Bioprocess and Biosystems Engineering最新文献

Aflatoxin B1 (AFB1), the most toxic mycotoxin produced by some Aspergillus species, is commonly found in agricultural products, especially grains, and poultry feeds. Enzymic degradation is considered to be the most promising detoxification method, because it is efficient, safe and causes minimal damage to the nutritional quality of treated foods. In this study, a recombinant manganese peroxidase (Il-MnP1) and a recombinant dye-decolorizing peroxidase (Il-DyP4) from Irpex lacteus F17 were used to degrade AFB1, either individually or in combination. The degree of degradation of AFB1 by the combined enzymes of Il-MnP1 + Il-DyP4 was higher than that of either enzyme acting alone. The half-life of AFB1 degradation by the combined enzymes was lower than that of either enzyme alone. Further analysis of the degradation products indicated that the use of the combination of Il-MnP1 + Il-DyP4 to degrade AFB1 resulted in a greater number of metabolites, including five new degradation products with the chemical formulas, C₁₆H₁₀O₈, C₁₅H₁₀O₅, C₁₅H₁₀O₆, C₁₆H₁₀O₇, and C₁₆H₈O₇. The system of Il-MnP1 + Il-DyP4 contained multiple enzyme activities that could act on different toxic sites of AFB1, thereby producing metabolites with lower toxicity and carcinogenicity, which was consistent with the results of the Ames test. These findings suggest that using the combined enzymes to convert AFB1 into non-toxic products is a good strategy for detoxifying contaminated foods and feeds.

Herein, we explored an effective method for preparing silver nanoparticles (Ag NPs)-coated antibacterial silk fabrics. In particular, using amino acids and cellulose from silk as reducing agents and silver nitrate as a precursor, Ag NPs were synthesised in situ on the surface of silk without requiring additional reducing agents and catalysts. The surface morphology and chemical composition of the involved samples were characterised using techniques such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Notably, silk and silk precursors (silkworm cocoons, silk fibers and sericin) could be used for in situ Ag NPs synthesis. Furthermore, the antibacterial properties of the samples were evaluated against Escherichia coli-a Gram-negative bacterium-as a model, demonstrating an impressive antibacterial rate of up to 99.91%. In addition, we investigated the water absorption behaviour of the samples at 25 °C by assessing their moisture regain, water retention value and vertical wick height. The results indicated that the Ag NPs coating did not damage the water absorption performance of the involved silk. Finally, we compared the fabric performance before and after treatment using a universal testing machine and colorimeter. The results showed that the mechanical properties of the fabrics with the Ag NPs coating did not substantially change with treatment, but the fabrics became more yellowish. Overall, this research has notable application potential in the field of antibacterial fabrics.

Animal manure is considered to have great potential for phosphorus (P) recovery due to its high P content, while P recovery is limited by the transfer of P from the solid phase to the liquid phase. The conventional dissolution process by adding chemical acid reagents is not economically feasible for animal manure. This study used food waste (FW) as a co-substrate for the anaerobic fermentation of pig manure (PM) to achieve the release of P. The operational parameters were optimized, and the mechanisms of acidification and P release were further studied. The results showed FW promoted lactic acid production and rapid acidification. As FW increased from 0 to 80%, the concentrations of lactic acid rose from 0.12 ± 0.04 to 11.95 ± 1.37 g/L, with pH decreasing from 7.55 to 4.43. The ratio with FW/PM = 1:2 was the optimal condition, which led to the highest soluble phosphate concentration (350.39 ± 8.59 mg/L) in 72 h, with a TP release rate of 74.24 ± 1.81%. Multiple regression analyses established key relationships to predict pH changes in the reactor.

Lipases are one of the ubiquitous enzymes that belong to the hydrolases family and have a wide variety of applications. Cold-active lipases are of major attraction as they can act in lower temperatures and low water conditions because of their inherent greater flexibility. One of the novel applications of lipase is the enrichment of ω-3 polyunsaturated fatty acids (PUFA) in plant and fish oils. This study is aimed at the isolation and identification of cold-active lipase producing bacterium from marine sources, preliminary optimization of medium constituents and conditions, purification of lipase using chromatographic techniques, biochemical characterization, and ultimately the exploration of its application in the enrichment of ω-3 PUFA in flax seed oil. Psychrobacter alimentarius ILMKVIT was identified as the potential cold-active lipase producing bacterium based on its lipolytic activity in rhodamine B agar, titrimetric, and p-nitrophenyl palmitate (p-NPP) assays. One factor at a time (OFAT) analysis, revealed, an incubation time of 4.5 days, alkaline pH of 9, the temperature of 25 °C, peptone, and yeast extract as nitrogen sources, olive oil as inducer sources, 1% inoculum size, and NaCl as mineral sources as optimum production medium constituents and conditions for lipase production. Lipase purification was achieved by ion exchange and gel-filtration chromatography with a 9.27% yield and 37.51-fold purification. Biochemical characterization reported that the lipase is cold-active, alkaline, enhanced by Fe³⁺ metal ions, and tolerant to organic solvents, detergents, and inhibitors. P. alimentarius ILMKVIT lipase-hydrolysis followed by urea complexation of flax seed oil resulted in the enrichment of ω-3 PUFA, especially α-linolenic acid (ALA). Hence, the novel cold-active lipase from P. alimentarius ILMKVIT could be used to enrich ω-3 PUFA in flax seed oil and developed further as a prominent nutrient supplement for health benefits.

Low-temperature ethylenediamine (EDA)/urea pretreatment had been demonstrated to be an efficient pretreatment method for enzymatic hydrolysis and bioethanol production. For high-value utilization of the third main components of lignocellulosic biomass, the physicochemical structure characteristics and biological activities of low-temperature EDA/urea pretreated lignin (EUL) were comprehensively investigated in the present study. The results demonstrated that the pretreatment process facilitated the depolymerization of lignin, resulting in notable reduction in molecular weight and polydispersity index from 2.32 to 1.42 kg/mol and 1.44 to 1.20, respectively. The EDA/urea pretreated lignin (EUL) exhibited enhanced ultraviolet absorption capacity and the most significant DPPH radical scavenging and inhibition of Staphylococcus aureus in comparison to the primary lignin (PL) and the NaOH pretreated lignin (NL). Enhanced physicochemical characteristics and biological activities of EUL make it more suitable to be developed as sunscreen ingredient or antioxidant and antimicrobial agent in food preservation and conservation.

Heavy crude oil reserves are characterized by their high viscosity and density, largely due to significant quantities of asphaltenes. The removal of asphaltene precipitates from oil industry installations is crucial, as they can contaminate catalysts and obstruct pipelines. Therefore, this study aimed to bio-transform heavy oil asphaltenes into smaller molecules using the yeast Yarrowia lipolytica, known for its ability to efficiently degrade hydrophobic substrates. For this purpose, asphaltenes were extracted from crude oil samples, and yeast growth was assessed in a mineral medium containing 2, 5, or 10 g L^-1 of asphaltenes. After 168 h of incubation, liquid-liquid extraction was conducted on samples from the Yarrowia lipolytica growth medium using chloroform. The extracted fractions were then quantified by gas chromatography. The results indicated that the yeast could utilize the asphaltenes as a carbon source for growth, though there was a delay in growth compared to the control (glucose as the carbon source), with a maximum biomass concentration of 2.26 g L^-1 achieved at 144 h. From the experimental design, it was determined that a higher concentration of aromatic compounds was achieved under the conditions of 115 rpm, 2 g L^-1 of asphaltenes, and 0.5 g L^-1 of cell inoculum. Conversely, to obtain a higher concentration of saturated compounds, the optimal conditions were 160 rpm, 5 g L^-1 of asphaltenes, and 1.0 g L^-1 of cell inoculum. Molecular docking results indicated that asphaltenes have a high affinity for cytochrome P450, laccase, and Lip2, with interactions observed with their catalytic triads, suggesting a significant role for these enzymes in asphaltene bioconversion.

The transition towards sustainable bioprocesses requires renewable feedstocks to reduce dependency on finite resources. While plant-based feedstocks offer significant potential, their complex composition poses new challenges. The microorganisms often exhibit polyauxic growth when presented with multiple carbon sources simultaneously, consuming them in a distinct order according to their carbon source preferences. The traditional investigation of polyauxic growth involves laborious sampling and offline analysis, hindering high-throughput screenings. This study introduces an efficient method for identifying carbon source consumption and their order of metabolization by various microorganisms using the respiration activity monitoring system (RAMOS) in shake flasks. As aerobic carbon metabolization and oxygen consumption are strictly correlated, the characteristic phases of polyauxic growth are visible in the oxygen transfer rate (OTR) and can be assigned to the respective carbon sources. An extended 16-flask RAMOS enables real-time monitoring of microbial respiration on up to seven carbon sources and one reference cultivation simultaneously, thus providing crucial insights into their metabolization without extensive sampling and offline analysis. The method's accuracy was validated against traditional high-performance liquid chromatography (HPLC). Its applicability to both fast-growing Escherichia coli (investigated carbon sources: glucose, arabinose, sorbitol, xylose, and glycerol) and slow-growing Ustilago trichophora (glucose, glycerol, xylose, sorbitol, rhamnose, galacturonic acid, and lactic acid) was demonstrated. Additionally, it was successfully applied to the plant-based second-generation feedstock corn leaf hydrolysate, revealing the bioavailability of the included carbon sources (glucose, sucrose, arabinose, xylose, and galactose) and their order of metabolization by Ustilago maydis.

This research provides an important approach for low-nitrogen wastewater treatment through anaerobic ammonium oxidation (Anammox), and Anammox granule sludge (AnGS) in the Upflow. Blanket Filter Anammox (UBFA) system through shortening the hydraulic retention time was successfully cultivated. The percentage of medium granules (1.0-2.0 mm) with the highest Anammox activity increased from 0 to 28.5%, and the proportion of flocs (0-200 μm) reduced from 84.5% to 17.6%. Through the multidimensional analysis of AnGS, the relationship between AnGS and EPS secretion, low SVI, high PN/PS, multiple filamentous bacteria, and AnAOB were explored. Microelectrode tracing tests demonstrated that the main anammox reaction active layer was 0-1500 μm, and the highest activity was observed at 200-400 μm, whereas denitrification activity and N₂O production were mainly distributed in the granules deep layer of 1500-2500 μm. The research showed that Candidatus Brocadia and Candidatus Kuenenia were the predominant anammox species in the UBFA system, while the abundance of AnAOB was higher in medium granules.

The purpose of this review is to gain attention about intro the advanced and green technology that has dual action for both clean wastewater and produce energy. Water scarcity and the continuous energy crisis have arisen as major worldwide concerns, requiring the creation of ecologically friendly and sustainable energy alternatives. The rapid exhaustion of fossil resources needs the development of alternative energy sources that reduce carbon emissions while maintaining ecological balance. Microbial fuel cells (MFCs) provide a viable option by producing power from the oxidation of organic and biodegradable chemicals using microorganisms as natural catalysts. This technology has sparked widespread attention due to its combined potential to cleanse wastewater and recover energy. The review presents a complete examination of current advances in MFCs technology, with a focus on the crucial role of anode materials in improving their performance. Moreover, different anode materials and their nanoscale modifications are being studied to boost MFC efficiency. This current review also focused on the effects of surface modifications and different anode compositions on power generation and system stability. It also investigates the electrochemical principles behind these enhancements, providing insights into the economic potential of MFCs. MFCs provide a long-term solution to energy and environmental issues by addressing both wastewater treatment and energy production.

Levilactobacillus brevis KCL010 was fermented in a simple medium containing 8% (w/v) of rice bran extract. We modified the carbon, nitrogen, and initial pH conditions using 10 g/L of sucrose, 10 g/L of yeast extract, and 5.0 of pH, respectively. To minimize the pH increase due to decarboxylation, we fermented 100 mL of modified synthetic medium containing citrate-phosphate buffer (CPB, pH 5.0) of 25-200 mM in 250 mL Erlenmeyer flasks. After 72 h of fermentation with 50 mM CPB, the maximum GABA concentration and conversion efficiency were 3.42 g/L and 22.39%. Furthermore, the potential α-glucosidase inhibitory activity, MTT assay, and oil red O staining were determined by fermented extracts of L. brevis KCL010. At the highest concentration of 500 μg/mL, the α-glucosidase inhibition percentages for non-fermented rice bran (NFRB), rice bran fermented by L. brevis (RBFL), and GABA (analytical standard) extracts were 55.03%, 58.37%, and 59.48%, respectively. All extracts exceeded 80% viability, suggesting that there was no cytotoxic to 3T3-L1 adipocytes. The rice bran fermented by L. brevis (RBFL) extract shows a high inhibition of lipid accumulation by 29.33% compared to those of extracts.