Enzyme Co-Immobilization on Precipitated Silica for Sustainable Lactobionic Acid Production

Efficient synthesis of nicotinic acid by biomimetic mineralization-immobilized whole-cell biocatalysts

Scalable catalyst production process for oleate hydratase whole-cell biocatalysis.

The sustainable production of hydroxy fatty acids, such as 10-hydroxystearic acid (10-HSA), by biocatalysis is a promising alternative to petrochemical and castor oil-derived products. However, industrial implementation still requires an efficient and scalable process for biocatalyst production by fermentation, which precedes the biotransformation to 10-HSA. In general, industrial biocatalysis is commonly performed using whole cells, which are cheaper than purified enzymes. Still, the fermentation process itself is a major cost contributor requiring a high-yielding and scalable process. Here, we established and scaled a lactose-induced fed-batch process to produce an Escherichia coli BL21 (DE3) based whole-cell biocatalyst containing an oleate hydratase from Stenotrophomonas nitritireducens. The two-phased process employs an initial growth phase on glucose, followed by an induced feed phase using glycerol and lactose. When comparing two different growth rates during enzyme expression, a higher growth rate was found beneficial, resulting in a higher biomass concentration of 69.2 ± 0.5 g L-1 and a yield increase of 80 % while maintaining biocatalyst activity at >85 % conversion. This highlights the importance of process design variables, such as growth rate settings, for a high-yielding and economic process. Feasibility of the process was demonstrated by scaling into a 150 L bioreactor, achieving a biomass concentration of 60.6 ± 0.4 g L-1 with a yield of 0.44 gC,Biomass gC -1 and 91.5 ± 1.4 % conversion. Supplemented with an initial test of suitable unit operations for technical biomass separation, this work provides a fermentation route for a whole-cell oleate hydratase biocatalyst, paving the way for further scaling toward industrial 10-HSA production.

Laccase Immobilization on Tannic Acid–Coated Nylon Membrane for Dye Decolorization

Laccase catalyzes the oxidation of a wide array of substrates, yet its industrial applications are hindered by its low thermal and chemical stability, poor reusability, and high production costs. Enzyme immobilization is a cost-effective strategy for overcoming these limitations, enhancing stability and operational efficiency. In this study, laccase from Trametes versicolor (LTV) was immobilized onto a nylon membrane coated with 3-aminopropyltriethoxysilane (APTES) and tannic acid (TA). A mathematical model was employed to optimize enzyme immobilization parameters (e.g., pH, LTV concentration, TA:APTES ratio, and reaction time), resulting in an enzyme loading of 31.9% w/w LTV and immobilization yield of 67.3%. The resulting biocatalytic system was characterized via ATR-FTIR, SEM–EDX, Raman, and fluorescence techniques, and the kinetics of free and immobilized LTV were analyzed. Immobilized LTV successfully oxidized 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) across broad pH (2–9) and temperature (20 °C–70 °C) ranges. Compared to the free enzyme, immobilized LTV demonstrated improved storage stability and catalytic performance. Notably, immobilized LTV successfully decolorized methylene blue and methyl red dyes, validating the utility of this platform for environmental remediation applications.

Immobilization of Kluyveromyces lactis for xylose production using different lignocellulosic materials as carbon sources

Lignocellulosic biowaste is a renewable and abundant resource with significant potential for the production of value-added products such as xylose which is a major intermediary in the biofuel, bioplastic, and pharmaceutical sectors. However, problems such as inefficient bioconversion and instability of free-cell fermentation systems limit its industrial application. This research investigates the use of immobilized recombinant Kluyveromyces lactis for xylose production using various lignocellulosic biowastes such as sugarcane bagasse, corn stover, rice straw, oil palm fronds, and banana leaves. The biowastes were washed, dried, ground, and pre-treated with 1% sodium hydroxide (NaOH) solution. K. lactis cells were cultivated in yeast peptone dextrose (YPD) medium and immobilized in 2% sodium alginate beads cross-linked with 0.1 M calcium chloride (CaCl2). Fermentation was carried out at 30 °C and 150 rpm for 24 hours using 1 g of pre-treated biomass and immobilized yeast beads in 100 mL of YPD medium. Reducing sugar concentration was determined using the dinitro salicylic acid (DNS) method, while yeast growth and pH changes were monitored. Results demonstrated that immobilized K. lactis could produce xylose production across all biowaste types, with sugarcane bagasse and corn stover yielding the highest reducing sugar concentrations. However, a further optimization is needed to increase the enzyme production from the immobilized cell systems. The findings highlight a cost-effective and environmentally friendly approach for improving industrial xylose production through K. lactis immobilization on lignocellulosic biowastes.

Sodium alginate–entrapped laccase from solid-state cultures of Aspergillus oryzae as a promising system for asymmetric degradation of synthetic azo dyes

Sustainable co-production of L-theanine via an integrated biocatalytic system exploiting atrazine degradation.

L-Theanine is a health-beneficial tea-specific amino acid. This amino acid is synthesized through the catalytic action of L-theanine synthase or its isoenzymes, utilizing ethylamine and L-glutamic acid as primary substrates. As the rate-limiting substance, traditional ethylamine synthesis relies on tea root metabolism, and exploring new synthetic pathways can boost L-theanine production and explore environmental application values. Self-developed Tongji_Software was used to predict a potential pathway for ethylamine synthesis. A cell-free protein synthesis (CFPS) system was adopted for verification, and genome engineering was performed to construct a recombinant strain. According to the software predictions, atrazine chlorohydrolase (AtzA) and hydroxyatrazine deethylaminase (AtzB) could convert the herbicide atrazine into ethylamine. CFPS based on Pseudomonas knackmussii (P. knackmussii) produced 88.5 μM L-theanine within a 24-h period, while the engineered strain P. knackmussii-AtzAB yielded 445.7 μM with the conversion rate of 44.6% over 84 h of fermentation. In summary, we revealed a novel pathway for ethylamine synthesis, which can promote L-theanine accumulation in tea trees and degrade environmental pollutants.