while the eight mid-points impact categories resulted in an ecotoxicity potential of 430.86 CTUe, energy resources of 230.04 MJ, global warming of 171.05 kg CO2 eq, photochemical oxidation of 1.33 kg O3 eq, water footprint of 1.08 m³, acidification of 0.44 kg SO2 eq, eutrophication of 0.13 kg N eq, and ozone depletion of kg 1.83 × 10−5 CFC-11 eq, per functional unit of 1 m³ of the bioreactor, operating for 5 days. Finally, the proposed process can be considered as a promising strategy for renewable energy production from microalgae.

Ranking of By-products for Single Cell Oil Production. Case of Latvia

Abstract Single cell oil is considered as a promising alternative to fish and vegetable oils. Due to the ability of oleaginous microorganisms to produce significant amounts of polyunsaturated fatty acids such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), single cell oil can be used for human and animal consumption. In this context, marine microorganisms of the class Labyrinthulomycetes are particularly highlighted in scientific literature. In order to clarify the possibilities for the use of microorganisms of the class Labyrinthulomycetes in large-scale single cell oil production, the first step is to gain awareness of the cultivation conditions required for these microorganisms. In addition, to reduce the cost of single cell oil production, it is necessary to identify potential agroindustrial waste products that are suitable for microbiological cultivation of Labyrinthulomycetes. This article examines the potential biotechnological applications of Labyrinthulomycetes in single cell oil production, the cultivation conditions, nutritional requirements, inhibitors and suitable waste products. In addition, an agroindustrial by-product availability analysis has been carried out. The article evaluates agroindustrial by-products based on their availability in Latvia, required pre-treatment, price, shelf life and efficiency.

Single-cell oil production by Mortierella isabellina DSM 1414 using different sugars as carbon source.

Pure carbon sources, especially carbohydrates which are raw materials deriving from agro-industrial processes, are often used for small-scale single-cell oil production by fermentation. The aim of this study was to investigate the effects of different pure carbon sources on cell growth, lipid accumulation, and γ-linolenic acid (GLA) production by the filamentous fungus Mortierella isabellina DSM 1414 (Deutsche Sammlung von Mikroorganismen). The sugars utilized in this study are found extensively and abundantly in nature, especially in food raw materials and, in consequence, in agro-food industry wastes or surpluses. Thus, the potential of many waste materials containing these sugars to be used in the production of single-cell oil by fermentation could also be evaluated. The effects of the sugars utilized on cell growth, biomass production, and lipid production were investigated. Fatty acids were also analysed in the lipids produced at the end of the fermentations. Results showed that the maximum biomass production was 10.80 g/L in lactose-based media, while the maximum oil production was 5.44 g/L in maltose-based media. Oleic (20.42%-42.94%), palmitic (14.96%-22.19%), and stearic (9.00%-26.92%) acids were the major fatty acids along with linoleic acid (11.35%-18.67%) and GLA (3.56%-8.04%). The production of GLA as the target fatty acid was remarkable. This study indicates that agro-industrial waste including most of the sugars utilized (except for arabinose and sucrose with lipid production of 0.81 and 0.28 g/L, respectively) can be employed for production of single-cell oil by M. isabellina DSM 1414 which contains a high amount of GLA.

Two-step optimization process for grass hydrolysate application as biodiesel feedstock with novel quality characteristics.

A major obstacle to biodiesel commercialization is supplying feedback which increases production costs. The potential of some oleaginous yeast for conversion of waste materials to biodiesel feedstock can overcome this problem. In this study, a potential oleaginous yeast strain was used for single-cell oil (SCO) production. Two sets of experiments were designed for the optimization process. According to the results obtained from the first experiment, lipid production and lipid content of this strain increased from 1.96g/L and 22.6% to 3.85g/L and 35.18% by optimization of grass hydrolysis, respectively. The results of the second experiment indicate an increase in SCO production and lipid content to 7.28g/L and 56.39%, respectively. These results were obtained when HNO3 was used for substrate pre-treatment. Lipid analysis by gas chromatography-mass spectrometry showed a suitable and high potential of fatty acid profile for biodiesel production, which was then confirmed by evaluating the physicochemical properties of the biodiesel obtained in compliance with the US and EU standards. Consumption of microbial oil and low-cost substrate can compensate the high costs of feedstock in biodiesel production.

Phosphate as a limiting factor for the improvement of single cell oil production from Yarrowia lipolytica MUCL 30108 grown on pre-treated distillery spent wash

One of the major environmental problems is the industrial waste called vinasse, also known as Distillery Spent Wash (DSW) produced in large amount by ethanol distilleries. In this study, we aimed at to improve the production of single cell oil (SCO) using the oleaginous yeast Yarrowia lipolytica MUCL30108 on DSW and to determine the main factor influencing biomass production. Growth of Y. lipolytica was assessed on DSW with modifications of the effluent for biomass production. Chemical acid hydrolysis, enzymatic hydrolysis with cellulases and hemicellulases, or by mobilizing the hydrolytic tools of Aspergillus niger MUCL19001 were used as pretreatment to improve sugar release in the effluent and to improve yeast biomass production. Subsequently, the impact of pH adjustment and of vitamins, glucose and minerals supplementation was investigated to understand the specific nutritional and physiological limitations of the yeast biomass production. The pretreatment of DSW with A. niger cellular extracts provided the highest release of reducing sugars (up to 5.65 g/L), principally composed of glucose and a 30 % increase in yeast biomass production as compared to crude DSW. Additionally, addition of potassium phosphate resulted in a significant improvement of the yeast biomass production, reaching up to 70 % increase as compared to crude DSW without affecting the lipid content of the yeast biomass. The microbial lipids produced were mainly composed of fatty acids suitable for biodiesel valorisation. Globally, our findings suggested that phosphate, but not the carbon source, was the major limiting factor for growth of the yeast in raw DSW.

Scale-up strategy for yeast single cell oil production for Rhodotorula mucilagenosa IIPL32 from corn cob derived pentosan

This work was aimed to strategically scale-up the yeast lipid production process using Reynolds number as a standard rheological parameter from 50 mL to 50 L scale. Oleaginous yeast Rhodotorula mucilaginosa IIPL32 was cultivated in xylose rich corncob hydrolysate. The fermentation process for growth and maturation was operated in fed-batch with two different C/N ratios of 40 and 60. The hydrodynamic parameters were used to standardize and represent the effect of rheology on the fermentation process. The growth pattern of the yeast was found similar in both shake flask and fermenter with the maximum growth observed at 48 h. The lipid yield increased from 0.4 g/L and 0.5 g/L to 1.3 g/L and 1.83 g/L for 50 mL to 50 L for C/N ratio 40 and 60 respectively. The increase in productivity during the growth phase and lipid accumulation during the maturation phase showed that the scale-up strategy was successful.

Transforming Candida hispaniensis, a promising oleaginous and flavogenic yeast.

Candida hispaniensis is an oleaginous yeast with a great potential for production of single cell oil according to its naturally high lipid accumulation capacity. Its unusual small genome size trait is also attractive for fundamental research on genome evolution. Our physiological study suggests a great potential for lipid production, reaching 224 mg/g of cell dry weight in glucose minimum medium. C. hispaniensis is also able to secrete up to 34.6 mg/L of riboflavin promising further riboflavin production improvements by cultivation optimization and genetic engineering. However, while its genome sequence has been released very recently, no genetic tools have been described up to now for this yeast limiting its use for fundamental research and for exploitation in an industrial biotechnology. We report here the first genetic modification of C. hispaniensis by introducing a heterologous invertase allowing the growth on sucrose using a biolistic transformation approach using a dedicated vector. The first genetic tool and transformation method developed here appear as a proof of concept, and while it would benefit from further optimization, heterogeneous expression of invertase allows for metabolism of an additional sugar and shows heterologous enzyme production capacity.

Single cell oil production by a novel yeast Trichosporon mycotoxinivorans for complete and ecofriendly valorization of paddy straw

Abstract Background Oleaginous yeasts can be grown on different carbon sources, including lignocellulosic hydrolysate containing a mixture of glucose and xylose. However, not all yeast strains can utilize both the sugars for lipogenesis. Therefore, in this study, efforts were made to isolate dual sugar-utilizing oleaginous yeasts from different sources. Results A total of eleven isolates were obtained, which were screened for their ability to utilize various carbohydrates for lipogenesis. One promising yeast isolate Trichosporon mycotoxinivorans S2 was selected based on its capability to use a mixture of glucose and xylose and produce 44.86 ± 4.03% lipids, as well as its tolerance to fermentation inhibitors. In order to identify an inexpensive source of sugars, nondetoxified paddy straw hydrolysate (saccharified with cellulase), supplemented with 0.05% yeast extract, 0.18% peptone, and 0.04% MgSO4 was used for growth of the yeast, resulting in a yield of 5.17 g L−1 lipids with conversion productivity of 0.06 g L−1 h−1. Optimization of the levels of yeast extract, peptone, and MgSO4 for maximizing lipid production using Box–Behnken design led to an increase in lipid yield by 41.59%. FAME analysis of single cell oil revealed oleic acid (30.84%), palmitic acid (18.28%), and stearic acid (17.64%) as the major fatty acids. Conclusion The fatty acid profile illustrates the potential of T. mycotoxinivorans S2 to produce single cell oil as a feedstock for biodiesel. Therefore, the present study also indicated the potential of selected yeast to develop a zero-waste process for the complete valorization of paddy straw hydrolysate without detoxification. How to cite: Sagia S, Sharma A, Singh S, et al. Single cell oil production by a novel yeast Trichosporon mycotoxinivorans for complete and ecofriendly valorization of paddy straw. Electronic Journal of Biotechnology 2020;44. https://doi.org/10.1016/j.ejbt.2020.01.009 .

Single Cell Oil Production by Wild Type Strain Lipomyces starkeyi Y604

As one of the promising oleaginous yeast, Lipomyces starkeyi has emerged as a great candidate of a single cell oil (SCO) producer. This is due to its ability to accumulate high lipid content and its ability to consume a diverse carbon sources. However, lipid production of the wild type strain is limited and efforts to obtain high producing wild-type strain are demanded. For this purpose, we conducted fermentation of the local wild-type strain of L. starkeyi InaCC Y604, derived from the collections of Indonesian Culture Collection (InaCC). In this study, we employed glucose, xylose, and a combination of glucose and xylose as carbon sources and conducted the fermentation in the batch flask scale. Following the fermentation, parameters such as dry cell weight (DCW), carbon source consumption, SCO production, lipid content and lipid yield were determined. In this study, we obtained that L. starkeyi InaCC Y604 grown in medium contained a mixture of glucose (50 g/L) and xylose (50 g/L) accumulate highest SCO production with 57.04±0.94 g/L and its lipid content reached out 0.17±0.00 w/w. Despite the result is not the best among previous reported literatures, this shows that the Indonesian local strain L. starkeyi InaCC Y604 can be a promising candidate to be further optimized.

Single cell oil production and modification for fuel and food applications: Assessing the potential of sugarcane molasses as culture medium for filamentous fungus

Sugarcane molasses (SM) a low-cost substrate was used for single-cell oil production by Mucor circinelloides. Cultivations were carried out with diluted molasses at a concentration of 40 g sugars L−1 with and without nutrients supplementation. The best performance in regard to the lipid productivity (0.66 g L−1 day−1), biomass (11.2 g L−1) and lipid content (29 wt.%) was attained in a medium containing SM supplemented with minor nutrients. The profile of fatty acid composition revealed suitable properties for biodiesel synthesis, although high levels of polyunsaturated fatty acids (PUFA) were also found, which may suggest the possibility of using the oleaginous biomass from Mucor circinelloides URM 4182 as feedstock to yield both products. Concentrated solutions of polyunsaturated fatty acids (PUFA) were obtained by enzymatic hydrolysis of the acylglycerol structures, while biodiesel was prepared by direct transesterification of the oleaginous biomass using acid heterogeneous catalyst.

Biodiesel-derived crude glycerol as alternative feedstock for single cell oil production by the oleaginous yeast Candida viswanathii Y-E4

In recent years, much attention has been paid to microbial lipids as promising raw materials for biodiesel production. The use of industrial by-products as carbon sources seems to be a feasible strategy for cost-effective lipid fermentation with oleaginous microorganisms on a large scale. In this work, biodiesel-derived crude glycerol was used as a renewable feedstock for microbial lipid production. Chemical characterization has shown that used crude glycerol sample is mainly composed of 64.5 % glycerol, 5.9 % methanol, 11 % water and 5.8 % ash in addition to other impurities. This industrial waste was used as only carbon source in the culture media of 13 oleaginous yeast strains. Candida viswanathii Y-E4 stood out above the other strains, achieving a higher amount of biomass and lipid content (17.2 g/L and 41 %, respectively). Culture conditions were optimized using response surface methodology to enhance the Y-E4 lipid yield. Box-Behnken model was performed to determine the optimum levels of three independent variables and the eventual effect of their interactions on the response. Under optimal conditions, the total biomass of 26.6 g/L with lipid content of 51.9 % (corresponding to a lipid yield of 13.6 g/L) could be achieved after 166 h of culture. The characterization of obtained lipid showed that fatty acids composition and lipid profile were very different between pure and crude glycerol based cultures, with a predominance of long-chain fatty acids, particularly polyunsaturated fatty acids such as linoleic acid (45 %). The predictive determination of biodiesel properties suggests that this oil may effectively be used for biodiesel manufacture. The current study, therefore, opens new perspectives in relation to the valorization of biodiesel-derived crude glycerol, through completely eco-friendly processes.

Techno-economic analysis and life cycle assessment of heterotrophic yeast-derived single cell oil production process

The widespread application and utilization of vegetable oils and fats has led to a significant increase of their annual production. Fats and oils are mainly consumed as food and as animal feed, as raw material in the chemical industry and more recently as raw material for biofuel production. In this work the economics of the biochemical production of microbial oil is investigated and the life cycle assessment is performed for first time in the open literature. The production process is simulated using commercial simulators to perform accurate material and energy balances and all necessary data are collected from the open literature. Following the process simulation step a detailed technoeconomic analysis is performed and the fixed capital investment is estimated for a production that varies from 2 to 40 kt of microbial oil per year. Having completed the technoeconomic analysis the Life Cycle Inventory Analysis is performed, and the environmental impacts are estimated, using the comprehensive Life Cycle Assessment methodology.

Co‐fermentation of agricultural and industrial waste by Naganishia albida for microbial lipid production in fed‐batch fermentation

AbstractBACKGROUNDOleaginous yeast Naganishia albida is well known for its ability to utilize a variety of carbon sources, including lignocellulosic hydrolysates, complex sugars and fatty acids. In this study, crude glycerol derived from the biodiesel industry and onion waste hydrolysate (OWH) were used as potential substrates for microbial lipid production.RESULTSBoth substrates provided sufficient nutrition to support cell growth and lipid production as sole carbon source. Enhanced lipid production and cell growth rate were observed with supplementation of yeast extract as nitrogen source. Co‐fermentation of OWH and crude glycerol led to improved biomass as well as lipid production. The highest lipid content of 34.0% (w/w) with 21.1 g L−1 of dry cell weight was obtained after 168 h of fed‐batch fermentation with intermittent feeding of crude glycerol and OWH. The lipid concentration was approximately 7 times higher than using mineral medium with crude glycerol as sole carbon source, where a lipid content of 12.6% (w/w) and a maximum biomass of 8.32 g L−1 were obtained at 168 h.CONCLUSIONOptimization of glycerol and OWH feeding could enhance lipid accumulation in N. albida. This study suggests that the co‐fermentation of agricultural and industrial waste as substrates can provide a competitive route for single cell oil production. © 2019 Society of Chemical Industry