Culturing rhodotorula glutinis in fermentation-friendly deep eutectic solvent extraction liquor of lignin for producing microbial lipid

Optimizing 3D printing and post-processing with sustainable bio-based inks: A comparative study on formulations enriched with brewer's spent grain protein, oleaginous yeast and soy protein isolate

Brewer's spent grain (BSG), a major by-product of the brewing industry, was utilized to produce brewer's spent grain protein (BSGP) and cellulose hydrolysate, the latter of which was subsequently used as a substrate for the fermentation of Rhodotorula glutinis to obtain Rhodotorula glutinis powder (RGP). By optimizing 3D printing ink formulations based on BSGP, RGP, and soy protein isolate (SPI), the rheological properties, 3D printing performance, and post-processing capabilities of the inks were investigated to develop a bio-based ink suitable for 3D printing with balanced nutritional composition and desirable bioactivity. Results of physicochemical characterization further elucidate the interaction mechanisms among the internal components of the inks. Compared to the control group, the addition of RGP reduced the storage modulus and apparent viscosity of Ink-A, which moderately improved the 3D printing performance but resulted in poor mechanical strength of the printed products. With the incremental addition of BSGP, the hydrogen bonding interactions within the composite inks containing BSGP, RGP, and SPI were strengthened, effectively limiting the free movement of internal water molecules. Consequently, the rheological properties of Ink-B, Ink-C, Ink-D, and Ink-E were significantly enhanced, leading to varying degrees of improvement in the 3D printing performance. Notably, Ink-D with a 30 % BSGP content exhibited balanced textural and rheological properties, enabling the production of 3D-printed products with high printing precision. Moreover, the printed products from Ink-D maintained excellent dimensional stability and strong antioxidant activity after steam heating treatment.

Lignocellulose-Derived Energy Materials and Chemicals: A Review on Synthesis Pathways and Machine Learning Applications

Lignocellulose biomass, Earth's most abundant renewable resource, is crucial for sustainable production of high-value chemicals and bioengineered materials, especially for energy storage. Efficient pretreatment is vital to boost lignocellulose conversion to bioenergy and biomaterials, cut costs, and broaden its energy-sector applications. Machine learning (ML) has become a key tool in this field, optimizing pretreatment processes, improving decision-making, and driving innovation in lignocellulose valorization for energy storage. This review explores main pretreatment strategies - physical, chemical, physicochemical, biological, and integrated methods - evaluating their pros and cons for energy storage. It also stresses ML's role in refining these processes, supported by case studies showing its effectiveness. The review examines challenges and opportunities of integrating ML into lignocellulose pretreatment for energy storage, underlining pretreatment's importance in unlocking lignocellulose's full potential. By blending process knowledge with advanced computational techniques, this work aims to spur progress toward a sustainable, circular bioeconomy, particularly in energy storage solutions.

Valorization of wheat straw through enhancement of cellulose accessibility, xylan elimination and lignin removal by choline chloride:p-toluenesulfonic acid pretreatment

Different molar ratio of choline chloride (ChCl) and p-toluenesulfonic acid (p-TsOH) (2:1, 1:1 and 1:2, mol:mol) were used to prepare deep eutectic solvents (ChCl:p-TsOH) for pretreating cellulose fibers to elevate cellulose accessibility, enhance xylan elimination, increase lignin removal and promote enzymatic digestion. ChCl:p-TsOH (1:1, mol:mol) could effectually destroy the dense layout of wheat straw (WS) at 80 °C for 60 min. Cellulose crystallinity declined from 43.4 % to 25.5 %, and the lignin surface area and hydrophobicity were reduced to 182.6 m2/g and 3.2 L/g, respectively. While cellulose accessibility in WS was significantly improved to 523.9 mg/g. The delignification and xylan removal reached 72.4 % and 90.5 %, respectively. The enzymatic digestibility reached 89.3 %. Furthermore, molecular dynamics simulation and quantum chemistry calculation were conducted on the lignocellulose model. The van der Waals interaction between ChCl:p-TsOH and lignin and the dispersion interaction between ChCl and lignin were identified. Accordingly, the interaction between biomass and ChCl:p-TsOH was elucidated at the molecular level. It provided a comprehensive understanding of lignocellulosic biomass valorization through the highly efficient pretreatment by ChCl:p-TsOH.

One-pot green and sustainable process for the biotransformation of sophoricoside to genistein from Fructus Sophorae with magnetic cellulose spheres immobilized Aspergillus oryzae on cellulose using deep eutectic solvent assisted

This study introduces a green, sustainable, and efficient approach for biotransforming sophoricoside into genistein from Fructus Sophorae using Aspergillus oryzae by removal of one molecule of glucose by β-glucosidase, an edible microorganism immobilized on magnetic cellulose and treated with deep eutectic solvents (DES). The goal was to enhance the biotransformation ratio by optimizing reaction conditions and selecting the most suitable DES. Various DESs, including natural deep eutectic solvents (NADES), were assessed for their ability to improve catalytic performance. Among them, the NADES system comprising choline chloride (CHCL) and glycerol (G) exhibited the highest catalytic efficiency (32.19 mg/g) under optimal conditions: temperature 33 °C, time 65 hours, pH 5.5, and a liquid-to-solid ratio of 45:1 (mL/g). This yield was 10.60 times greater than the genistein yield from untreated F. Sophorae. This combination notably increased cell membrane permeability, aiding the bioconversion process. The cellulose immobilization technique provided a stable and reusable microreactor and maintained microbial activity (80.37%) over 10 cycles. These findings validate the bioconversion method as a promising and sustainable strategy for genistein production from plant-derived sophoricoside, with potential applications in pharmaceutical and nutraceutical industries.

Current upstream and downstream process strategies for sustainable yeast lipid production

An increasing global population demands more lipids for food and chemicals, but the unsustainable growth of plant-derived lipid production and an unreliable supply of certain lipids due to environmental changes, require new solutions. One promising solution is the use of lipids derived from microbial biomass, particularly oleaginous yeasts. This critical review begins with a description of the most promising yeast lipid replacement targets: palm oil substitute, cocoa butter equivalent, polyunsaturated fatty acid source, and animal fat analogue, emphasizing sustainability aspects. Subsequently, the review focuses on the most recent advances in upstream methodologies, particularly fermentation strategies that promote circularity, such as waste valorisation, co-cultivation and co-product biosynthesis. Downstream processing methods for minimising energy consumption and waste generation, including bioflocculation, energy-efficient and environmentally friendly cell lysis and extraction, and integrated co-product recovery methods, are discussed. Finally, the current challenges are outlined. Integrating these strategies advances sustainable yeast lipid production for high-value applications.

Bioconversion of Shrimp Waste into Functional Lipid by a New Oleaginous Sakaguchia sp

Chitin, the second most abundant biomolecule after cellulose in nature, is a significant aquaculture by-product, and is estimated at 6-8 million tons annually. Chitin is composed of monomeric N-acetylglucosamine (NAG) which can be seen as an alternative feedstock for biotechnology. Microbial functional lipids have gained attention due to their bioactivity and sustainable production. In this study, a new oleaginous yeast strain named Sakaguchia sp. HKC2 was found to be able to use NAG as the carbon source for growth and accumulate functional lipids such as PUFAs and carotenoids. When cultured on the NAG-containing medium, strain HKC2 exhibited slower growth and slower intracellular lipid accumulation compared to those on a glucose-containing medium. However, the lipids obtained from HKC2 grown on NAG medium were richer in PUFAs. Notably, torularhodin-a powerful bioactive carotenoid-was found in all HKC2 cultures on NAG, while torulene was abundant in glucose medium. These findings highlight a novel avenue for utilizing aquatic by-products and unlocking their potential.

Microbial Valorization of Lignin to Bioplastic by Genome-Reduced Pseudomonas putida

As the most abundant natural aromatic resource, lignin valorization will contribute to a feasible biobased economy. Recently, biological lignin valorization has been advocated since ligninolytic microbes possess proficient funneling pathways of lignin to valuable products. In the present study, the potential to convert an actual lignin stream into polyhydroxyalkanoates (PHAs) had been evaluated using ligninolytic genome-reduced Pseudomonas putida. The results showed that the genome-reduced P. putida can grow well on an actual lignin stream to successfully yield a high PHA content and titer. The designed fermentation strategy almost eliminated the substrate effects of lignin on PHA accumulation. Employing a fed-batch strategy produced the comparable PHA contents and titers of 0.35 g/g dried cells and 1.4 g/L, respectively. The molecular mechanism analysis unveiled that P. putida consumed more small and hydrophilic lignin molecules to stimulate cell growth and PHA accumulation. Overall, the genome-reduced P. putida exhibited a superior capacity of lignin bioconversion and promote PHA accumulation, providing a promising route for sustainable lignin valorization.

Recent Biotechnology Advances in Bio-Conversion of Lignin to Lipids by Bacterial Cultures

The complexity and recalcitrance of the lignin structure is a major barrier to its efficient utilization and commercial production of high-value products. In recent years, the “bio-funneling” transformation ability of microorganisms has provided a significant opportunity for lignin conversion and integrated biorefinery. Based on the chemical structure of lignin, this mini-review introduces the recent advances of lignin depolymerization by bacterial strains and the application of microbial lignin degradation in lipids production. Furthermore, the current challenges, future trends and perspectives for microbe-based lignin conversion to lipids are discussed.

Controlling the Formation of Foams in Broth to Promote the Co-Production of Microbial Oil and Exopolysaccharide in Fed-Batch Fermentation

A large amount of foam is generated in the production of microbial oil and exopolysaccharide (EPS) by Sporidiobolus pararoseus JD-2, which causes low efficiency in fermentation. In this study, we aimed to reduce the negative effects of foams on the co-production of oil and EPS by controlling the formation of foams in broth. As we have found, the formation of foams is positively associated with cell growth state, air entrapment, and properties of broth. The efficient foam-control method of adding 0.03% (v/v) of the emulsified polyoxyethylene polyoxypropylene pentaerythritol ether (PPE) and feeding corn steep liquor (CSL) at 8–24 h with speed of 0.02 L/h considerably improved the fermentation performance of S. pararoseus JD-2, and significantly increased the oil and EPS concentrations by 8.7% and 12.9%, respectively. The biomass, oil, and EPS concentrations were further increased using a foam backflow device combined with adding 0.03% (v/v) of the emulsified PPE and feeding CSL at 8–24 h, which reached to 62.3 ± 1.8 g/L, 31.2 ± 0.8 g/L, and 10.9 ± 0.4 g/L, respectively. The effective strategy for controlling the formation of foams in fermentation broth reported here could be used as a technical reference for producing frothing products in fed-batch fermentation.

Recent advances of lignin valorization techniques toward sustainable aromatics and potential benchmarks to fossil refinery products

Aromatic compounds are important fuels and key chemical precursors for organic synthesis, however the current aromatics market are mainly relying on fossil resources which will eventually contribute to carbon emissions. Lignin has been recognized as a drop-in substitution to conventional aromatics, with its values gradually realized after tremendous research efforts in the recent five years. To facilitate the development of a possible lignin economics, this study overviewed the recent advances of various biorefinery techniques and the remaining challenging for lignin valorization. Starting with recent discovery of unexplored lignin structures, the potential functions of lignin related chemical structures were emphasized. The important breakthrough of lignin-first pretreatment, catalytic lignin depolymerization, and the high value products with possible benchmark with modern aromatics were reviewed with possible future targets. Possible retrofit of conventional petroleum refinery for lignin products were also introduced and hopefully paving a way to progressively migrate the industry towards carbon neutrality.