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.