Xylitol, a common sugar substitute in food and pharmaceuticals, can be produced microbially using glucose as the primary substrate. Our earlier study established an efficient one-step biotransformation system in Gluconobacter oxydans that converts D-arabitol to xylitol. To improve the reusability of resting cells, recombinant G. oxydans was immobilized in a composite matrix of Cyclotella meneghiniana frustules and solium alginate. The combined approach not only enhanced the mechanical strength and stability of the beads but may also have facilitated oxygen transfer within the immobilization matrix. Compared with frustules adsorption and alginate encapsulation alone, the combined immobilized cells exhibited increases in catalytic activity of 32.8
This study developed and evaluated particulate and spherical cellulosic supports derived from sugarcane bagasse for the oriented immobilization of recombinant enzymes containing a cellulose-binding domain (CBD), using β-galactosidase-CBD (β-Gal-CBD) as a model. The bagasse was subjected to alkaline hydrolysis (L) and sequential acid and alkaline hydrolysis (LH), resulting in supports with progressively higher cellulose contents, as confirmed by chemical analysis, Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The LH treatment yielded the support with the highest cellulosic purity, leading to superior performance in immobilization (LH-Gal). At a loading of 10 U/g, the particulate LH support achieved a recovered activity exceeding 100
In this work a dynamic modeling framework for metabolic systems that combines metabolic graph neural networks (MGNNs) with nonlinear state estimation is developed to address the problems of sparseness and noisiness in bioprocess data. The MGNN architecture embeds known metabolic reaction connectivity into the model structure, restricting information flow to biochemically plausible interactions and reducing the number of trainable parameters relative to fully connected neural networks. To enable the estimation of unmeasured metabolites, the MGNN is coupled with an extended Kalman filter (EKF), which performs recursive state estimation using partial and noisy measurements. The framework is evaluated using two systems with distinct metabolic characteristics: Escherichia coli undergoing diauxic growth and a reduced oxidative stress network for Bordetella pertussis. Across both case studies, the MGNN-EKF observer yields lower estimation error and improved robustness to noise compared with a fully connected neural network under matched training conditions, for spare data scenario. Empirical observability analysis based on Gramian metrics validates the theoretical reconstructability of these states. These results indicate that embedding metabolic structure into data-driven dynamic models and coupling it with a state estimator improves predictions in bioprocess systems with limited measurements.
Lithium refinery residue (LRR), generated during the sulfuric acid processing of spodumene, is dominated by aluminosilicate phases and contains residual lithium (Li). Although bioleaching has been applied to primary Li ores and spent lithium-ion batteries, its applicability to aluminosilicate-dominated LRR remains poorly understood. Here, Acidithiobacillus thiooxidans, Acidithiobacillus ferrooxidans, and a mixed culture of the two species were evaluated for Li bioleaching from LRR. Among the conditions tested, the A. thiooxidans system achieved a Li leaching efficiency of 26.7
Low solids loading is commonly applied in various pretreatment operations of lignocellulose biomass, especially for acid-catalyzed pretreatment. However, low solids loading condition inevitably leads to the generation of liquid streams containing considerable sugars and inhibitors. This study calculated the mass and energy balances for sulfuric acid-catalyzed pretreatment of sugarcane bagasse at a typical solids loading corresponding to a solid-to-liquid ratio of 1:20. A large volume of pretreatment liquor (18.5 g/g dry matter), which contained 27.4
