Bioprocess and Biosystems Engineering最新文献

Maintaining high protein purity is crucial for ensuring the efficacy, safety, and productivity of therapeutic glycoproteins. Given that proteins produced within transient gene expression (TGE) systems are ultimately intended for incorporation into production cell lines developed using stable gene expression (SGE) systems, it is crucial to evaluate protein purity across both systems and explore strategies for improvement. In this study, elevated levels of both high- and low-molecular-weight impurities were observed in etanercept (ETN) produced under the evaluated TGE conditions compared with the SGE system. To address these purity concerns, we investigated the effects of various process modifications, including chemical treatments, temperature downshifts, and adjustments to kit components within the TGE system. Results indicated that rapamycin treatment, a temperature downshift to 30 °C, and the omission of Enhancer material increased the monomer proportion of ETN. Combining a temperature downshift to 30 °C with omission of the Enhancer material reduced overall ETN production but increased the monomer ratio to levels comparable to those in the SGE system. Moreover, the combination of rapamycin treatment, a temperature downshift to 30 °C, and an extended culture duration significantly enhanced both total and monomer ETN production while maintaining higher purity. These improvements were similarly observed in the HEK293 cell-based TGE system, demonstrating that the optimized culture conditions possess broad applicability across mammalian TGE systems. These findings demonstrate that comprehensive optimization of culture parameters can significantly enhance protein purity in TGE-based protein production, enabling purity levels comparable to those obtained from SGE systems under the conditions evaluated in this study.

The challenge associated with agricultural straw pretreatment before anaerobic digestion (AD) lies in overcoming biomass recalcitrance at a low cost while minimizing the wastewater that requires additional purification. Biogas slurry from AD itself, rich in ammonia nitrogen and microorganisms, can pretreat straw instead of ammonia reagents or microbial agents. This study explored a synergistic pretreatment approach, particularly relevant in cold regions that offer natural cold resources, involving the immersion of straw in biogas slurry, followed by freeze-thaw cycles. Research findings indicated that freeze-thaw treatment significantly enhanced the lignin removal of biogas slurry immersion. Although sealing offered advantages for biogas slurry pretreatment, open was also feasible in terms of lignin removal and volatile fatty acids production, which helps further reduce operating costs. The hydrolytic acidification mediated by microorganisms, such as Clostridium sensu stricto 1 and Comamonas, dominated the biogas slurry immersion process, rather than the ammonolysis driven by free ammonia. The delignification process of rice straw underwent significantly interactive effects by several factors, reaching maximal lignin removal rates of 63.27% and 39.16% under sealed and open immersions, which corresponded to the optimal pretreatment conditions: immersion temperature of 30.70 and 43.20 °C, immersion durations of 4 days and 20 h, biogas slurry-to-straw ratios of 16.33:1 and 14.62:1, both followed by four freeze-thaw cycles. The specific methane yields under the two optimal conditions reached 281.37 and 262.18 L/kg VS. The combined pretreatment presents a promising low-cost operational strategy, especially in cold regions, while also facilitating on-site utilization of biogas slurry.

Although macroalgae are promising biosorbents for the removal of various contaminants, their effectiveness in complex mixtures requires comprehensive comparative evaluation under multi-contaminant conditions. The ability of living and non-living Ulva lactuca and Gracilaria gracilis to simultaneously uptake Rare Earth Elements (REEs) (Y, La, Nd, Eu, Gd, Dy) and classical contaminants (Hg, Cd, Pb, As) from equimolar mixtures was compared. Batch sorption experiments were conducted for 72 h under optimised conditions of salinity (10) and pH (7.8), in which 5 g of living biomass and an equivalent non-living biomass (0.60-0.85 g) were exposed to contaminated seawater (1 L) under constant stirring (800 rpm). The living biomass exhibited high removal rates (> 80%) for REEs, Hg, and Pb, while for As and Cd, lower removals were achieved. Non-living biomass showed significantly lower removal ability for REE (generally < 40%). These findings suggest a two-step approach, exploiting, first, non-living biomass to remove common contaminants and, after, living biomass for bioaccumulating REEs, which could later be recovered for reuse.

While bran-free fermentation contributes to enhancing the sensory quality of Sichuan Qingxiangxing Baijiu, its process efficiency often falls short of the optimum level, particularly manifested as a low liquor yield. To address this bioprocess limitation, this study implemented a targeted microbial biofortification strategy by introducing specific exogenous strains. This approach significantly improved starch utilization efficiency, increasing the liquor yield from 42 to 55%. Simultaneously, the concentrations of key flavor esters (such as ethyl acetate and ethyl lactate) were markedly elevated, achieving a synergistic optimization of production efficiency and product flavor. System-level analysis revealed that the introduction of exogenous strains served as a key driver in reshaping the succession dynamics of the microbial community. By modulating intraspecific competition and interspecific cooperation, they reconstructed the metabolic network, which was closely associated with the earlier and higher-level formation and accumulation of volatile flavor compounds. This study applies biofortification technology to bran-free Qingxiangxing Baijiu production, offering a novel bioprocess control strategy for the simultaneous enhancement of yield and flavor in traditional solid-state fermentation systems.

Lactate-, ethanol- and citrate-rich side streams are increasingly available from waste fermentation and organic-acid industries, yet their effects on carbon allocation in mixed-culture activated sludge remain insufficiently compared under identical conditions. Here, we operated three parallel sequencing batch reactors fed with lactate, ethanol, or citrate and quantified treatment performance together with chemical oxygen demand (COD) partitioning to intracellular polyhydroxyalkanoates (PHA) and extracellular polymeric substances (EPS). All reactors maintained stable removals of COD, total nitrogen, and total phosphorus above 80%. However, carbon allocation differed strongly. Biomass accumulated about 20 to 30 mg/g volatile suspended solids, corresponding to COD to PHA recoveries of 60.7% for lactate, 37.9% for ethanol, and 39.6% for citrate. Lactate minimized the non-PHA COD fraction and produced polyhydroxybutyrate-valerate with the highest hydroxyvalerate share, whereas ethanol favored polyhydroxybutyrate rich PHA and diverted more carbon to EPS and respiration. The EPS matrix was protein-dominated and more humified under ethanol, moderately protein-rich under lactate, and more polysaccharide-biased with weaker humic-like signals under citrate. Community profiling supported these shifts, with lactate enriching storage-oriented guilds, ethanol enriching denitrifying and EPS-producing guilds, and citrate supporting an enhanced biological phosphorus removal like community. Together, these results show that substrate chemistry beyond conventional volatile fatty acids can be used to steer the balance between PHA storage and EPS formation while maintaining nutrient removal.

The utilization of Baijiu distiller's grains (BDGs), commonly used as a feed ingredient, remains limited due to challenges such as elevated levels of anti-nutritional factors (ANFs), high fiber content, and low protein concentration. Microbial fermentation has been recognized as an effective strategy to improve the nutritional quality of feed substrates. However, its efficacy is highly dependent on process parameters such as temperature. Despite its significance, the effect of temperature on the interaction between microbial communities and the physicochemical properties of BDGs during fermentation remains poorly understood. To address this gap, BDGs were fermented using Bacillus subtilis, Candida utilis, and Geotrichum candidum under varying temperatures. Comprehensive physicochemical analyses combined with high-throughput sequencing of microorganisms were performed to investigate the dynamic changes in both fermentation products and microbial kinetics. The results revealed that the optimal fermentation performance was achieved at 34 °C. At this temperature, compared to untreated BDGs, phytic acid, tannin, and crude fiber levels were significantly reduced by 65.18%, 30.69%, and 15.34% respectively, whereas crude protein and amino acid contents increased by 15.5% and 7.13%. Furthermore, temperature was found to play a crucial role in shaping the dynamics of microbial community succession, with Stenotrophomonas, Bacillus, Pseudomonas, Paenibacillus, and Pediococcus identified as key bacterial genera influencing the nutritional composition of BDGs. Temperature variations drive shifts in microbial communities and consequently affect the nutritional quality during fermentation. These findings provide valuable experimental evidence and support the potential of fermented BDGs as a viable protein ingredient substitute in animal feed.