Bioresource Technology最新文献

A continuous-flow partial nitrification granular sludge (PNGS) coupled Anammox system was constructed for mature landfill leachate (MLL) treatment. Stable NO₂^–-N accumulation was achieved with NH₄⁺-N to NO₂^–-N transformation ratio (NTR) of 98–100 % with influent NH₄⁺-N ranged from 342 ± 29 to 1106 ± 20 mg/L. When treating MLL, particular acyl homoserine lactones (AHLs), cyclic dimeric guanosine monophosphate (c-di-GMP) concentration significantly increased and more extracellular polymeric substances (EPS) were secreted, which adsorbed refractory organics and embedded SiO₂ derived from MLL for granulation. A strong and positive correlation was found between PNGS average diameter and EPS, indicating that AHLs and c-di-GMP may play a significant role in the formation and evolution of PNGS via regulating EPS secretion. The PNGS/Anammox system could remove COD and nitrogen simultaneously under different MLL loadings, with COD and total inorganic nitrogen removal efficiency of 28 ± 5 %-71 ± 2 % and 66 ± 2 %-89 ± 1 %, respectively.

Excessive nitrogen release during composting poses significant challenges to both the environment and compost quality. Biological enhancement of humification and nitrogen conservation is an environmentally friendly and cost-effective approach to composting. The aim of this study was to develop a psychrophilic and thermophilic nitrifying bacterial consortium (CNB) and investigate its role in nitrogen transformation and humification during cow manure composting. Analysis revealed that CNB inoculation promoted microbial proliferation and metabolism, significantly increased the number of nitrifying bacteria (p < 0.05), and elevated the activity of nitrite oxidoreductase and nxrA gene abundance. Compared to the control, CNB inoculation promoted the formation of NO₃^–-N (77.87–82.35 %), while reducing NH₃ (48.89 %) and N₂O (20.05 %) emissions, and increased humus content (16.22 %). Mantel analysis showed that the higher abundance of nitrifying bacteria and nxrA facilitated the nitrification of NH₄⁺-N. The improvement in nitrite oxidoreductase activity promoted NO₃^–-N formation, leading to increased humus content and enhanced compost safety.

The presence of refractory lignocellulose presents a significant challenge in green waste (GW) composting. This research applied both a conventional iron-based Fenton-like process (with a Fenton-like reagent composed of 1.0 % Fe₃O₄ nanoparticles and 1.0 % H₂O₂) and three modified iron-based Fenton-like processes (with a Fenton-like reagent composed of 1.0 % Fe₃O₄ nanoparticles and 1.0 % oxalic acid/1.0 % sodium percarbonate/0.5 % Phanerochaete chrysosporium) in GW composting to systematically assess their impacts on lignocellulose degradation during GW composting. The results revealed that iron-based Fenton-like process modified sodium percarbonate exhibited the most significant effects on lignocellulose degradation. Compared with control, degradation rates for lignin, cellulose, and hemicellulose increased by 49.8 %, 39.3 %, and 26.2 % (p < 0.05), respectively. Furthermore, this process enhanced the relative abundance of bacterial communities linked to lignocellulose degradation, particularly Firmicutes and Bacteroidota. These findings offer valuable insights into optimizing GW composting, understanding reactive oxygen species dynamics, and the application of iron-based Fenton-like process.

Ecologically, interactions and contributions of microbiota generalists and specialists remain largely unexplored in remediation of deep-sea oil pollution. Herein, ecological and evolutionary characteristics of the two taxa were comprehensively investigated in restoration of oil-polluted sediment at deep-sea microcosm. Niche-specialized taxa exhibited rapid speciation rate, more complex network structure and highly interspecific mutualism. In contrast, generalists possessed higher richness but with poor local performance, as evidenced by higher extinction rate, lower stability, and more interspecific antagonism. Generalists were the primary oil degraders, while specialists acted as auxiliaries promoting degradation via production of biofilm and biosurfactant. Evolutionarily, the continuous transition from specialists to generalists insured the exclusion of generalist at a relatively constant level for ecological trade-offs. Collectively, the findings emphasize the importance of specialists in facilitating oil degradation by elucidating their vital roles in maintaining system stability and regulating microbial diversity during process, and offer valuable guidance for designing remediation plans.

As millions of tons of kraft lignin are being wasted, a potential application is to use its crosslinking reactions to build thermosetting bio adhesives. However, the crosslinking reactions between lignin molecules are not fully understood. The present study aims to elucidate the crosslinking reactions of the model lignin compound guaiacylglycerol-β-guaiacyl ether (GGE) via one-step hydroxymethylation/ amination with formaldehyde and diethylenetriamine (DETAM), or one-step glyoxylation/ amination with glyoxal and DETAM via liquid NMR techniques such as ¹H NMR, ¹³C NMR, 2D ¹H–¹³C, and ¹H–¹⁵N HSQC NMR. Specifically, the 2D ¹H–¹³C HSQC NMR spectra confirm the presence of –CH₂–NH– with a chemical shift of ¹H 2.6–3.6/¹³C 40–60 ppm, and the formation of methylene linkages via the crosslinking reaction. Also, the 2D ¹H–¹⁵N HSQC NMR spectra clearly detect the formation of amide and imine bonds at ¹H 7.8/¹⁵N 110 and ¹H 8.07/¹⁵N 121.5 ppm from the crosslinked GGE.

Design of Experiments (DoE), is a tool to explore relationships between factors and responses of a system. DoE and response surface methodology are increasingly used in different fields, but their application are limited in the valorization of residual biomass and agro-industrial by-products. Agro-industrial biomass residues can be eco-friendly converted into high-value compounds through bioprocesses. This approach identified key factors and predicted optimal conditions for enhancing microbial growth and the production of specific compounds or volatile classes. Lactiplantibacillus plantarum 4193 and Lacticaseibacillus paracasei 2243, were identified as the best starters while the production of methyl heptenone is influenced by fermentation time and pH. This out-turn in the generation of aromatically rich biomass, which can be utilised as a food ingredient or for the extraction of specific volatile compounds, and employed as flavouring agents. This study underlines the potential of fermentation in maximizing the value of unripe kiwi biomass.

4-hydroxymandelate is a high-value aromatic compound used in the medicine, cosmetics, food, and chemical industry. However, existing natural extraction and chemical synthesis methods are costly and lead to environmental pollution. This study employed metabolic engineering and directed evolution strategies for de novo 4-hydroxymandelate biosynthesis. Two key challenges were addressed: insufficient precursor supply and limited activity of crucial enzymes. Through gene overexpression and multi-level gene interference using CRISPRi, An Escherichia coli chassis capable of producing the key precursor 4-hydroxyphenylpyruvate and the titer reached 5.05 mM (0.91 g/L). A mutant clone was obtained, HmaS^V152G, which showed a 5.13-fold improvement in the catalytic rate. During fermentation, a high production of 194.87 mM (32.768 g/L) 4-hydroxymandelate was achieved in 76 h with a batch supply of glucose in a 5-L bioreactor. This study demonstrated the great potential of biosensors in protein engineering and provides a reference for large-scale production of other high-value aromatic compounds.

This study presents a novel approach to sustainable aquaculture by integrating biofloc technology (BFT) with a compact down-flow hanging sponge (DHS) reactor. The integrated BFT-DHS system effectively removed nitrogen compounds while maintaining ammonia–nitrogen (NH₄⁺-N) concentrations below 1 mg-N L^-1 without water exchange. Application of this system in a tank bred with juvenile Oreochromis niloticus showed a high NH₄⁺-N removal rate of up to 97 % and nitrite (NO₂^– −N) concentrations were maintained at 0.1 ± 0.1 mg-N L^-1. Microbial analysis revealed Gordonia as the predominant genus in the biofloc contributing to heterotrophic nitrification, while the Peptostreptococcaceae family dominated the DHS reactor. Heterotrophic nitrification seemed to be the primary process for enhanced nitrogen removal. Pathogenic bacteria, Vibrio sp. was absent throughout the study. This study highlights the potential integration of BFT and DHS system for sustainable aquaculture practice with effective nitrogen removal.

Predator-prey interactions play a crucial role in maintaining ecological balance and possibly provide inspiration for strategies to mitigate environmental changes such as harmful algal blooms (HABs). To this end, this study aims to develop a novel strategy to mitigate HABs based on predator–prey interaction, i.e., Daphnia magna and Microcystis aeruginosa interaction. Bio-compounds (urea and 9-octadecenamide) produced by D. magna when encounter M. aeruginosa, were identified, particularly with urea promoting the aggregation of M. aeruginosa. Then, a novel adsorbent against HABs was synthesized by integrating bio-compounds of urea, and its effectiveness in removing M. aeruginosa was demonstrated. Notably, the adsorbent displayed a high removal efficiency of 99.25 % within 6 h. Our eco-friendly strategy holds promise for controlling HABs, representing the successful application of biomimicry principles.