Bioresource Technology最新文献

Erythromycin, a broad-spectrum antibiotic, is a prototypical polyketide produced via heterologous biosynthesis in Escherichia coli. However, the instability of plasmid‑encoded genes within the erythromycin biosynthetic pathway, coupled with limited intracellular availability of sugar units and propionyl‑CoA, constitutes major bottlenecks that hinder its efficient production in E. coli. In this study, we constructed a de novo erythromycin A producing E. coli strain throughchromosomal integrationand achieved substantial production improvement by enhancing the supply of sugar units for the erythromycin post-modification and propionyl-CoA. To enable precise and efficient transfer of multiple large DNA fragments from different plasmids into the chromosome, we devised achromosomal integrationstrategy employing a reusable target site toolkit, allowing the integration of four gene expression cassettes (total length ∼ 56.2 kb) into the genome of E. coli BAP1, thereby generating the recombinant strain E. coli sZG9. Subsequently, the availability of sugar units was increased by systematically blocking competing metabolic pathways and introducing a Ser45Asn mutation in the negative regulatory site of phosphoglucomutase, which elevated erythromycin A production from 1.06 mg/L to 5.53 mg/L. Finally, a Lys592Asn mutation in the negative regulatory site of propionyl-CoA synthetase further boosted the production to 9.80 mg/L, representing an 8.25-fold increase over the parental strain. This work establishes an effective large-fragment DNA chromosomal integrationapproach and provides a promising chassis strain for future metabolic engineering efforts aimed at enhancing erythromycin A biosynthesis in E. coli.

Microbial protein is a resource-efficient alternative to conventional protein, and gas-fed systems based on methane- and hydrogen-oxidizing bacteria are attractive because they directly convert gaseous C1 substrates into biomass, without reliance on arable land or organic feedstocks. We examined whether co-cultivating these organisms improves carbon retention by enabling in situ reuse of CO₂ released during CH₄ oxidation. After selecting a compatible pair (Methylomonas koyamae and Cupriavidus necator), a continuous airlift reactor was operated in four phases with progressively reduced external CO₂ supply. Biomass in the co-culture reached 2.1 ± 0.5 g L^-1, with protein contents of 50-65% (dry weight). Off-gas CO₂ decreased to near zero, corresponding to a marked increase in carbon-use efficiency from 47% to 91%. Amino acid composition and digestibility, expressed as the Digestible Indispensable Amino Acid Score, remained stable across phases, and sensory evaluation indicated a lighter colour and cleaner aroma for the co-culture biomass. This study demonstrates a continuous methane- and hydrogen-oxidizing bacteria process achieving near-complete CO₂ recycling and high-quality microbial protein production.

Lignin condensation and the recalcitrance of lignocellulose during conventional fractionation limit their valorization. Herein, we develop a tunable ternary deep eutectic solvent (TDES) composed of guanidine hydrochloride, lactic acid, and ethylene glycol for efficient fractionation of moso bamboo. By modulating the EG content, 74.3% delignification was achieved while preserving lignin structure, as confirmed by a β‑O‑4 content of 26.3/100 Ar (61.3% retention). Lignin nanoparticles self‑assembled into uniform lignin nanobottles (LNBs) with size controlled by lignin structure. Moreover, the preserved structural integrity enabled a high bio‑oil yield of 39.7 wt%. 4‑Vinylphenol was identified by Py‑GC/MS as the dominant product. Strong positive correlations were observed between β‑O‑4 content and both LNBs size and bio‑oil yield. Enzymatic saccharification of the treated residue achieved up to 94.4% glucose conversion. This work establishes a clear structure‑property relationship and presents a "structure‑first" strategy for dual‑pathway lignin valorization into nanomaterials and fuels.

Lignin-carbohydrate complex (LCC), natural plant cell wall macromolecules, has garnered increasing attention for multifunctional bioactivities attributed to a unique lignin-polysaccharide hybrid structure. However, conventional separation methods often compromise the structural integrity and biological function of LCC, limiting practical applications. Herein, a novel two-step xylanase-cellulase method was developed to efficiently isolate functional group-enriched LCC (XCE-LCC) with enhanced free radical scavenging and α-glucosidase inhibitory activities. Comparative analyses revealed that the two-step method partially removed cellulose and hemicellulose barriers while preserving the native LCC structure. Notably, XCE-LCC contained increased levels of bioactive functional groups (phenolic-OH: 0.93 mmol/g, -COOH: 0.23 mmol/g, and aliphatic-OH: 4.38 mmol/g) resulting in DPPH radical scavenging (58.7 %) and particularly high α-glucosidase inhibition (87.4 %). These findings demonstrate an effective enzymatic method for functional group-enriched LCC isolation and underscore the potential of LCC as a functional polymer for oxidative stress mitigation and natural α-glucosidase inhibition.