Second- and third-generation biodiesel production with immobilised recombinant Rhizopus oryzae lipase: Influence of the support, substrate acidity and bioprocess scale-up

Nano-based biofuel production from low-cost lignocellulose biomass: environmental sustainability and economic approach

The use of nanomaterials in biofuel production from lignocellulosic biomass offers a promising approach to simultaneously address environmental sustainability and economic viability. This review provides an overview of the environmental and economic implications of integrating nanotechnology into biofuel production from low-cost lignocellulosic biomass. In this review, we highlight the potential benefits and challenges of nano-based biofuel production. Nanomaterials provide opportunities to improve feedstock pretreatment, enzymatic hydrolysis, fermentation, and catalysis, resulting in enhanced process efficiency, lower energy consumption, and reduced environmental impact. Conducting life cycle assessments is crucial for evaluating the overall environmental footprint of biofuel production. An economic perspective that focuses on the cost implications of utilizing nanomaterials in biofuel production is also discussed. A comprehensive understanding of both environmental and economic dimensions is essential to fully harness the potential of nanomaterials in biofuel production from lignocellulosic biomass and to move towards sustainable future energy.

Recent Advances in Overexpression of Functional Recombinant Lipases

Heterologous functional expression of the recombinant lipases is typically a bottleneck due to the expression in the insoluble fraction as inclusion bodies (IBs) which are in inactive form. Due to the importance of lipases in various industrial applications, many investigations have been conducted to discover suitable approaches to obtain functional lipase or increase the expressed yield in the soluble fraction. The utilization of the appropriate prokaryotic and eukaryotic expression systems, along with the suitable vectors, promoters, and tags, has been recognized as a practical approach. One of the most powerful strategies to produce bioactive lipases is using the molecular chaperones co-expressed along with the target protein's genes into the expression host to produce the lipase in soluble fraction as a bioactive form. The refolding of expressed lipase from IBs (inactive) is another practical strategy which is usually carried out through chemical and physical methods. Based on recent investigations, the current review simultaneously highlights strategies to express the bioactive lipases and recover the bioactive lipases from the IBs in insoluble form.

Trends in the Use of Lipases: A Systematic Review and Bibliometric Analysis

Scientific mapping using bibliometric data network analysis was applied to analyze research works related to lipases and their industrial applications, evaluating the current state of research, challenges, and opportunities in the use of these biocatalysts, based on the evaluation of a large number of publications on the topic, allowing a comprehensive systematic data analysis, which had not yet been conducted in relation to studies specifically covering lipases and their industrial applications. Thus, studies involving lipase enzymes published from 2018 to 2022 were accessed from the Web of Science database. The extracted records result in the analysis of terms of bibliographic compatibility among the articles, co-occurrence of keywords, and co-citation of journals using the VOSviewer algorithm in the construction of bibliometric maps. This systematic review analysis of 357 documents, including original and review articles, revealed studies inspired by lipase enzymes in the research period, showing that the development of research, together with different areas of knowledge, presents good results related to the applications of lipases, due to information synchronization. Furthermore, this review showed the main challenges in lipase applications regarding increased production and operational stability; establishing well-defined evaluation criteria, such as cultivation conditions, activity, biocatalyst stability, type of support and reactor; thermodynamic studies; reuse cycles; and it can assist in defining goals for the development of successful large-scale applications, showing several points for improvement of future studies on lipase enzymes.

Microbial assemblage for solid waste bioremediation and valorization with an essence of bioengineering

Environmental solid waste bioremediation is a method of treating contaminated solid waste that involves changing ecological conditions to foster the growth of a broad spectrum of microorganisms and the destruction of the target contaminants. A wide range of microorganisms creates metabolites that may break down and change solid waste-based pollution to various value-added molecules. Diverse bioremediation technologies, their limitations, and the procedure involve recycling solid waste materials from the environment. The existing environmental solid waste disposal services are insufficient and must be upgraded with more lucrative recovery, recycling, and reuse technologies to decrease the enormous expenditures in treatment procedures. Bioremediation of solid waste eliminates the toxic components. It restores the site with the advent of potential microbial communities towards solid waste valorization utilizing agriculture solid waste, organic food waste, plastic solid waste, and multiple industrial solid wastes.Bioengineering on diverse ranges of microbial regimes has accelerated to provide extra momentum toward solid waste recycling and valorization. This approach increases the activity of bioremediating microbes in the commercial development of waste treatment techniques and increases the cost-effective valuable product generation. This framework facilitates collaboration between solid waste and utilities. It can aid in establishing a long-term management strategy for recycling development with the advent of a broad spectrum of potential microbial assemblages, increasing solid waste contamination tolerance efficiency and solid waste degradability. The current literature survey extensively summarises solid waste remediation valorization using a broad spectrum of microbial assemblages with special emphasis on bioengineering-based acceleration. This approach is to attain sustainable environmental management and value-added biomolecule generation.

Utilization of Polymeric Materials toward Sustainable Biodiesel Industry: A Recent Review

The biodiesel industry is expanding rapidly in accordance with the high energy demand and environmental deterioration related to the combustion of fossil fuel. However, poor physicochemical properties and the malperformance of biodiesel fuel still concern the researchers. In this flow, polymers were introduced in biodiesel industry to overcome such drawbacks. This paper reviewed the current utilizations of polymers in biodiesel industry. Hence, four utilizing approaches were discussed, namely polymeric biodiesel, polymeric catalysts, cold-flow improvers (CFIs), and stabilized exposure materials. Hydroxyalkanoates methyl ester (HAME) and hydroxybutyrate methyl ester (HBME) are known as polymeric biodiesel sourced from carbon-enriched polymers with the help of microbial activity. Based on the literature, the highest HBME yield was 70.7% obtained at 10% H2SO4 ratio in methanol, 67 °C, and 50 h. With increasing time to 60 h, HAME highest yield was reported as 68%. In addition, polymers offer wide range of esterification/transesterification catalysts. Based on the source, this review classified polymeric catalysts as chemically, naturally, and waste derived polymeric catalysts. Those catalysts proved efficiency, non-toxicity, economic feasibility, and reusability till the 10th cycle for some polymeric composites. Besides catalysis, polymers proved efficiency to enhance the biodiesel flow-properties. The best effect reported in this review was an 11 °C reduction for the pour point (PP) of canola biodiesel at 1 wt% of ethylene/vinyl acetate copolymers and cold filter plugging point (CFPP) of B20 waste oil biodiesel at 0.08 wt% of EVA copolymer. Polymeric CFIs have the capability to modify biodiesel agglomeration and facilitate flowing. Lastly, polymers are utilized for storage tanks and auto parts products in direct contact with biodiesel. This approach is completely exclusive for polymers that showed stability toward biodiesel exposure, such as polyoxymethylene (POM) that showed insignificant change during static immersion test for 98 days at 55 °C. Indeed, the introduction of polymers has expanded in the biodiesel industry to promote green chemistry.

Kinetic and thermodynamic study of enzymatic hydroesterification mechanism to fatty acid methyl esters synthesis

Eversa® Transform 2.0 lipase used as biocatalyst to biodiesel (fatty acid methyl esters - FAME) synthesis has been the target of interesting studies due to its thermostability and cost-effectiveness. In these researches, data about reaction conditions that result in satisfactory yields were investigated. Nevertheless, kinetic and thermodynamic parameters considering this enzyme are scarce. This paper presents an estimation of kinetic and thermodynamic parameters for the Eversa® Transform 2.0-mediated hydroesterification to FAME synthesis. Kinetic studies were performed for different methanol, water and lipase loads in distinct temperatures. Parameters adjusted by the thermodynamic model indicate that the hydrolysis is decisive in the overall hydroesterification reaction rate and the esterification reaction is endothermic (ΔH_e = 38.98 kJ/mol). Formation of enzymatic complexes is favored by increasing the temperature, especially the enzyme-methanol inhibition complex. Statistical analysis showed that the model was not overparameterized, and the small confidence interval indicated good reliability of the estimated parameters.

Producing Natural Flavours from Isoamyl Alcohol and Fusel Oil by Using Immobilised Rhizopus oryzae Lipase

Enzymatic synthesis of short-chain esters (flavours) might enable their labelling as natural, increasing their value. Covalently immobilised Rhizopus oryzae lipase (EO-proROL) was used to synthesise isoamyl butyrate and acetate. In cyclohexane, the best performer reaction solvent, 1.8 times higher yield of isoamyl butyrate (ca. 100%) than isoamyl acetate (ca. 55%) was obtained. Optimum initial acid concentration (410 mM) and acid:alcohol mole ratio (0.5) were established by a central composite rotatable design to maximise isoamyl butyrate single-batch and cumulative production with reused enzyme. These conditions were used to scale up the esterification (150 mL) and to assess yield, initial esterification rate, productivity and enzyme operational stability. Commercial isoamyl alcohol and fusel oil results were found to be similar as regards yield (91% vs. 84%), initial reaction rate (5.4 µM min−1 with both substrates), operational stability (40% activity loss after five runs with both) and productivity (31.09 vs. 28.7 mM h−1). EO-proROL specificity for the structural isomers of isoamyl alcohol was also evaluated. Thus, a successful biocatalyst and product conditions ready to be used for isoamyl ester industrial production are here proposed.

Bioprocesses for the Biodiesel Production from Waste Oils and Valorization of Glycerol

The environmental context causes the use of renewable energy to increase, with the aim of finding alternatives to fossil-based products such as fuels. Biodiesel, an alternative to diesel, is now a well-developed solution, and its production from renewable resources makes it perfectly suitable in the environmental context. In addition, it is biodegradable, non-toxic and has low greenhouse gas emissions: reduced about 85% compared to diesel. However, the feedstock used to produce biodiesel competes with agriculture and the application of chemical reactions is not advantageous with a “green” process. Therefore, this review focuses only on bioprocesses currently taking an important place in the production of biodiesel and allow high yields, above 90%, and with very few produced impurities. In addition, the use of waste oils as feedstock, which now accounts for 10% of feedstocks used in the production of biodiesel, avoids competition with agriculture. To present a complete life-cycle of oils in this review, a second part will focus on the valorization of the biodiesel by-product, glycerol. About 10% of glycerol is generated during the production of biodiesel, so it should be recovered to high value-added products, always based on bioprocesses. This review will also present existing techniques to extract and purify glycerol. In the end, from the collection of feedstocks to the production of CO2 during the combustion of biodiesel, this review presents the steps using the “greener” possible processes.

Improvement of methanol tolerance and catalytic activity of Rhizomucor miehei lipase for one-step synthesis of biodiesel by semi-rational design

Exploiting highly active and methanol-resistant lipase is of great significance for biodiesel production. A semi-rational directed evolution method combined with N-glycosylation is reported, and all mutants exhibiting higher catalytic activity and methanol tolerance than the wild type (WT). Mutant N267 retained 64% activity after incubation in 50% methanol for 8 h, which was 48% greater than that of WT. The catalytic activity of mutants N267 and N167 was 30- and 71- fold higher than that of WT. Molecular dynamics simulations of N267 showed that the formation of new strong hydrogen bonds between glycan and the protein stabilized the structure of lipase and improved its methanol tolerance. N267 achieved biodiesel yields of 99.33% (colza oil) and 81.70% (waste soybean oil) for 24 h, which was much higher than WT (51.6% for rapeseed oil and 44.73% for wasted soybean oil). The engineered ProRML mutant has high potential for commercial biodiesel production.

Integrated bioprocess for structured lipids, emulsifiers and biodiesel production using crude acidic olive pomace oils

Olive pomace oil (OPO), a by-product of olive oil industry, is directly consumed after refining. The novelty of this study consists of the direct use of crude high acidic OPO (3.4-20% acidity) to produce added-value compounds, using sn-1,3-regioselective lipases: (i) low-calorie dietetic structured lipids (SL) containing caprylic (C8:0) or capric (C10:0) acids by acidolysis or interesterification with their ethyl esters, (ii) fatty acid methyl esters (FAME) for biodiesel, and (iii) sn-2 monoacylglycerols (emulsifiers), as by-product of FAME production by methanolysis. Immobilized Rhizomucor miehei lipase showed similar activity in acidolysis and interesterification for SL production (yields: 47.8-53.4%, 7 h, 50℃) and was not affected by OPO acidity. Batch operational stability decreased with OPO acidity, but it was at least three-fold in interesterification that in acidolysis. Complete conversion of OPO into FAME and sn-2 monoacylglycerols was observed after 3 h-transesterification (glycerol stepwise addition) and lipase deactivation was negligeable after 11 cycles.

Constitutive Expression in Komagataella phaffii of Mature Rhizopus oryzae Lipase Jointly with Its Truncated Prosequence Improves Production and the Biocatalyst Operational Stability

Rhizopus oryzae lipase (ROL) containing 28 C-terminal amino acids of the prosequence fused to the N-terminal mature sequence in ROL (proROL) was successfully expressed in the methylotrophic yeast Komagataella phaffii (Pichia pastoris) under the constitutive glyceraldehyde-3-phosphate dehydrogenase promoter (PGAP). Although the sequence encoding the mature lipase (rROL) was also transformed, no clones were obtained after three transformation cycles, which highlights the importance of the truncated prosequence to obtain viable transformed clones. Batch cultures of the K. phaffii strain constitutively expressing proROL scarcely influenced growth rate and exhibited a final activity and volumetric productivity more than six times higher than those obtained with proROL from K. phaffii under the methanol-inducible alcohol oxidase 1 promoter (PAOX1). The previous differences were less marked in fed-batch cultures. N-terminal analysis confirmed the presence of the 28 amino acids in proROL. In addition, immobilized proROL exhibited increased tolerance of organic solvents and an operational stability 0.25 and 3 times higher than that of immobilized rROL in biodiesel and ethyl butyrate production, respectively. Therefore, the truncated prosequence enables constitutive proROL production, boosts bioprocess performance and provides a more stable biocatalyst in two reactions in which lipases are mostly used at industrial level, esterification (ethyl butyrate) and transesterification (biodiesel).