Microbial lipid production from soybean hulls using Lipomyces starkeyi LPB53 in a circular economy

Boosting biodegradation and mineralization efficiencies of chlorinated VOCs: The synergy of H2O2 and biotrickling filtration

This study explores a new biodegradation process of H2O2-stimulated BTFs to remove perchloroethylene (PCE) from the contaminated air stream. BTF stimulated with H2O2 significantly boosted PCE biodegradation compared to conventional methods. Optimal parameters for H2O2-assisted PCE biodegradation were also identified (nominal inlet concentration = 150 ppm, EBCT = 30 s, H2O2/PCE molar ratio = 0.2). Under these optimum conditions, the BTF achieved a maximum PCE removal efficiency of around 95 %, a mineralization rate of 65 %, and an elimination capacity of 117 g/m3.h, demonstrating its effectiveness. The BTF maintained stable performance under various PCE loads, suggesting its applicability for industrial cases. Moreover, the study revealed a positive correlation between increasing H2O2/PCE ratios and the activities of key enzymes responsible for biodegradation including dehydrogenase)increased from 1.3 to 26.1 mg-TF/gbiomass), peroxidase (increased from 0 to 251 U/gbiomass), and catalase (increased from 0 to 7.8 U/gbiomass) when the ratio was increased from 0 to 0.2. The H2O2-stimulated BTF performed efficiently for biodegradation (>90 %) and mineralization (>60 %) of PCE at empty bed contact times between 20 and 60 s. Finally, the absence of PCE and toxic intermediates in the recycled liquid supports the efficient biodegradation of PCE in the developed system. In conclusion, H2O2-stimulated BTF shows promise as a sustainable and cost-effective approach for biodegradation of chlorinated organic compounds in contaminated air streams.

Sustainable lipid production by oleaginous yeasts: Current outlook and challenges

Yeast lipid has gained prominence as a sustainable energy source and so various oleaginous yeasts are being investigated to create efficient lipogenic platforms. This review aims to assess the various biotechnological strategies for enhanced production of yeast lipids via agro-waste processing and media engineering including multiomic analyses, genetic engineering, random mutagenesis, and laboratory adaptive evolution. The review also emphasizes the role of cutting-edge omics technologies in pinpointing differentially expressed genes and enriched networks crucial for designing advanced metabolic engineering strategies for prominent oleaginous yeast species. The review addresses the challenges and future prospects of a viable lipid production industry that is possible through advancements in current technologies, strain improvement, media optimization and techno-economic and life cycle analyses at lab, pilot and industrial scales. This review comprehensively provides deep insights for enhancement of yeast lipid biosynthesis to reach industrially benchmarked standard of a lipid production platform.

Microbial conversion of Limonene-containing waste into transesterifiable bio-lipids: Evaluating oleaginous bacterial isolates

Bio-oil is increasingly recognized as a sustainable and eco-friendly energy source, offering a viable alternative to petro-diesel. This study evaluates the bio-oil production potential of a novel oleaginous strain, KM9 (Serratia surfactantfaciens YD25) compared with the known oleaginous species R. erythropolis. Growth conditions and nutrient requirements were optimized for both strains to maximize biomass production and lipid accumulation. Utilizing orange waste as a substrate not only contributes to waste minimization but also provides a renewable carbon source for microbial lipid synthesis. KM9 demonstrated exceptional performance, achieving 50% reduction in organic matter from the orange waste while simultaneously accumulating lipids upto 38% of its dry cell weight. Gas chromatography-mass spectrometry (GC-MS) analysis of the transesterified lipids revealed that both KM9 and R. erythropoliss produced comparable levels of saturated fatty acids (38.39% and 39%, respectively), when cultivated in limonene-modified media. Notably, the use of orange waste stimulated the production of monounsaturated fatty acids (MUFAs), particularly palmitic and stearic acids, resulting in a lipid profile closely resembling that of plant-based bio-oils. These findings highlight the promising potential of the oleaginous strain KM9 for producing microbial lipids from orange waste, contributing to sustainable biodiesel production and effectively valorizing a significant agricultural waste stream.

Ternary removal of Zn, Ni, and Mn from metal industry wastewater using soybean hulls as adsorbents

With the growth of the metalworking industry, effective control of wastewater with phosphate has become a global concern. This study took advantage of the abundant supply of natural soybean hulls as an adsorbent for the direct treatment of wastewater, aiming to remove Ni, Zn, and Mn from real wastewater produced during the phosphating stage of the metalworking industry to address this issue. Soybean hulls presented a specific surface area of 0.31 m2 g-1, average diameter of 0.2705 mm, and a pH value for PCZ of 6.43 at 25 °C. Real wastewater was acidic (pH 3.68) with COD of 1270 mg L-1 and highly concentrated in Ni, Mn, and Zn (343.45 mg L-1, 818.6 mg L-1, and 953.85 mg L-1, respectively). It was observed that the process depended on the adsorbent dosage, which can be linked to the low surface area of the material. The optimized pH value was found to be the natural pH of the effluent, which varied between 3 and 4. The average removal rates were 24.5% for Ni, 28.6% for Zn, and 16.5% for Mn, corresponding to the respective removal of 84.15, 135.07, and 272.80 mg L-1 in a ternary system. The maximum adsorption capacities were observed at 50 °C, estimated as 3.125 mg g-1 for Ni, 14.128 mg g-1 for Zn, and 7.8 mg g-1 for Mn. When evaluating the process kinetics, it was observed that adsorption capacity increased significantly during the initial 60 min, followed by a slower rate until saturation. The pseudo-first-order model provided the best fit for Ni adsorption, while Zn and Mn demonstrated the best fit with the pseudo-second-order model. This trend possibly occurred due to the different initial concentrations of each metal, which has shown to be a key factor in mass-driven adsorption mechanisms. Thus, using raw soybean hulls can be considered a viable alternative for coupling adsorption as a low-cost step to other treatment methods for metalworking wastewater.

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.