Direct enzymatic ethanolysis of potential Nannochloropsis biomass for co-production of sustainable biodiesel and nutraceutical eicosapentaenoic acid

Efficient Expression and Application of a Modified Rhizomucor miehei Lipase for Simultaneous Production of Biodiesel and Eicosapentaenoic Acid Ethyl Ester from Nannochloropsis Oil

Few reports exist on one-step enzymatic methods for the simultaneous production of biodiesel and eicosapentaenoic acid ethyl ester (EPA-EE), a high-value pharmaceutical compound. This study aimed to efficiently express Rhizomucor miehei lipase (pRML) in Pichia pastoris X-33 via propeptide mutation and high-copy strain screening. The mutated enzyme was then used to simultaneously catalyze the production of both biodiesel and EPA-EE. The P46N mutation in the propeptide (P46N-pRML) significantly boosted its production, with the four-copy strain increasing enzyme yield by 3.7-fold, reaching 3425 U/mL. Meanwhile, its optimal temperature increased to 45-50 °C, pH expanded to 7.0-8.0, specific activity doubled, Km reduced to one-third, and kcat/Km increased 7-fold. Notably, P46N-pRML efficiently converts Nannochloropsis gaditana oil's eicosapentaenoic acid (EPA). Under optimal conditions, it achieves up to 93% biodiesel and 92% EPA-EE yields in 9 h. Our study introduces a novel, efficient one-step green method to produce both biodiesel and EPA-EE using this advanced enzyme.

Extraction of Nannochloropsis Fatty Acids Using Different Green Technologies: The Current Path

Nannochloropsis is a genus of microalgae widely recognized as potential sources of distinct lipids, particularly polyunsaturated fatty acids (PUFA). These may be obtained through extraction, which has conventionally been performed using hazardous organic solvents. To substitute such solvents with "greener" alternatives, several technologies have been studied to increase their extraction potential. Distinct technologies utilize different principles to achieve such objective; while some aim at disrupting the cell walls of the microalgae, others target the extraction per se. While some methods have been utilized independently, several technologies have also been combined, which has proven to be an effective strategy. The current review focuses on the technologies explored in the last five years to extract or increase extraction yields of fatty acids from Nannochloropsis microalgae. Depending on the extraction efficacy of the different technologies, distinct types of lipids and/or fatty acids are obtained accordingly. Moreover, the extraction efficiency may vary depending on the Nannochloropsis species. Hence, a case-by-case assessment must be conducted in order to ascertain the most suited technology, or tailor a specific one, to be applied to recover a particular fatty acid (or fatty acid class), namely PUFA, including eicosapentaenoic acid.

Recent Advances in Feedstock and Lipase Research and Development towards Commercialization of Enzymatic Biodiesel

Biodiesel is a biodegradable, renewable, and carbon-neutral alternative to petroleum diesel that can contribute to the global effort of minimizing the use of fossil fuels and meeting the ever-growing energy demands and stringent environmental constraints. The aim of this work was to (1) review the recent progress in feedstock development, including first, second, third, and fourth-generation feedstocks for biodiesel production; (2) discuss recent progress in lipase research and development as one of the key factors for establishing a cost-competitive biodiesel process in terms of enzyme sources, properties, immobilization, and transesterification efficiency; and (3) provide an update of the current challenges and opportunities for biodiesel commercialization from techno-economic and social perspectives. Related biodiesel producers, markets, challenges, and opportunities for biodiesel commercialization, including environmental considerations, are critically discussed.

Biodiesel and flavor compound production using a novel promiscuous cold-adapted SGNH-type lipase (HaSGNH1) from the psychrophilic bacterium Halocynthiibacter arcticus

BACKGROUND

Biodiesel and flavor compound production using enzymatic transesterification by microbial lipases provides mild reaction conditions and low energy cost compared to the chemical process. SGNH-type lipases are very effective catalysts for enzymatic transesterification due to their high reaction rate, great stability, relatively small size for convenient genetic manipulations, and ease of immobilization. Hence, it is highly important to identify novel SGNH-type lipases with high catalytic efficiencies and good stabilities.

RESULTS

A promiscuous cold-adapted SGNH-type lipase (HaSGNH1) from Halocynthiibacter arcticus was catalytically characterized and functionally explored. HaSGNH1 displayed broad substrate specificity that included tert-butyl acetate, glucose pentaacetate, and p-nitrophenyl esters with excellent stability and high efficiency. Important amino acids (N83, M86, R87, F131, and I173F) around the substrate-binding pocket were shown to be responsible for catalytic activity, substrate specificity, and reaction kinetics. Moreover, immobilized HaSGNH1 was used to produce high yields of butyl and oleic esters.

CONCLUSIONS

This work provides a molecular understanding of substrate specificities, catalytic regulation, immobilization, and industrial applications of a promiscuous cold-adapted SGNH-type lipase (HaSGNH1) from H. arcticus. This is the first analysis on biodiesel and flavor synthesis using a cold-adapted halophilic SGNH-type lipase from a Halocynthiibacter species.

Simultaneous nutrition removal and high-efficiency biomass and lipid accumulation by microalgae using anaerobic digested effluent from cattle manure combined with municipal wastewater

BACKGROUND

Microalgae as a viable biodiesel feedstock show great potential to approach the challenges of energy shortage and environment pollution, but their economic feasibility was seriously hampered by high production cost. Thus, it is in urgent need to reduce the cost of cultivation and improve the biomass and lipid production of microalgae. In this work, anaerobic digestion effluent from cattle manure combined with municipal wastewater was used as a cost-effective medium for cultivating microalgae and expected to obtain high biomass. The pretreatment of anaerobic digested effluent containing dilution rate, sterilization and nutrient optimization was investigated. Then, initial pH and light intensity for algal growth, lipid production and wastewater purification were optimized in this study.

RESULTS

Scenedesmus sp. could grow rapidly in 10% anaerobic digestion effluent from cattle manure combined with secondary sedimentation tank effluent without sterilization. Optimum nutrient additives for higher biomass were as follows: glucose 10 g/L, NaNO₃ 0.3 g/L, K₂HPO₄·3H₂O 0.01 g/L, MgSO₄·7H₂O 0.075 g/L and trace element A5 solution 1 mL/L. Biomass of 4.65 g/L and lipid productivity of 81.90 mg/L/day were achieved during 7-day cultivation accompanying over 90% of COD, NO₃ ^--N, NH₄ ⁺-N, and 79-88% of PO₄ ^3--P removal with optimized initial pH of 7.0 and light intensity of 5000 l×. The FAME profile in ADEC growth medium consisted in saturated (39.48%) and monounsaturated (60.52%) fatty acids with the 16- to 18-chain-length fatty acids constituting over 98% of total FAME.

CONCLUSIONS

This study proves the potential of anaerobic digested effluent combined with municipal wastewater for microalgae culture, and provides an effective avenue for simultaneous microalgal lipid production and treatment of two kinds of wastewater.