Bioprocess and Biosystems Engineering最新文献

Upstream bioprocessing is a very complex system and requires rapid responses to process deviations. Mammalian cell culture processes are conventionally monitored for process-related and cell growth-related parameters, including pH, dissolved oxygen, viable cell density, cell viability, and key analyte concentrations that serve as primary indicators of the metabolic state of the cell culture. Raman spectroscopy (RS) has been increasingly applied as a viable inline process analytical technology (PAT) tool for cell culture monitoring and prediction of key analytes and attributes. The primary limitation to RS in these measurements is fluorescence (also referred to as sample-induced fluorescence), which interferes with the Raman signal and creates noise that makes detection of the signal from the analytes difficult. As a result, fluorescence interference decreases the signal to noise ratio (SNR) of the acquired spectra and increases the limit of detection (LOD) of analytical methods. Time-gated Raman spectroscopy (TGRS) takes advantage of the temporal delay between inelastic light scatter (Raman signal) and fluorescence emission to reduce interference from fluorescence. In this study, a pure component modeling approach and Net Analyte Signal (NAS) were applied to calculate the SNR and LOD of independent CHO cell culture samples. By reducing fluorescence interference, improving the SNR and LOD, TGRS enhanced the detectability of five key analytes in the cell culture samples, facilitating accurate monitoring and detection of analytes in a complex bioprocess system, thereby demonstrating its viability as a PAT tool for upstream bioprocess environment.

Volatile fatty acids (VFAs) derived from organic waste offer promising and cost-effective carbon sources for the production of microbial lipids. This study demonstrates the significant influence of nitrogen nutrition on cell proliferation and microbial lipid synthesis in Yarrowia lipolytica during high-concentration acid cultivation. Further investigations into nitrogen sources revealed that NH₄Cl and urea are suitable options for cultivating Y. lipolytica to produce microbial lipids, resulting in lipid yields ranging from 2.00 to 2.50 g/L. Moreover, pH fluctuations were found to be influenced by both the nitrogen source and acid utilisation, with pH adaptation helping alleviate acid inhibition caused by high-concentration VFAs. Under optimised cultivation conditions, the highest yield of microbial lipids reached 4.00 g/L, accompanied by a dry cell weight of 9.91 g/L and a microbial lipid content of 40.37%, consisting predominantly of C16 ~ 18 fatty acids. These findings highlight the central role of nitrogen metabolism and pH adaptation in enhancing VFA assimilation, offering guidance for cost-effective microbial lipid production from organic waste streams.

The production of a functional ingredient (FI) containing Lactobacillus acidophilus (ATCC 4356) immobilised in oat bran was designed and optimised. The effects of the independent variables, incubation time and hydration level, were analysed and optimised to simultaneously maximise the cell count and growth, as well as the yield of the obtained FI and the resistance of the probiotic to simulated gastric conditions after 7 days of storage at 25 °C, minimising pH and nutrient loss (proteins and carbohydrates) in the washing water. The optimal design conditions found were 60 h of incubation and 13 mL of water/g oat bran. The growth kinetics of L. acidophilus was determined for the optimal system, showing no lag phase and the maximum specific growth rate (µ_max) of 1.1 ± 0.1 h^- 1. The system with an optimal hydration level (13 mL/g oat bran) and 36 h of fermentation was selected for being scaled-up in one order of magnitude. A reduction in cell growth, in the FI yield, and an increase in the value of the titratable acidity of the recovered supernatants were observed. During the fermentation, the acids produced were mainly lactic acid followed by acetic acid. It must be highlighted that the fermentation process proposed, reduced the initial oxalic acid content in oat bran. The production of FI based on oat bran containing L. acidophilus represented a sustainable process that also improved the nutritional aspects of the raw material. Oat bran could be by itself an adequate support for L. acidophilus storage stabilisation.

Accurate real-time estimation of system states and metabolic parameters is essential for effective bioprocess control. However, the dynamics of microbial adaptation-the rate at which a microorganism adapts to changes in the substrate concentration-is often overlooked, leading to early-stage plant-model mismatches and inaccurate estimation of relevant parameters, such as the biomass yield on carbon source ([Formula: see text]) or the maximum substrate uptake rate ([Formula: see text]). This work introduces a novel model-based observer for simultaneous state and parameter estimation that explicitly accounts for substrate uptake dynamics. By defining the substrate uptake rate ([Formula: see text]) as a state variable and introducing a random variable (λ) to represent the biomass-specific substrate uptake adaptability rate, we construct a Bayesian estimator that allows proper determination of the states and parameters in fed-batch fermentations of E. coli while maintaining near-zero centered residuals between the plant output and the proposed model stoichiometry. This work advances methods for robust state and adaptive parameter estimation in dynamic bioprocess environments under uncertainty.

Biohydrogen (BioH₂) production from waste resources, such as food waste, is a potential source of sustainable and clean energy. Previous literature has reported enhancement in the kinetics and yield of dark fermentation for bioH₂ production using sonication. However, the mechanism by which sonication affects the cellular metabolism has remained largely unexplored. The present study aims to investigate the effect of ultrasound on the metabolic network of Clostridium pasteurianum during the dark fermentation of food waste hydrolysate and to elucidate the underlying mechanism using metabolic flux analysis (MFA). A metabolic flux model was developed to determine the impact of sonication on intracellular metabolite fluxes. Hexose sugar uptake increased by ~ 47% with sonication, while butyrate and acetate fluxes at the acetyl-CoA node increased by ∼9% and ∼94%, respectively. Sonication improved bioH₂ yield by ∼22%, and the acetate-to-butyrate (A/B) ratio by ∼37%. These results pointed out that bioH₂ production is linked to carbon flux at the acetyl-CoA node. A higher flux towards the acetate route (compared to the butyrate route) enhances hydrogen yield. Based on these results, a hypothetical MFA analysis (with sonication) was conducted for two cases: (1) complete redirection of carbon flux at the acetyl-CoA node to the acetate route, and (2) doubling the uptake flux of hexose sugars. For the first case, bioH₂ enhanced from 4.13 to 6.47 mmol/L⋅h, while in second case, bioH₂ flux of 14.53 mmol/L⋅h was predicted by MFA model. These results could be useful for the genetic engineering of microbial strains for enhanced bioH₂ production.

This study aimed to improve methyl tertiary butyl ether (MTBE) degradation and power production in microbial fuel cells (MFCs) by employing an iron nanoparticle-coated graphite carbon electrode (Fe-GCE), co-metabolites (sodium acetate (SAC) and glucose (GLS)), and surfactants (sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB)). Fe-GCE enhanced the roughness and hydrophilicity of the electrodes, thereby promoting their electrochemical activity. This study compared the use of polyvinyl alcohol/glutaraldehyde (PVA/GA) and Nafion 117 membranes and the impact of carbon sources and surfactants on the performance of MFCs. The optimal conditions achieved 97.9% MTBE removal (10 mg/L) within 96 h by employing SAC and SDS in Nafion 117-MFC with a voltage of 335 mV in synthetic wastewater. Fe-GCE exhibited minimal antibacterial action and iron leaching (< 0.3 mg/L in 30 days), suggesting its stability during wastewater treatment. Bacterial community profiling revealed that Bacillus, Alcaligenes, Trichococcus, and Magnetospirillum were the main MTBE degraders. Statistical analysis validated substantial improvement in MTBE removal and voltage yield with the use of additives, and that PVA/GA-MFC had performance similar to Nafion 117-MFC, providing a cost-effective alternative with potential commercial success. This study provides insights into the potential use of MFCs for treating recalcitrant pollutants while producing green energy, paving the way for eco-friendly waste management strategies.

Microbial fermentation for succinic acid production has the advantages of a short production cycle, renewable raw materials, and mild reaction conditions, and is recognized as a promising green approach. However, the succinic acid fermentation process is often accompanied by by-products such as formic acid and acetic acid, which increase the cost of subsequent separation and waste resources. This study proposed a green integrated process in which Rhodotorula glutinis As2.703 was used to selectively metabolize formic acid and acetic acid in succinic acid fermentation broth to produce high-value-added single-cell protein (SCP), while succinic acid was retained. The results showed that R. glutinis As2.703 achieved a utilization rate of 100% for formic acid and acetic acid in succinic acid fermentation broth, with a biomass of 7.05 g/L and a biomass yield of 0.46 g/g. The protein, lipid, and carotenoid contents in SCP were 53.11%, 16.65%, and 194.15 µg/g, respectively. SuperPro Designer^® was used to simulate the process of producing 54,331 tons of succinic acid annually. After integrating the SCP production module, the process achieved an annual output of 11,935 tons of SCP, with an annual revenue of 19.81 million USD. The operating cost for the SCP module was only 8.27 million USD/year, resulting in a net annual profit of 11.54 million USD. This technology not only reduced the separation cost of succinic acid but also provided a high-quality protein source for the feed industry, significantly improving the economic viability and sustainability of succinic acid production.

The development of innovative bioprocessing technologies has resulted from the growing global need for sustainable forms of energy and environmentally friendly waste treatment. In this review, we focus on the combined electro-fermentation and microbial fuel cells, as they form a hybrid system that simultaneously addresses wastewater treatment, bioenergy production, and bioplastics. Even though microbial fuel cells produce electricity out of the organic waste by the use of electroactive microorganisms, electro-fermentation improves the microbial pathways through the external electrochemical management. The novelty of the review is that it compares the two technologies in detail and identifies the synergistic potential of the technologies as well as assesses the efficiencies of their operations, scalability, and impact on the environment. The research utilizing Scopus and PubMed directories was done by means of a systematic literature review that included 147 peer-reviewed experimentation and technology-oriented studies published during the period of 2012-2024. The main results lead to the conclusion that integrated systems imply significant increase in power densities (up to 2000 mW/m²), the enhancement of electron transfer efficiency (increased by 30-40%), large-scale production of useful products such as methane, hydrogen and organic acids. In spite of this promise, there are still difficulties regarding microbial stability, material costs, and energy balance. The review identifies the existing gaps and future opportunities, which include the development of novel electrode materials, the employment of better reactor designs and designer microbial consortia. The combination of such systems may become an interesting strategy of the next generation of biorefineries and have a good prospect to become a part of the circular economy and climate as a whole.

Phenolic compounds in oats contribute to their health benefits but predominantly exist in insoluble bound forms with low bioaccessibility. To address this issue, this study developed a phased processing strategy combining enzymatic hydrolysis and Monascus fermentation to enhance the release of bioactive phenolic in oats. Results showed that adding cellulase in the mid-fermentation stage effectively increased the phenolic content by 21.23 times (23.34 mg GAE/g DW), compared with unfermented oats. HPLC analysis revealed substantial increases in free phenolic acids, with vanillic acid and chlorogenic acid contents rising to 215.22 mg/kg (35.92-fold) and 150.90 mg/kg (16.00-fold), respectively. Structural analysis via scanning electron microscopy confirmed the degradation of oat cell walls, supporting microbial growth and facilitating phenolic compound release. The free phenolic fractions exhibited potent antioxidant activities, which were strongly correlated (r > 0.91, p ≤ 0.001) with chlorogenic acid, quercetin, and vanillic acid content. These results demonstrated that the combined microbial-enzymatic approach was a highly effective bioprocessing strategy for producing value-added oat products with enhanced phenolic bioaccessibility and antioxidant capacity.

The goal of the present study was to define better conditions for the invertase production from the yeast Rhodotorula toruloides in the surface adhesion fermentation (SAF) in the presence of magnetic chitosan-coated (MnFe₂O₄-Ch) manganese ferrite nanoparticles and to evaluate their reuse in different fermentation cycles. The synthesis of MnFe₂O₄-Ch was performed using the one-step chemical coprecipitation method, which was assisted with hydrothermal treatment. Box-Behnken design was applied to establish the relationship between the selected parameters. The reuse of the immobilized biomass was evaluated with and without the MnFe₂O₄-Ch addition in several fermentation cycles. According to X-ray diffraction results, the MnFe₂O₄-Ch exhibited a spinel structure with a crystallite size of 20.73 nm. The mean particle hydrodynamic size was 181.7 nm, the magnetic saturation was measured to be 39.6 emu/g at 20 kOe and 300 K. The growth of R. toruloides microorganism was stimulated with MnFe₂O₄-Ch, and a more significant effect was observed at the concentration of 2 mg/mL. The microorganism produced an invertase enzyme, and higher enzyme activity (1.88 IU/mL) was detected with the MnFe₂O₄-Ch at 1 mg/mL. The enzymatic activity increased by 69% in surface adhesion fermentation compared to submerged fermentation. In the third cycle of SAF with reused immobilized yeast and MnFe₂O₄-Ch addition, the enzymatic activity increased compared to the first two cycles of reuse, reaching values without significant difference compared to the enzymatic activity in the initial SAF. Surface adhesion fermentation may be an appropriate method to improve invertase production from R. toruloides.