Biochemical Engineering Journal最新文献

Low sugar prices present a significant challenge to the global sugarcane industry, prompting the exploration of diversification strategies for expanding product portfolios. Techno-economic analyses and environmental sustainability assessments were carried out to evaluate the microbial production of tryptophan, erythritol, and collagen from A-molasses in a biorefinery annexed to an existing sugarcane mill. Tryptophan production exhibited the highest profitability, with a minimum selling price (MSP) at 59.7 % of its current market price, although the achievable production volumes of tryptophan from one sugar mill would oversupply the global market. Due to the larger market size of for collagen the achievable production capacity in the collagen scenario would avoid market saturation, reducing the risk of oversupply and rendering it more economically viable. In contrast, erythritol production was marginally not profitable, with an MSP exceeding the current market price by 1 %, primarily attributed to high operational costs. All scenarios demonstrated relatively low greenhouse gas (GHG) emissions (ranging from 9.1 to 16.5 kg CO2eq/kg product), with tryptophan production emerging as the most environmentally favourable option due to minimal chemical and freshwater usage. When compared with literature-reported data on ethanol and short-chain fructooligosaccharides (scFOS), only collagen and ethanol production were deemed viable, based on their favourable profitability and contribution to the market.

Owing to high production cost and low reaction yield, immobilized lipase is rarely used in industrial glycerolysis. This research characterizes the performance of lipase immobilized on rice husk in glycerolysis reaction. By utilizing hexamethylenediamine (HMDA) and glutaraldehyde (GA) as coupling agents, lipase from Thermomyces lanuginosus was immobilized on oxidized rice husk (ORH). For comparison, another sample was prepared where the lipase was directly immobilized on ORH without the use of HMDA and GA. Then, monoglyceride production was performed via glycerolysis using the immobilized lipase. The FTIR analysis verify interactions on rice husk including rice husk oxidation, HMDA coupling, GA activation and lipase immobilization on rice husk. The study found that within the examined range of added lipase for immobilization (10–40 mg-protein/g-support), ORH–HMDA–GA–Lipase possessed superior outcomes in terms of protein loading, immobilization yield, and recovered glycerolysis activity compared to ORH–Lipase. Besides, ORH–HMDA–GA–Lipase exhibits better storage stability (60°C, 44.9 %) and higher reusability (90.0 % monoglyceride yield at the 8th cycle) against ORH–Lipase. The results confirm satisfying performance of the prepared immobilized lipase in glycerolysis and highlight its enhancements facilitated by coupling agents.

The remediation of heavy metal Pb²⁺-contaminated soil by enzyme (urease)-induced calcium carbonate precipitation (EICP) combined with biochar was studied. The solidification efficiency of Pb²⁺ reached 98.41 % when the mass ratio of CaCl₂/urea was 1:1 using EICP technology to remedy Pb²⁺-contaminated water. However, the formed precipitate was accompanied by unstable vaterite, and Pb²⁺ had the risk of secondary leaching. When the biochar of 5 wt% was added to the Pb²⁺-contaminated soil, the soil structure tended to be dense and the toxic leaching concentration of Pb²⁺ was less than 5 mg/L, which met the national standard of China. The addition of biochar increased the pH of the contaminated soil and changed the free Pb²⁺ into insoluble Pb(OH)₂. The biochar provided more nucleation sites for urease, and part of Pb²⁺ were adsorbed on its surface or diffused into the pores of biochar, which effectively solidified Pb²⁺ in the soil.

Cortisol, the primary glucocorticoid in humans, plays crucial physiological functions and serves as an intermediate for synthesizing other glucocorticoids. Currently, cortisol production mainly relies on a semi-synthetic route, where the key step of introducing 11β-OH into 11-deoxycortisol is catalyzed by the filamentous fungi Curvularia lunata and Absidia orchidis. This method, however, generates by-products and involves lengthy cultivation. To achieve specific and efficient production of cortisol, we constructed a recombinant biocatalyst by expressing and engineering the human mitochondrial 11β-hydroxylase CYP11B1 in Escherichia coli. Firstly, the balance between CYP11B1 and its redox partners AdR and Adx was regulated through ribosome binding site (RBS) engineering, resulting in a slight increase in cortisol productivity (from 344±19 mg·L⁻¹·d⁻¹ to 407±7 mg·L⁻¹·d⁻¹). Subsequently, the heterologous expression of CYP11B1 was improved through application of the computational design tool PROSS, generating a triple mutant S169V/H354D/L463F with 87.5 % higher cortisol yield than the wild type. Finally, the catalytic performance was improved by optimizing the recombinant protein expression conditions and enhancing the substrate solubility in the reaction system, further elevating the productivity of cortisol to 2.8±0.1 g·L⁻¹·d⁻¹. To our knowledge, this is the highest ever reported cortisol productivity using a human 11β-hydroxylase-based biocatalyst.

Plasma fractionation stands as a pivotal process for the production of therapeutic and diagnostic proteins, such as albumin and immunoglobulin G. Besides these two primary proteins in human plasma, numerous other proteins can be purified for therapeutic purposes. To support process development, a flowsheet modeling-based approach is utilized to improve production efficiency and productivity while minimizing the resource investments. The flowsheet model is first built to represent the baseline drug substance production process at pilot-scale, with operating parameters extrapolated from lab-scale experiments conducted at CSL Behring. To improve operational efficiency and save costs, throughput analysis is applied to enhance the batch throughput through new process design, scheduling, and bottleneck identification. Through implementing the strategies, the batch throughput could be increased by 47.2 % by introducing one additional operator and one buffer preparation tank into the process. Furthermore, after applying a new strategy involving multiple extractions of the initial material (paste), the batch throughput was doubled, with operating cost of goods reduced by 36.1 %. To assess the performance of the modified design and validate the model results, the pilot-scale experiments with two extractions were performed by CSL Behring and compared with model predictions, resulting in good agreement. This work demonstrates the potential of flowsheet modeling in facilitating process development from lab-scale to pilot-scale, fostering cost-effective and efficient production with limited resource investment.

The polyhydroxyalkanoate terpolymer, P[(3HB)-co-(3HV)-co-(4HB)], is a promising plastic alternative for specialized applications, notably in medical and pharmaceutical sectors. Haloferax mediterranei (Hfx), an extreme halophile archaeon, is a P[(3HB)-co-(3HV)-co-(4HB)] terpolymer production host, however the native molar proportion of 4HB incorporated into the terpolymer is low. To improve incorporation, four 4-hydroxybutyrate-CoA transferases/synthetases from Clostridum kluyveri (OrfZ), Clostridium aminobutyricum (AbfT), Nitrosopumilis maritimus (NmCAT), and Cupriavidus necator N-1 (CnCAT), were heterologously expressed in H. mediterranei, and evaluated for their ability to supply 4HB-CoA for PHA terpolymer production. Growth, PHA synthesis, and polymer composition were evaluated for the four heterologous strains in shake-flask, with Hfx_NmCAT demonstrating superior growth, terpolymer titre and 4HB molar ratio. Co-feeding with γ-butyrolactone was optimised, and Hfx_NmCAT was further evaluated under fed-batch fermentation where a maximum PHA titre of 0.7 g/L, containing 52 mol% 4HB, was achieved. This is an order of magnitude improvement in 4HB terpolymer incorporation by H. mediterranei.

Phospholipase D (PLD) is essential for the bioconversion of phosphatidylcholine (PC) to phosphatidylserine (PS), a process valuable in functional food and medicine. This study explores the stability and catalytic properties of PLD immobilized on chitosan-encapsulated magnetic nanoparticles (CMNPs), utilizing oxidized dextran (DX) and glutaraldehyde (Glu) as cross-linkers. The cross-linker concentration and immobilization time were optimized to assess their effects on PLD catalytic performance. PLD immobilized on CMNPs with DX (DX-CMNPs-PLD) exhibited optimal activity at pH 8.0 and 30 °C, retaining over 40 % activity after 14 cycles, while Glu-cross-linked PLD (Glu-CMNPs-PLD) retained approximately 65 %. DX-CMNPs-PLD demonstrated superior pH, temperature, and operational stability compared to free PLD. Additionally, the immobilized PLD was characterized using transmission electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. Kinetics parameters (V_max and K_m) of the immobilized PLD were also studied with free PLD serving as a control. Conformational analyses indicated a significant change in PLD's secondary structure, particularly in β-sheet content, which likely contributed to the enhanced stability and activity. These findings suggest a promising approach for PLD immobilization on CMNPs, with notable implications for biotechnological applications.