Kinetics of lipid production at lab scale fermenters by a new isolate of Yarrowia lipolytica SKY7

Effect of Argan Oil on Lipid Production by Yarrowia lipolytica NRRL YB-423

The aim of this study was to investigate the effects of different concentrations of traditional, industrial, and cosmetic argan oils on lipid production by Yarrowia lipolytica NRRL YB-423 in a glucose-based medium. This study also explored the influence of different nitrogen concentrations on lipid and biomass production. Traditional argan oil had the highest oleic acid amount, whereas industrial and cosmetic argan oils had a higher linoleic acid amount. A lipid accumulation of 4.18 g/l was achieved with industrial argan oil, equivalent to approximately 65% lipid yield based on the dry cell weight. In addition, the results indicated that higher concentrations of argan oil led to increased lipid production. Correlation analysis showed that the addition of argan oil caused a change in fatty acid composition and an increase in linoleic acid amount. Linoleic acid increased in the presence of cosmetic argan oil (0.5 ml). The same effect was observed in the presence of 2 ml of traditional or industrial argan oil. In addition, when the amount of additional nitrogen was increased to 1 g/l, oleic acid amount increased in the control group. The nitrogen concentration used along with the argan oil type also caused changes in the correlations. The industrial argan oil group differed from the other groups in the presence of 1 g/l N. On the contrary, in the presence of an additional 0.5 g/l N, the industrial and traditional argan oil groups were closely correlated with each other.

A systematic review on utilization of biodiesel-derived crude glycerol in sustainable polymers preparation

With the rapid development of biodiesel, biodiesel-derived glycerol has become a promising renewable bioresource. The key to utilizing this bioresource lies in the value-added conversion of crude glycerol. While purifying crude glycerol into a pure form allows for diverse applications, the intricate nature of this process renders it costly and environmentally stressful. Consequently, technology facilitating the direct utilization of unpurified crude glycerol holds significant importance. It has been reported that crude glycerol can be bio-transformed or chemically converted into high-value polymers. These technologies provide cost-effective alternatives for polymer production while contributing to a more sustainable biodiesel industry. This review article describes the global production and quality characteristics of biodiesel-derived glycerol and investigates the influencing factors and treatment of the composition of crude glycerol including water, methanol, soap, matter organic non-glycerol, and ash. Additionally, this review also focused on the advantages and challenges of various technologies for converting crude glycerol into polymers, considering factors such as the compatibility of crude glycerol and the control of unfavorable factors. Lastly, the application prospect and value of crude glycerol conversion were discussed from the aspects of economy and environmental protection. The development of new technologies for the increased use of crude glycerol as a renewable feedstock for polymer production will be facilitated by the findings of this review, while promoting mass market applications.

Integrated fermentative process for lipid and β-carotene production from acetogenic syngas fermentation using an engineered oleaginous Yarrowia lipolytica yeast

An engineered Yarrowia lipolytica strain was successfully employed to produce β-carotene and lipids from acetic acid, a product of syngas fermentation by Clostridium aceticum. The strain showed acetic acid tolerance up to concentrations of 20 g/L. Flask experiments yielded a peak lipid content of 33.7 % and β-carotene concentration of 13.6 mg/g under specific nutrient conditions. The study also investigated pH effects on production in bioreactors, revealing optimal lipid and β-carotene contents at pH 6.0, reaching 22.9 % and 44 mg/g, respectively. Lipid profiles were consistent across experiments, with C18:1 being the dominant compound at approximately 50 %. This research underscores a green revolution in bioprocessing, showing how biocatalysts can convert syngas, a potentially polluting byproduct, into valuable β-carotene and lipids with a Y. lipolytica strain.

Second generation Pichia pastoris strain and bioprocess designs

Yeast was the first microorganism used by mankind for biotransformation processes that laid the foundations of industrial biotechnology. In the last decade, Pichia pastoris has become the leading eukaryotic host organism for bioproduct generation. Most of the P. pastoris bioprocess operations has been relying on toxic methanol and glucose feed. In the actual bioeconomy era, for sustainable value-added bioproduct generation, non-conventional yeast P. pastoris bioprocess operations should be extended to low-cost and renewable substrates for large volume bio-based commodity productions. In this review, we evaluated the potential of P. pastoris for the establishment of circular bioeconomy due to its potential to generate industrially relevant bioproducts from renewable sources and waste streams in a cost-effective and environmentally friendly manner. Furthermore, we discussed challenges with the second generation P. pastoris platforms and propose novel insights for future perspectives. In this regard, potential of low cost substrate candidates, i.e., lignocellulosic biomass components, cereal by-products, sugar industry by-products molasses and sugarcane bagasse, high fructose syrup by-products, biodiesel industry by-product crude glycerol, kitchen waste and other agri-food industry by products were evaluated for P. pastoris cell growth promoting effects and recombinant protein production. Further metabolic pathway engineering of P. pastoris to construct renewable and low cost substrate utilization pathways was discussed. Although, second generation P. pastoris bioprocess operations for valorisation of wastes and by-products still in its infancy, rapidly emerging synthetic biology tools and metabolic engineering of P. pastoris will pave the way for more sustainable environment and bioeconomy. From environmental point of view, second generation bioprocess development is also important for waste recycling otherwise disposal of carbon-rich effluents creates environmental concerns. P. pastoris high tolerance to toxic contaminants found in lignocellulosic biomass hydrolysate and industrial waste effluent crude glycerol provides the yeast with advantages to extend its applications toward second generation P. pastoris strain design and bioprocess engineering, in the years to come.

Yarrowia lipolytica Strains and Their Biotechnological Applications: How Natural Biodiversity and Metabolic Engineering Could Contribute to Cell Factories Improvement

Among non-conventional yeasts of industrial interest, the dimorphic oleaginous yeast Yarrowia lipolytica appears as one of the most attractive for a large range of white biotechnology applications, from heterologous proteins secretion to cell factories process development. The past, present and potential applications of wild-type, traditionally improved or genetically modified Yarrowia lipolytica strains will be resumed, together with the wide array of molecular tools now available to genetically engineer and metabolically remodel this yeast. The present review will also provide a detailed description of Yarrowia lipolytica strains and highlight the natural biodiversity of this yeast, a subject little touched upon in most previous reviews. This work intends to fill this gap by retracing the genealogy of the main Yarrowia lipolytica strains of industrial interest, by illustrating the search for new genetic backgrounds and by providing data about the main publicly available strains in yeast collections worldwide. At last, it will focus on exemplifying how advances in engineering tools can leverage a better biotechnological exploitation of the natural biodiversity of Yarrowia lipolytica and of other yeasts from the Yarrowia clade.

Lipid bioproduction from delignified native grass (Cyperus distans) hydrolysate by Yarrowia lipolytica

In the present study, native grass (Cyperus distans) was utilized for the production of lipid using Yarrowia lipolytica MTCC 9519. Initially, pretreatment methods using hydrothermal and alkaline delignification were performed to obtain cellulose rich liquid fractions. Delignified native grass biomass was enzymatically hydrolyzed to convert non fermentable sugars in to fermentable sugars. The growth of Y. lipolytica MTCC 9519 by utilizing pretreated native grass hydrolysate was evaluated. The yield and concentration of total reducing sugars after enzyme hydrolysis were found to be 378 ± 35 mg/g of pretreated biomass and 28.64 g/L ± 1.25 g/L, respectively. When pretreated, delignified native grass hydrolysate was used with (NH₄)₂SO₄ (30C/N ratio) and sodium n-octanoate (0.4% w/w), the dry cell weight and lipid accumulation of Y. lipolytica MTCC 9519 reached about 19.88 ± 1.54 g/L and 53.62% (w/w) respectively after 96 h. Thus, native grass could become a promising substrate for biolipid production.

The white-rot fungus, Phanerochaete chrysosporium, under combinatorial stress produces variable oil profiles following analysis of secondary metabolites

AIMS

The effects of combinatorial stress on lipid production in Phanerochaete chrysosporium remain understudied. This species of white-rot fungi was cultivated on solid-state media while under variable levels of known abiotic and biotic stressors to establish the effect upon fungal oil profiles.

METHODS AND RESULTS

Environmental stressors induced upon the fungus included the following: temperature, nutrient limitation and interspecies competition to assess impact upon oil profiles. Fatty acid type and its concentration were determined using analytical methods of gas chromatography and mass spectrometry. Growth rate under stress was established using high-performance liquid chromatography with ergosterol as the biomarker. Fungi grown on solid-state agar were able to simultaneously produce short- and long-chain fatty acids which appeared to be influenced by nutritional composition as well as temperature. Addition of nitrogen supplements increased the growth rate, but lipid dynamics remained unchanged. Introducing competition-induced stress had significantly altered the production of certain fatty acids beyond that of the monoculture while under nutrient-limiting conditions. Linoleic acid concentrations, for example, increased from an average of 885 ng μl^-1 at monoculture towards 13 820 ng μl^-1 at co-culture, following 7 days of incubation.

CONCLUSIONS

Interspecies competition produced the most notable impact on lipid production for solid-state media cultivated fungi while the addition of nitrogen supplementation presented growth and lipid accumulation to be uncorrelated. Combinatorial stress therefore influences the yield of overall lipid production as well as the number of intermediate fatty acids produced, deriving similar oil profiles to the composition of vegetable and fish oils.

SIGNIFICANCE AND IMPACT OF THE STUDY

Fungal secondary metabolism remains highly sensitive following combinatorial stress. The outcome impacts the research towards optimizing fungal oil profiles for biomass and nutrition. Future investigations on fungal stress tolerance mechanisms need to address these environmental factors throughout the experimental design.

Metabolic engineering for increased lipid accumulation in Yarrowia lipolytica - A Review

Current energy security and climate change policies encourage the development and utilization of bioenergy. Oleaginous yeasts provide a particularly attractive platform for the sustainable production of biofuels and industrial chemicals due to their ability to accumulate high amounts of lipids. In particular, microbial lipids in the form of triacylglycerides (TAGs) produced from renewable feedstocks have attracted considerable attention because they can be directly used in the production of biodiesel and oleochemicals analogous to petrochemicals. As an oleaginous yeast that is generally regarded as safe, Yarrowia lipolytica has been extensively studied, with large amounts of data on its lipid metabolism, genetic tools, and genome sequencing and annotation. In this review, we highlight the newest strategies for increasing lipid accumulation using metabolic engineering and summarize the research advances on the overaccumulation of lipids in Y. lipolytica. Finally, perspectives for future engineering approaches are proposed.

Cost, energy and GHG emission assessment for microbial biodiesel production through valorization of municipal sludge and crude glycerol

In this study, cost simulations were made based on 20 million L blended biodiesel B-10 production per year using INRS and conventional process. In case of INRS process, microbial lipid was produced by T. oleaginosus using washed municipal secondary sludge fortified with crude glycerol while lipid was extracted from wet biomass using biodegradable surfactant and petroleum-diesel (PD). The conventional process uses commercial substrates for lipid production and organic solvents for lipid extraction from dry biomass. The unit B-10 production cost of INRS process was estimated to be $ 0.72/L for an annual capacity of 20 million L, which is 9.5 times more economical than conventional biodiesel production process. For INRS process, the unit B-10 biodiesel production cost was sensitive to plant capacity and lipid productivity during the fermentation. INRS process exhibited positive net energy gain and positive GHG capture, which proves to be energetically and environmentally viable.

Application of de-lignified cellulose to enhance intracellular and extracellular lipid production from oleaginous yeast using acetic acid

Two de-lignified cellulose of loofah sponge and sawdust were applied in two ways to enhance the lipid production from oleaginous yeast using acetic acid. When 30 g/L of acetic acid was used as a carbon source, direct addition of de-lignified loofah sponge or sawdust increased the extracellular lipid content to 33.94% and 53.25%, respectively. The latter reduced the energy input of lipid extraction process from 0.86 to 0.57 GJ per ton of biodiesel production. To relieve the inhibition caused by 40 g/L acetic acid, immobilization of oleaginous yeast on de-lignified sawdust increased the lipid concentration and yield from 3.83 g/L, 0.18 g/g C to 7.15 g/L, 0.20 g/g C, respectively. These improvements occurred due to the cell-immobilized sawdust which play an important role in the loading of cells and adsorption of acetic acid. Immobilized cultivation also increased the fatty acid proportion of C18:1, thereby improving biodiesel performance.

A review on variation in crude glycerol composition, bio-valorization of crude and purified glycerol as carbon source for lipid production

Crude glycerol (CG) is a by-product formed during the trans-esterification reaction for biodiesel production. Although crude glycerol is considered a waste stream of the biodiesel industry, it can replace expensive carbon substrates required for lipid production by oleaginous micro-organisms. However, crude glycerol has several impurities, such as methanol, soap, triglycerides, fatty acids, salts and metals, which are created during the trans-esterification process and may affect the cellular metabolism involved in lipid synthesis. This review aims to critically present a variation in crude glycerol composition depending on trans-esterification process and impact of impurities present in the crude glycerol on the cell growth and lipid accumulation by oleaginous microbes. This study also draws comparison between purified and crude glycerol for lipid production. Several techniques for crude glycerol purification (chemical treatment, thermal treatment, membrane technology, ion-exchange chromatography and adsorption) have been presented and discussed with reference to cost and environmental effects.

Biodiesels from microbial oils: Opportunity and challenges

Although biodiesel has been extensively explored as an important renewable energy source, the raw materials-associated cost poses a serious challenge on its large-scale commercial production. The first and second generations of biodiesel are mainly produced from usable raw materials, e.g. edible oils, crops etc. Such a situation inevitably imposes higher demands on land and water usage, which in turn compromise future food and water supply. Obviously, there is an urgent need to explore alternative feedstock, e.g. microbial oils which can be produced by many types of microorganisms including microalgae, fungi and bacteria with the advantages of small footprint, high lipid content and efficient uptake of carbon dioxide. Therefore, this review offers a comprehensive picture of microbial oil-based technology for biodiesel production. The perspectives and directions forward are also outlined for future biodiesel production and commercialization.

Valorization of papaya fruit waste through low-cost fractionation and microbial conversion of both juice and seed lipids

Seed oil from papaya waste was validated as a novel carbon substrate for Yarrowia lipolytica to produce high-value products.

Effect of glucose on poly-γ-glutamic acid metabolism in Bacillus licheniformis

Background

Poly-gamma-glutamic acid (γ-PGA) is a promising macromolecule with potential as a replacement for chemosynthetic polymers. γ-PGA can be produced by many microorganisms, including Bacillus species. Bacillus licheniformis CGMCC2876 secretes γ-PGA when using glycerol and trisodium citrate as its optimal carbon sources and secretes polysaccharides when using glucose as the sole carbon source. To better understand the metabolic mechanism underlying the secretion of polymeric substances, SWATH was applied to investigate the effect of glucose on the production of polysaccharides and γ-PGA at the proteome level.

Results

The addition of glucose at 5 or 10 g/L of glucose decreased the γ-PGA concentration by 31.54 or 61.62%, respectively, whereas the polysaccharide concentration increased from 5.2 to 43.47%. Several proteins playing related roles in γ-PGA and polysaccharide synthesis were identified using the SWATH acquisition LC–MS/MS method. CcpA and CcpN co-enhanced glycolysis and suppressed carbon flux into the TCA cycle, consequently slowing glutamic acid synthesis. On the other hand, CcpN cut off the carbon flux from glycerol metabolism and further reduced γ-PGA production. CcpA activated a series of operons (glm and epsA-O) to reallocate the carbon flux to polysaccharide synthesis when glucose was present. The production of γ-PGA was influenced by NrgB, which converted the major nitrogen metabolic flux between NH₄⁺ and glutamate.

Conclusion

The mechanism by which B. licheniformis regulates two macromolecules was proposed for the first time in this paper. This genetic information will facilitate the engineering of bacteria for practicable strategies for the fermentation of γ-PGA and polysaccharides for diverse applications.

Electronic supplementary material

The online version of this article (doi:10.1186/s12934-017-0642-8) contains supplementary material, which is available to authorized users.