Bioprocess and Biosystems Engineering最新文献

In large-scale bioprocesses, gradients in pH, dissolved oxygen level (DO), and substrate concentrations can decrease bioprocess efficiency. Scale-down bioreactors, be it single stirred-tank bioreactors with a special feeding regime, multi-compartment bioreactors, or combinations of bioreactors, offer a promising lab-scale solution for comprehending these gradients, as they allow adjustment of gradients without incurring high costs. However, critical challenges arise when transitioning from large-scale to scale-down bioreactors. Chief among these is realistically approaching the gradient conditions of large-scale bioreactors and choosing appropriate scale-down bioreactor configurations. This review paper begins by addressing the gradients encountered in large-scale bioreactors. Afterward, various types of scale-down bioreactors are characterized and compared, highlighting their advantages and disadvantages. The suitability of scale-down bioreactors is analyzed by examples of bioprocesses with different microorganisms and mammalian cells to underscore the complexities inherent in scale-down bioprocesses and emphasize the influence of cellular responses to these conditions. Finally, the potential of miniaturized and microfluidic bioreactors is briefly discussed for future application in scale-down studies.

Microbial fuel cells (MFCs) have been proven to be a green technology for solving energy crises, but their low power density limits their large-scale practical applications. In this paper, a three-dimensional porous composite hydrogel polyvinyl alcohol/polypyrrole (PVA/PPy) with good biocompatibility was prepared by temperature-field regulation via alternating cycles between low temperature (- 20 °C) and room temperature (25 °C) and used as the anode in MFC. The three-dimensional network structure of PPy nanospheres compressed by ice crystal stress exhibited excellent charge conduction capability and ion transport performance, which significantly improved the interfacial charge transfer efficiency of PVA/PPy-5 bioanode. Besides, the addition of PVA endowed the hydrogel with mechanical properties to resist the external forces. As the results, the maximum power density of PVA/PPy-5 MFC was 1521.04 mW/m², which was 1.76, 2.16 and 8.32 times higher than that of PVA/PPy-0, PPy-5 and carbon felt MFCs, respectively. Such enhancement could be attributed to the combined effects of three factors, including the FT process, biocompatibility of PVA, and bioelectrocatalytic activity of polypyrrole. The high-throughput sequencing technology revealed that the PVA/PPy-5 hydrogel anode, which facilitated the selective enrichment of electrogenic microbes, played a crucial role on the regulation of functional biofilm. This work provides a new approach for developing high-performance electrodes for MFC.

The utilization of semi-simultaneous saccharification and fermentation (SSSF) as the novel configuration has resulted in enhanced succinic acid (SA) production from lignocellulose biomass by Actinobacillus succinogenes. The effect of inoculum concentration, biomass type, substrate concentration, and fermentation configuration on SA production was examined in this study. The pre-hydrolysis process was applied to the pre-treated biomass for 6 h to facilitate the simultaneous saccharification and fermentation (SSF) process, which was then carried out for 48 h to achieve the SSSF configuration. According to the results, the production of SA from oil palm empty fruit bunch (OPEFB) through SSF and SSSF was 0.93 and 1.18 g/L and from sugarcane bagasse (SB) was 0.98 and 1.19 g/L, respectively. Results revealed, SSSF resulted in a 21-26% higher SA concentration compared to SSF. Furthermore, the concentration of the inoculum and substrate significantly affected the generation of SA from OPEFB but not for SB. According to this study, SSSF significantly enhanced SA production from lignocellulose biomass compared to SSF.

The intensive agricultural practices used to meet global crop production demands have resulted in rigorous use of chemical pesticides. These ultimately compromise crop production as well as the environment. To alleviate these challenges, cheaper and environmentally friendly biocontrol agents have been considered as an alternative to chemical pesticides. Hence, this study was undertaken with the aim of enhancing antifungal production by Bacillus subtilis BS20 through process modeling, optimization, nanocatalysis and subsequent assessment of the scale up potential of the optimized process. The investigated process parameters included glucose concentration (10-30 g/L), incubation temperature (25-45 ℃) and incubation time (24-96 h). Optimized process conditions of 11.5 g/L glucose concentration, 24 h incubation time and 41 °C incubation temperature produced maximal antifungal activity of 68 mm zone of inhibition. Moreover, the inclusion of nanoparticles favored increased biomass yield but low antifungal activity. Additionally, constant power consumption, Reynolds number (Re) and impeller tip (V_tip) speed were implemented to scale up the antifungal production by B. subtilis BS20. Implementing constant V_tip value from the 1 L scale: 93 rpm, Re = 5.9E-04, Power (P) = 0.32 W, Power to Volume ratio (P/V_L) = 160 W/m³, circulation time (t_c) = 5.2 s and shear stress (γ) = 15.5 S^-1, at 41 °C, gave the highest antifungal activity of 65 mm zone of inhibition in the 10 L scale bioreactor compared to the 1L bioreactors (57 mm). These findings have elucidated improved antifungal production by B. subtilis BS20 as well as provided a preliminary data for large scale production.

Dairy industry generates wastewater characterized by organic components, predominantly composed of proteins and fats, which can be effectively treated through biological processes. The present study aims to develop a bacterial consortium for bio-augmentation to enhance the treatment of simulated dairy wastewater. A total of 75 bacterial isolates were obtained using direct (DI) and enrichment-isolation (EI) methods. Among these, four strains exhibiting the highest proteolytic and lipolytic activities within 24 h were selected for further investigations. The isolates were screened based on their extracellular enzyme activities (proteinase and lipase), as well as their maximum lipolytic (0.3-0.7 mm/h) and proteolytic activity (0.67-0.83 mm/h) by a novel approach of rate of diffusion on TA and MSMA, respectively. The selected strains were identified by 16S rRNA gene sequencing as Massilia (DSSC1), Brevibacillus (ENAT1), Pseudomonas (ENOG5), and Lysinibacillus (ETOG2). The biodegradation potential of individual strains and their consortium was assessed through COD reduction in simulated dairy wastewater. The individual bacterial strains achieved COD reductions from an initial concentration of 3.82 g/L to 2.95, 2.81, 2.48, and 2.89 g/L. In contrast, bio-augmentation with the bacterial consortia reduced COD to 2.19 g/L, resulting in a 26-86% higher reduction compared to the individual strains. This study presents the first report on the use of a novel approach of diffusion-based assay to develop an effective and innovative bacterial consortium for efficient dairy wastewater treatment. These findings highlight the potential of this approach toward enhancing biodegradation efficiency and advancing sustainable wastewater management practice.

Economically viable production of poly(3-hydoxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymers remains a challenge. The objective of this work was to produce low-cost PHBV copolymers from lignocellulose-derived mixed sugars without genetic engineering or addition of chemical precursors. A hardwood hydrolysate was first pre-fermented using the facultative anaerobe Propionibacterium acidipropionici, and the resulting propionate-rich effluent was used for subsequent PHBV biosynthesis in Paraburkholderia sacchari or Hydrogenophaga pseudoflava. P. acidipropionici displayed a high tolerance to the hardwood hydrolysate and produced up to 11 g L^-1 propionate (with varying amounts of lactate and acetate) under batch conditions. Propionic acid exerted significant toxicity toward P. sacchari and H. pseudoflava, so dilution of the pre-fermentation effluent was required prior to the PHBV production step. When P. sacchari and H. pseudoflava were grown on the pre-fermented mixture of glucose, xylose, lactate, acetate, and propionate (diluted to 15 mM propionate), the organic acids were consumed preferentially. H. pseudoflava accumulated up to 41.7 ± 7.0% cell dry mass (CDM) as PHBV that contained 13.7 ± 2.4 mol % 3-HV subunits. Meanwhile, P. sacchari accumulated up to 56.0 ± 5.8% CDM as PHA, but with lower 3-HV contents (1.2-5.1%). The PHBV copolymers resulting from this integrated process showed a desirable crystallinity, but the molecular weights were lower and the melt temperatures were higher than expected in all cases. Future work should focus on tuning the cultivation parameters to target higher molecular weight polymers while designing a feeding strategy of the pre-fermented stream that circumvents toxicity issues and allows a better control of the formation of random vs. block copolymers.

Co₃O₄/rGO nanoparticles were used to modify a glassy carbon electrode (GCE), where reduced graphene oxide (rGO) serves as an intermediate between graphene and graphene oxide, featuring a carbon framework enriched with oxygen-containing hydrophilic functional groups. The structural and morphological characterization of the modified electrode was carried out using Raman spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS). Electrochemical performance was evaluated through cyclic voltammetry (CV) and chronoamperometry, revealing effective electron transfer between the nanoparticles and immobilized choline oxidase (ChOx). The apparent heterogeneous electron transfer rate constants (K_s) were calculated as 0.99 s^-1 for Co₃O₄/rGO and 5.89 s^-1 for ChOx/Co₃O₄/rGO. The biosensor demonstrated excellent analytical performance for choline detection, with a linear response range of 5-60 µM, a sensitivity of 0.0216 µA µM^-1, and a detection limit of 0.811 µM. Notably, the developed biosensor also exhibited a strong electrochemical response to the organophosphorus pesticide diazinon, indicating its potential for environmental monitoring. Given that diazinon is a widely used organophosphorus pesticide with high toxicity to humans and the environment, its sensitive detection is critical for monitoring and controlling pesticide contamination.

Combining partial nitrification and anammox with denitrifying phosphorus removal (DPR) is considered a promising strategy for nitrogen and phosphorus removal. However, the low nitrate nitrogen availability (produced from anammox) in the side-stream DPR system could affect nutrient removal and the competition between denitrifying phosphate-accumulating organisms (DPAOs) and denitrifying glycogen-accumulating organisms (DGAOs). In this study, the nitrogen and phosphorus removal performance, microbial structure shifts, and key functional groups in a DPR reactor were investigated under long-term nitrate-limited conditions. Over 205 days of DPR operation, with the nitrate concentration at the beginning of the anoxic stage gradually decreasing from 15 to 7.5 mg/L, stable and efficient nitrogen removal was maintained, while phosphorus removal efficiency reached 96.7 ± 1.6%, despite a reduction in phosphorus release amount. Microbial community analysis revealed that Candidatus_Competibacter became dominated, increasing from 2.3% to 42.2%, which contributed to efficient nitrogen removal. Meanwhile, DPAOs declined to a certain abundance but still maintained phosphorus removal performance. The result indicated that carbon and nitrate availability are the key factors driving microbial succession in the DPR system. Additionally, short-term batch tests demonstrated that the DPR system remained its capability to handle higher nitrate concentrations after long-term nitrate-limited conditions.

Plasma is the primary microenvironment, where red blood cells (RBCs) survive and function, with its components playing crucial roles in erythroid expansion and RBC functionality. This study aims to elucidate the relationship between the combination of critical components in plasma and the expansion and cell state of erythroid cells. Using Design of Experiment (DOE) methods, we screened and optimized the concentrations of plasma components that significantly impact the in vitro expansion of TF-1 cells. We identified a plasma substitute combination composed of hypoxanthine, dexamethasone, and vitamin B complex and, significantly enhancing TF-1 cell expansion in the serum-free medium supplemented with bovine serum albumin by 1012.41 folds, compared to 327.50 folds in the negative control. In addition, the proportion of CD34⁺ cells in the medium supplemented with this combination was 54.77%, comparable to the negative control, while hemoglobin expression was 0.64 pg/cell, significantly higher than that of the negative control. Given that various components of this formulation affect intracellular redox status and signaling pathway activation, we further investigated these aspects. Cells cultured with this combination showed improved mitochondrial membrane potential, lower intracellular reactive oxygen species (ROS) levels, reduced apoptosis rates, and enhanced STAT5 phosphorylation. These results indicated that the plasma substitute combination improves intracellular redox status and activates the JAK/STAT signaling pathway in TF-1 cells. This study provides valuable insights for developing serum-free media for the in vitro expansion of erythroid cells.

The shift toward sustainable biofuels and bioproducts has increased interest in microbial production systems using renewable substrates. This study explores the use of wood hydrolysate, an abundant, cost-effective lignocellulosic substrate, as the primary carbon source for lipid and carotenoid production by Rhodosporidium toruloides-7191 under fed-batch cultivation in a 3-L bioreactor. The fed-batch strategy, chosen over batch and continuous modes, enables controlled nutrient supply, minimizes substrate inhibition, and maintains a favorable carbon-to-nitrogen ratio, thereby supporting prolonged biosynthesis and higher product yields. The process achieved a maximum lipid production of 22.33 g/L, a total lipid accumulation of 57.9% and a total carotenoid production of 4.23 mg/L. Fatty acid analysis shows a composition rich in linoleic acid (C18:2), oleic acid (C18:1), and palmitic acid (C16:0), indicating its suitability for biodiesel applications. The results emphasize R. toruloides-7191 as a promising candidate for industrial-scale applications, advancing sustainable production of biofuels and high-value bioproducts. The effectiveness of wood hydrolysate as a substrate further supports the feasibility of this approach, highlighting its potential in advancing industrial-scale processes for the production of biofuels and value-added compounds.