Bioresource Technology最新文献

Organic carbon can influence nitrogen removal during the anaerobic ammonia oxidation (anammox) process. Propionate, a common organic compound in pretreated wastewater, its impacts on mixotrophic anammox bacteria and the underlying mechanisms have not been fully elucidated. This study investigated the core metabolism and shift in behavior patterns of mixotrophic Candidatus Brocadia sapporoensis (AMXB) under long-term propionate exposure. Genome-resolved metagenomic analysis revealed that AMXB could convert nitrate generated by anammox bacteria to ammonium via the DNRA pathway, leveraging propionate as an electron donor. This recycled ammonium was then used to sustain the anammox process, thereby enhancing nitrogen removal efficiency. Notably, AMXB grew more efficiently than DNRA and denitrifying bacteria due to its more energy-efficient propionate metabolic pathway. This finding suggests that AMXB, as a mixotrophic anammox bacterium, has a competitive advantage in nitrogen metabolism in low C/N wastewater, contributing to efficient nitrogen removal.

Invasive Spartina alterniflora poses a significant threat to coastal wetland ecosystems. This study investigated the role of sulfur (S) in facilitating the invasion of S. alterniflora in cadmium (Cd)-contaminated coastal wetlands by greenhouse-control-experiment. Results demonstrate that increased S deposition significantly enhanced the formation of acid-volatile sulfur in sediments, thereby reducing the bioavailability of Cd to plants by 41%. Additionally, S supplementation improved plant nutrient uptake and stress tolerance by increasing the C/N ratio and the concentrations of essential mineral elements. These physiological and biochemical changes, including enhanced photosynthesis, increased carbohydrate storage, and improved antioxidant capacity, ultimately contributed to increased shoot and root biomass production by 15% and 31% respectively, and the competitive ability of S. alterniflora. The findings of this study highlight the critical role of S in promoting the invasion of S. alterniflora. Effective strategies can be developed to control the spread of S. alterniflora and protect coastal ecosystems.

Enhanced microbial remediation represents a promising technique for the removal of polycyclic aromatic hydrocarbons (PAHs). However, high-efficiency remediation agents remain limited, including microbial resources and remediation materials. In this study, a novel strain of Pseudomonas xizangensis S4 was isolated from plateau lake sediment, exhibiting a fluoranthene degradation rate of 41.90 % at 50 ppm within 7 d. The key degradation genes identified through genomic and transcriptomic analyses included ndmC, dmpK, dmpB, and dmpH. The metabolites detected via GC-MS analysis were biphenyls, parabens, and phthalate esters. Based on the above results, the degradation mechanisms of fluoranthene were deduced. Furthermore, an efficient remediation agent was developed, utilizing potassium humate-modified biochar to immobilize bacterial cells. The developed remediation agent enhanced the removal efficiency by 16.71 % compared to the single strain. Thus, the application of potassium humate-modified biochar for the immobilization of P. xizangensis S4 represents a promising method for the remediation of PAH-contaminated soil.

To effectively address the contamination caused by antibiotic misuse, this study was conducted to enhance the removal of amoxicillin (AMX) and penicillin sodium (PEN) by incorporating black soldier fly larvae (BSFL). The results showed that BSFL increased the degradation rates of AMX and PEN to 71.00 % and 80.89 %, respectively, and shortened their half-lives to 238 h and 160 h. Proteobacteria (26.2 %-82.0 %), Firmicutes (13.3 %-54.0 %), Acinobacteriota (2.1 %-23.4 %), and Bacteroidota (1.3 %-10.1 %) were the intestinal dominant microorganisms during transformation. Five bacteria with β-lactam antibiotic resistance in the BSFL gut were isolated, among which Morganella morganii demonstrated strong antibiotic tolerance and high removal rates of AMX and PEN in both in vitro and in vivo experiments, ranging from 58.99 % to 95.87 %. BSFL intestinal bacteria disrupted the quaternary pharmacophore of AMX and PEN, breaking them down into at least seven and five metabolites, respectively.

Pinene is a plant volatile monoterpenoid which is used in the fragrance, pesticide, and biofuel industries. Although α-pinene has been synthesized in microbial cell factories, the low synthesis efficiency has thus far limited its production. In this study, the cell growth and α-pinene production of the engineered yeast were decoupled by a dynamic regulation strategy, resulting in a 101.1-fold increase in α-pinene production compared to the control. By enhancing the mevalonate pathway and expanding the cytosolic acetyl-CoA pool, α-pinene production was further increased. Overexpression of the transporter Sge1 resulted in a redistribution of global gene transcription, leading to an increased flux of α-pinene synthesis. By optimizing the aeration flow rate in 3-L bioreactors, the α-pinene production reached 1.8 g/L, which is the highest reported α-pinene production in cell factories. Our research provides insights and fundamentals for the efficient synthesis of monoterpenoids in microbial cell factories.

Enhancing the passivation of heavy metals and increasing organic matter content during the composting of sewage sludge poses significant challenges for maximizing its utilization value. Results indicated that in the control, biochar, microbial agents and microbial agents-loaded biochar (BCLMA) groups, BCLMA addition led to a higher composting temperature, with increases of 17-62% in humic acid, 25-73% in germination index, and 30-35% in organic matter consumption. And the residual fraction of Cu, Zn, Cr and Cd were increased by 30%, 12%, 22% and 17%, respectively. Furthermore, BCLMA promotes community cohesion, robustness, and microbial nutrient cycling, and increases the relative abundance of heavy metals-degrading bacteria (Acinetobacter and Corynebacterium) and resistance genes. Structural equation model analysis revealed that heavy metal passivation is attributed to improved community cohesion and robustness, which facilitates the proliferation of heavy metal-resistant microorganisms. These results indicate that community robustness and cohesion are critical for mitigating the heavy metals bioavailability.

Miltiradiene serves as a pivotal precursor for the synthesis of numerous abietane-type diterpenes with important pharmacological activities. The endogenous mevalonate (MVA) pathway is tightly regulated in Saccharomyces cerevisiae, which limits the availability of precursors for the heterologous production of miltiradiene. In this study, the orthogonal isopentenol utilization pathway (IUP) was constructed and investigated for its adaptability with mitochondria and peroxisomes in S. cerevisiae for the synthesis of miltiradiene. Compartments combinatorial engineering was used to enhance precursor supply and miltiradiene synthesis, thereby elevating the production of miltiradiene to 146.1 mg/L in S. cerevisiae. Furthermore, an artificial multifunctional enzyme, tSmCPS-tSmKSL-PvPT, was constructed by mimicking the natural multifunctional enzyme to enhance the biosynthesis of miltiradiene in S. cerevisiae strain PCM-MT1, which is capable of producing 414.4 mg/L miltiradiene. Finally, the titer of miltiradiene was increased to 1.02 g/L by fed-batch fermentation in a 5 L bioreactor. This study broadens the application of the IUP in S. cerevisiae by integrating compartmentalization and artificial multifunctional enzymes for the synthesis of diterpenes.

The fermentation process in alcoholic beverage production converts sugars into ethanol and CO₂, releasing significant amounts of greenhouse gases. Here, Cupriavidus necator DSM 545 was grown autotrophically using gas derived from alcoholic fermentation, using a fed-batch bottle system. Nutrient starvation was applied to induce intracellular accumulation of poly(3-hydroxybutyrate) (PHB), a bioplastic polymer, for bioconversion of CO₂-rich waste gas into PHB. Grape marc, another by-product of wine production, was evaluated as a low-cost carbon source for the heterotrophic growth of C. necator, which was subsequently used as an inoculum for autotrophic cultures. The effect of agitation, CO₂ headspace composition, and nitrogen concentration was tested, obtaining a maximum PHB concentration of 0.69 g/L, with an average CO₂ uptake rate of 1.14 ± 0.41 mmol CO₂ L^-1h^-1 and 65 % efficiency of CO₂ consumption. These findings lay the groundwork for developing carbon mitigation strategies in alcoholic fermentation processes coupled with sustainable biopolymer production.