Bioresource Technology最新文献

Hydrothermal carbonization (HTC) is a promising thermochemical process for converting biomass into value-added products such as hydrochar. Most HTC research is conducted in batch reactors due to their simplicity, resulting in a lack of studies on continuous operations. Batch reactors have limitations primarily related to a smaller throughput preventing further process development. Continuous reactors, by contrast, offer significant throughput, but design and performance remain largely underexplored. This study investigates the HTC of glucose in both batch and continuous reactors under near-isothermal reaction conditions, with a focus on understanding reaction kinetics. Batch HTC was conducted at 230 °C by injecting a 10 g/L mixture of glucose and water. With use of a sophisticated injection port, biomass reactants were rapidly heated to reaction temperature, allowing for near isothermal reaction conditions. Our approach overcomes the long-time delay resulting from heating a heavy steel reactor. A continuous HTC system was designed, fabricated, and tested with a throughput of 0.30 L/min. The reactor is configured as a baffled plug flow reactor consisting of three main sections: biomass feeding and, the continuous HTC reactor zone, and an energy recovery and depressurization unit. A kinetic model was developed from batch experiments and applied to predict the performance of a continuous HTC reactor using the segregation model. The predicted glucose conversions were 94.80 % for the continuous reactor and 96.30 % for the batch reactor at the same mean residence time of 13.25 min.

The deep-sea-derived Streptomyces atratus SCSIO ZH16 is a promising host for producing nanomole-level anti-tuberculosis ilamycins. However, limited research on regulating the ilamycins biosynthetic gene cluster (BGC) has hindered industrial production. Our previous study found that nitrogen metabolism-related genes were upregulated in strains with enhanced ilamycins production. Since amino acids from nitrogen metabolism are key precursors, we aimed to optimize ilamycins production by balancing BGC expression and nitrogen metabolism. Using RNA-seq and hierarchical clustering, we identified the native promoter P₂₀₆₀₅ and its modified version P_20605-400, which regulate the positive regulator IlaB in ilamycins BGC. To synchronously boost ilamycins synthesis and precursor supply, we analyzed P₂₀₆₀₅'s function via bioinformatics and validated it using an indigoidine biosynthetic model. The engineered strain ΔilaR::P_20605-400-ilaB::P_ermE*-phoP achieved over a dozen-fold increase in ilamycins yield. Fermentation was successfully scaled up in 5-L and 500-L bioreactors, reaching titers of 2,546.4 mg/L and 1,993.9 mg/L, respectively, significantly surpassing previously reported yields. This study highlights the industrial potential of ilamycins and provides insights into enhancing peptide compound production in Streptomyces.

Upcycling biowaste into useful biochemicals, including medium-chain fatty acids (MCFAs) represents a crucial node in the transition toward a circular economy. However, the output and stability of anaerobic microbiomes for MCFAs production are strongly anchored on the effective inhibition of competing pathways, including methanogenesis, while stimulating the growth of bacteria producing MCFAs. Here, we proposed a mixotrophic chain elongation (CE) concept for producing MCFAs from food waste by exploring carbon monoxide (CO) as a methanogenic inhibitor. Our findings suggest that CO supplementation at an optimum partial pressure (P_CO) of 0.25 atm enhances carbon flux toward MCFAs production instead of methanogenesis, resulting in the highest MCFAs concentration observed in this study (10.4 ± 0.4 g-COD/L), with n-caproate as the predominant MCFA. Experiments with CO as the sole substrate demonstrated that the supplied CO could be converted into intermediates such as acetate and ethanol that potentially augmented MCFAs synthesis. Homoacetogens and chain elongators, notably Megasphaera spp. and members of the Lachnospiraceae family were enriched in the P_CO of 0.25 atm system, forming a putative metabolic network to promote CE. These findings provide insights into valuable MCFAs biosynthesis from biowaste.

Lignin has attracted attention in water treatment due to its extensive sources, complex structure, environmental friendliness, and functionality. Mannich modification is an effective method for enhancing the lignin's active sites, but it typically requires high temperatures and long reaction times, which limits its scalability for practical application. This study presents a simple, one-step Mannich reaction at room temperature for synthesizing aminated lignin (NAL) with high yield and ultra-high nitrogen content (17.34 %), using triethylenetetramine (TETA) as a modifier. The method effectively leverages TETA's symmetrical polyamine properties and glutaraldehyde (GDA)'s dual crosslinking functionality. Density functional theory (DFT) revealed that the potential and the discrepancy of reactive groups' energy gap (E_gap) were the key factors influencing the synthesis. The as-designed NAL exhibited excellent adsorption capacities of 1088.71 mg/g and 909.09 mg/g at 318 K for Hg(II) and Congo red (CR), respectively, that were superior to most reported modified lignin-based adsorbents. NAL also demonstrated robust resistance to ion interference, good reusability, and practical applicability. Notably, the adsorption performance of CR in the Hg(II)-CR binary system was enhanced with an adsorption capacity ratio (R_q) reaching 2.09. XPS, Zeta potential, and DFT calculations revealed that NAL's superior adsorption properties result from multiple interactions, including coordination, π-π interactions, hydrogen bonding, and electrostatic forces. Overall, NAL represents a green and highly effective material for environmental remediation with significant research and practical application value.

Efficient bioconversion of acetate-rich lignocellulosic biomass into value-added chemicals remains a major challenge due to the toxicity of acetic acid. In this study, we developed an acid-tolerant Issatchenkia orientalis strain (IoDY01H) capable of producing 3-hydroxypropionic acid (3-HP), a key bioplastic precursor, from glucose, xylose, and acetate. Using a Cas9-based genome editing system with a hygromycin B resistance marker, we introduced heterologous genes encoding xylose utilization and β-alanine-based 3-HP biosynthetic pathways into the I. orientalis genome. Metabolomic analysis revealed that acetate supplementation redirected metabolic flux toward amino acid and lipid metabolism while reducing tricarboxylic acid (TCA) cycle intermediates. Acetate enhanced 3-HP production; however, the accumulation of β-alanine suggests that the activity of β-alanine-pyruvate aminotransferase may have been limited under acidic conditions. Consistent with this, fermentation at pH 5.5 resulted in higher 3-HP titers than at pH 3.5. Using pretreated hemp stalk hydrolysate as a feedstock, the engineered strain achieved a 3-HP titer of 8.7 g/L via separate hydrolysis and fermentation (SHF), outperforming simultaneous saccharification and fermentation (SSF). These findings demonstrate the feasibility of producing 3-HP from acetate-rich biomass using engineered non-conventional yeast and highlight I. orientalis as a promising microbial chassis for industrial bioconversion.

A highly efficient denitrifying bacterial strain (Acinetobacter sp. LF10) was isolated in this study, strain LF10 efficiently removed ammonium (98.02 ± 0.43 %), nitrate (90.35 ± 1.68 %), and nitrite (86.84 ± 2.41 %) from aquatic systems through coordinated assimilatory and dissimilatory nitrate reduction pathways coupled with ammonium assimilation. Compared with the traditional denitrification process, strain LF10 has the potential to reduce greenhouse gas (N₂O) emissions. Strain LF10 not only has strong temperature adaptability (15-35 ℃), but also has the advantage of maintaining a high ammonia nitrogen removal rate under low C/N conditions. Strain LF10 has demonstrated great potential in the treatment of aquaculture wastewater. LF10 can maintain strong competitiveness in biofilters and significantly enhance the nitrogen removal performance of biofilters under normal temperature (31.0 ± 2.4 ℃) and low temperature (15.0 ± 0.3 ℃) conditions. The average total nitrogen removal rates were 94.67 ± 0.64 % and 84.72 ± 17.03 %, respectively. These attributes position LF10 as a highly promising candidate for nitrogen removal in aquaculture wastewater treatment, offering considerable potential for the resource utilization of wastewater in sustainable aquaculture practices.

This study investigates the composition of aqueous phase (AP) from 24 HTL trials of two different municipal sewage sludge (MSS) samples, using homogeneous (Na₂CO₃, Li₂CO₃, K₂CO₃, Ba(OH)₂) and heterogeneous (Fe₂O₃, CeO₂, NiO/MoO₃, MoS₂, Ni/NiO, SnO₂, FeS) catalysts. Principal Component Analysis (PCA) was applied to assess the influence of feedstock and catalyst on AP composition i.e. formation of water soluble components. MSS1-derived AP showed a higher proportion of oxygenated aliphatics (13.9-33.7 %), while MSS2 had elevated N-heterocyclic aromatics (19.6-43.3 %). Homogeneous catalysts increased concentration of phenols (up to 26.3 %) and carboxylic acids, with K₂CO₃ almost doubling the carboxylic acid derivatives. Heterogeneous catalysts affected nitrogen and total organic carbon contents. Whereas Fe₂O₃ increases the aliphatic N-heterocycles from 20.6 % to 30.2 % (MSS1) and from 12.7 % to 21.0 % (MSS2), FeS strongly decreases the aromatic hydrocarbons from 9.5 % to 1.1 % (MSS1). PCA analysis confirmed distinct clustering patterns based on the interactions of the feedstock and catalyst, highlighting their synergistic effects. Phenol and cresol were present in the highest concentrations for both sludge, ranged up to 15.6 % and 15.4 % for MSS1 and 12.6 % and 12.9 % for MSS2, respectively. Among the oxygenated aliphatics the most abundant were cyklopenten-1-one, ethanone and their derivatives. N-heterocyclics were represented by a broad mix of pyrazine, pyridine, pyridinole, pyrrolidine, piperidine and their derivatives. The study demonstrates that feedstock properties significantly affect the AP composition, additionally it highlights the role of catalysts applied. These findings provide key insights into optimizing HTL conditions for industrial-scale applications and supporting effective AP by-product management strategies.