Bioprocess and Biosystems Engineering最新文献

The rising demand for spirulina (Limnospira spp.) highlights the need for affordable cultivation methods and practical biomass monitoring solutions. This study introduces a novel, low-cost, Raspberry Pi-based system for real-time monitoring and automated biomass recovery in microalgal cultivation. The system integrates turbidity, light, pH, and temperature sensors with an automated module for harvesting and medium replenishment. Cultures of the filamentous, spiral-shaped microalga Limnospira fusiformis were used to evaluate system performance. The turbidity sensor showed strong correlation with optical density (R² = 0.943-0.986, p < 0.05) and dry weight (R² = 0.954-0.975, p < 0.05). Light, pH, and temperature sensors demonstrated average percentage errors of 0.50%, 0.58%, and 2.52%, respectively (p < 0.05). The auto-recovery system successfully maintained biomass concentration within a narrow range (OD₇₅₀ = 0.67-0.74) using adjustable set points tailored to cultivation needs. Real-time data were auto-logged to Google spreadsheets for remote access. With an estimated cost of $340, the system offers a practical, time-saving, and cost-effective solution for real-time biomass monitoring and control in microalgae cultivation.

Despite many reports focusing on the engineering aspects of biodesulfurization, there is a lack of comprehensive analysis on metabolic pathways and integration of engineering and metabolism. In this study, a genome-scale metabolic model was reconstructed for Thioalkalivibrio versutus D301, a potent strain in biodesulfurization. The model, named TVD301, was refined using extracted RNA sequencing data, and flux balance analysis demonstrated its accuracy in predicting growth and sulfur species rates. Importantly, experimental validation in a regulated medium confirmed a 60% decrease in sulfate production compared to control cultures, showing the strong practical relevance of the model. The TVD301 model also revealed that T. versutus lacks the enzymes needed to convert sulfide to sulfate, making it a strong strain in biodesulfurization. To optimize sulfur recovery and reduce sulfate production in industrial processes using microbial consortia, the TVD301 model was adapted to a consortium model. Sensitivity analysis highlighted the importance of DsrAB and Cys enzymes in preventing undesired sulfate production. By inhibiting these enzymes via inhibitors extracted from Brenda database, elemental sulfur production increased significantly. These findings suggest promising strategies for enhancing biodesulfurization processes in industrial settings.

Production of Fab (fragment antigen-binding) molecules using Escherichia coli as a host presents a significant challenge due to low protein expression and the resulting poor yields. In this study, recombinant Ranibizumab was expressed in E. coli as inclusion bodies (IB) and optimization of lysis parameters, IB recovery, and IB washing conditions was performed to achieve optimal product yield and purity. Design of experiments (DOE) was employed to explore the interaction between variables and to facilitate optimization of buffer composition. Optimization of lysis buffer resulted in a yield of 0.069 g protein/g IB, 61% IB purity, and 87% lysis efficiency. Optimization of homogenization conditions, using two passes at 1000 bar, resulted in a 93.5% lysis efficiency with 60% IB purity. Additionally, optimizing the IB washing steps with 1% Triton X-100 and 2 M urea for 30 min at room temperature offered 84.53% IB recovery and 75% IB purity. Further, the impact of IB quality on refolding yield has been examined. Overall, the process optimization translated into a significant improvement in refolding yield, which increased from 18% under unoptimized conditions to 29% post-optimization and it has been demonstrated that optimization of lysis and washing steps can significantly enhance refolding yield, a key hurdle when expressing Fabs in E. coli.

The generation of food waste poses an escalating societal challenge. Anaerobic digestion emerges as a sustainable and eco-friendly method for valorization and disposal. A small-scale floating-drum-type digester was developed, operating in batch mode to harness biogas from three distinct food waste categories. Potato waste, leftover cooked food, and fish waste were utilized as feedstock, maintained at an average temperature of 21 °C for a retention time of 10 days, with cow manure serving as the inoculum source. The advances of the current work are built upon comparing biogas production volume and methane content from mono-anaerobic digestion of these various wastes. Examining cow manure and different substrate samples offers insights into their composition, encompassing total solids, C/N ratio, and pH. Shredded raw wastes were wet fed into the digester at a 1:1 waste/water ratio. Cumulative production of biogas and the methane fraction from two experiments were monitored. The maximum average cumulative biogas production per kg of total solid was observed for leftover cooked food (up to 261.4 L/kgTS), followed by fish waste (up to 248.5 L/kgTS) and potato waste (up to 137.15 L/kgTS). The maximum methane percentage occurred in fish waste displaying the highest methane percentage (74%), trailed by leftover cooked food (59%) and potato waste (55.8%) from both experiments.

Polyhydroxyalkanoate (PHA) is a bioplastic attracting interest as an alternative to petroleum-based plastics. Particularly, poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)), which shows notable polymeric properties, is usually produced using the engineered Cupriavidus necator. Currently, production of P(3HB-co-3HHx) is primarily possible by engineering phaC, however, relatively rare study of controlling the expression of enoyl-CoA hydratase (phaJ_Pa), which is directly involved in 3-hydroxyhexanoate (3HHx) monomers synthesis, was shown to control 3HHx mole fraction. As a result, we aimed to verify this by constructing vectors housing phaC_BP-M-CPF4 and phaJ_Pa with different ribosome-binding site (RBS) to control PhaJ translation. When different constructions were applied, the fluctuation in the 3HHx molar fraction was directly related to the phaJ_Pa RBS sequence and it was shown that varying the RBS sequence to AAAGGAGATATAG produces increased 3HHx mole fraction (3.6-6.2%). When fermentation was performed for 168 h to verify the capacity of the engineered strain (H16/pSJ-3) for mass production, it produced 194.9 g/L dry cell weight and 155.4 g/L of P(3HB-co-9.5 mol% 3HHx). Overall, this study presents a different approach of altering polymer properties for manipulating the 3HHx mole fraction of P(3HB-co-3HHx) by controlling PhaJ translation.

Carbon-based and iron-based materials have been widely reported as effective promoters in biogas fermentation due to the promotion of electron transport. However, the effect of these materials, especially in combination, on short-chain fatty acids (SCFAs) production has been scarcely reported. In this study, the production of short-chain fatty acids (SCFAs) from green cabbage waste was promoted by adding biochar (BC) and biochar-supported zero-valent iron (BC@ZVI). The underlying mechanisms, focusing on metabolic pathways and electron transport, were subsequently investigated through metagenomic analysis. The optimal SCFAs yields were achieved with BC (5 g·L⁻1) and BC@ZVI (15 g·L⁻1). While BC notably enhanced n-butyrate production (89.4-fold), BC@ZVI balancedly promoted acetate and n-butyrate. Metagenomics revealed that BC@ZVI's superiority stemmed from its enhanced ability to enrich functional microbes and facilitate electron transfer. Metagenomic analysis revealed that BC@ZVI enriched Sphaerochaeta and Herbinix, which could participate in the direct interspecies electron transfer process. The abundance of almost all functional enzymes involved in carbohydrate hydrolysis and the synthesis of acetate and n-butyrate were remarkably increased by BC@ZVI. BC and BC@ZVI lead to a notable enrichment of conductive pili genes, including pilB, pilC, and pilM. BC@ZVI enriched both conductive pili and c-type cytochromes, which could be considered a more effective selection than BC. Notably, BC@ZVI was more effective than BC in stimulating n-butyrate-type fermentation, significantly shortening the lag phase and the overall fermentation cycle, thereby exhibiting better comprehensive performance, enhancing pH buffering capacity, and strengthening electron transfer and substrate hydrolysis. The results proved the potential of BC@ZVI in SCFAs fermentation and deciphered the underlying mechanisms, which provided a new perspective to promote resource recovery of organic waste by anaerobic system.

Pseudomonas aeruginosa poses a significant threat in clinical settings, acting as a major causative agent of bacteremia, particularly in immunocompromised patients. Intrinsic resistance of this bacterium necessitates the urgent need for novel anti-Pseudomonas agents. Current therapeutic strategies are becoming increasingly inadequate, emphasizing the importance of screening studies aimed at discovering new antimicrobials that can effectively target this resilient bacterium. In this context, the exploration of herbal remedies presents a promising avenue for the development of effective antimicrobial agents. Many herbs possess bioactive compounds with documented antimicrobial properties, which could serve as potential lead substances in the quest for new treatments against P. aeruginosa. In the current study, the effect of the aqueous extract of 38 plant tissues, which have been introduced as an antimicrobial plant in the available publications, was investigated on P. aeruginosa. This study was done on a standard strain which is known as causative agent of bacteremia to find new avenues against P. aeruginosa bacteremia. Extracts from flower buds of S. aromaticum, flower of P. granatum L. var. pleniflora, and fruit of R. coriaria were found as effective against P. aeruginosa. Combination effect of these extracts was primarily evaluated by double well synergy test, and it was found that P. granatum and R. coriaria extracts may have additive or synergistic antimicrobial effect. More evaluations were performed via checkerboard assay. Fractional inhibitory concentration index (FICI) was calculated as 0.84 which fall within the additive range (0.5 < FICI ≤ 1). These results suggest that the combination of P. granatum and R. coriaria extracts can provide a promising natural mixture with enhanced antimicrobial efficacy to treat P. aeruginosa bacteremia. So, it can be concluded that mixed extract is a valuable source of natural anti-Pseudomonas compounds which can be subjected for further studies regarding toxicity and formulation.

C-Phycocyanin (C-PC), a fluorescent photosynthetic protein derived from cyanobacteria, is used in the food, cosmetic, pharmaceutical, and biotechnology industries. Various cyanobacterial sources of C-PC have been studied to harness its biological functions such as antimicrobial, antioxidant, anticancer, and anti-inflammatory properties. Phormidium sp. A02 isolate from the Indian coast was cultured in a mixotrophic static environment to determine the effect of various bioprocess parameters like culture medium and light (photoperiod, light intensity, and light color) on biomass productivity and C-PC content. The C-PC from Phormidium sp. A02 can be used in the food and cosmetic industry as an alternative to synthetic chemical colorants. Carbon-mediated metabolic engineering of C-PC in Phormidium sp. A02 using Guillard's F/2 seawater medium supplemented with carbon sources like glucose, sucrose, glucose + peptone, and sucrose + peptone was carried out to determine its growth and C-PC enhancement efficiency. Sucrose + peptone with C/N ratio 4.76 increased Phormidium sp. A02 biomass productivity (0.197 ± 0.02 g dry weight L^-1 day^-1) by twofold compared to the autotrophic control (0.105 ± 0.01 g dry weight L^-1 day^-1). An analysis of C-PC content enhancement with glycerol supplementation showed that 0.9 g of glycerol L-1 was the optimal concentration. Higher biomass productivity (0.176 ± 0.01 g L^-1 day ^-1) was observed in photoperiods of 8/16 h light/dark and higher C-PC content (69.91 ± 4.86 mg g^-1) at lower light intensity in Phormidium sp. A02 under mixotrophic conditions. A two-phase static culture strategy was developed, beginning with 5 days of initial biomass production under white light, followed by 3 days of C-PC enhancement under monochromatic light. The dry biomass production in sucrose + peptone under white, green, and red light was similar in our two-phase static culture strategy, averaging 0.27 g L^-1. In contrast, red light induction increased C-PC more than other lights and by 6.5-fold (52.30 ± 0.002 mg g^-1) over a control with white light (7.76 ± 0.58 mg g^-1). C-PC had thermal stability up to 55 °C, pH stability up to 4.00 and a purity of 0.69. Phormidium sp. A02 cultured in a closed system under bioprocess strategies such as red-light induction, glycerol supplementation, and metabolism switchover could enhance C-PC and make it a viable culture technique.

Anaerobic ammonium-oxidizing (anammox) bacteria play a crucial role in biogeochemical nitrogen cycling and have been applied to wastewater treatment as a revolutionary nitrogen removal technology. Despite the successful application of anammox technology in engineering, our understanding of anammox bacteria in terms of their physiological and biochemical characteristics remains the tip of the iceberg, and challenges mainly arise from their slow growth rates and the absence of pure cultures. The development of enrichment cultures, particularly through membrane bioreactors, is important in addressing these challenges. In this review, we highlight the key factors that are vital for optimizing planktonic cell growth and preventing cell aggregation, i.e., calcium and magnesium concentration, oxygen level, and solids retention time, and propose the involved regulation strategies which help improve our understanding of the ecology of anammox bacteria and their competitive advantages, particularly in nitrogen-limited environments. Then, insights into the unique cellular structures of anammox bacteria (including anammoxosome and their distinct lipid membranes) and the complex metabolic pathways involving unique nitrogen intermediates were discussed, partially based on anammox planktonic cells. Finally, recent advances pertaining to non-traditional growth conditions and novel applications, such as ladderane lipid biosynthesis, extracellular polymeric substance production, and electro-anammox processes are discussed, underscoring their potential in innovative bioresource utilization beyond wastewater treatment. This review provides an in-depth understanding of planktonic cultivation techniques, growth dynamics, and biochemical characteristics of anammox bacteria, and highlights promising avenues for future research and application of valuable anammox bacteria resources, propelling their application in both ecological and engineered systems.