Chitobiose is a high-value, chitin-derived disaccharide with promising potential for agricultural application. Unfortunately, current production methods rely on hazardous chemical and costly enzymatic processing and the resulting high cost prohibits its commercial application. In this work, we report a simple, scalable fermentation platform, based on a Streptomyces venezuelae ΔdasBC transporter mutant that converts raw chitin directly into chitobiose. By tuning production parameters to maximize titer, the process yielded an estimated 450 mg/L chitobiose without chitin pretreatment or enzymatic steps. Liquid chromatography/mass spectrometry showed the product to be highly enriched for chitobiose with the absence of detectable longer N-acetylglucosamine oligomers. To explore the potential agricultural application, we tested the crude spent medium as a biostimulant. As a soil additive, it increased Arabidopsis thaliana rosette size by up to 22
NADPH competition by non-erythrose-reductase oxidoreductases limits erythritol yields in Yarrowia lipolytica, yet the specific contributors remain poorly defined. This study characterised two candidate genes, YALI0_F02013g (putative pyridoxine 4-dehydrogenase) and YALI0_A19910g (putative glycerol 2-dehydrogenase), using time-resolved transcriptomics, molecular docking and metabolic modelling. RNA-seq analysis across 96 h of fermentation revealed distinct temporal profiles: YALI0_F02013g was progressively induced 3.4-fold (peak 5040 FPKM at 72 h), while YALI0_A19910g was repressed 920-fold by 96 h (Table 2). Expression trends were validated by qRT-PCR (Pearson r > 0.94; Table 3). YALI0_A19910g expression correlated strongly negatively with erythritol titre (Pearson r = − 0.858), whereas YALI0_F02013g showed a weak positive correlation. Molecular docking predicted high NADPH binding affinities for both enzymes (− 9.8 and − 8.6 kcal mol⁻1, respectively; Fig. 2) and identified conserved catalytic triads. An integrated prioritisation model ranked YALI0_F02013g as the higher-priority target (5.6/10 vs 5.0/10; Table 7). In silico flux estimates suggest that repressing YALI0_F02013g could conserve approximately 67
Clostridium aceticum, a model acetogen utilizing the Wood–Ljungdahl pathway (WLP), offers a promising microbial platform for converting CO2-rich syngas into value-added biofuels. In this study, we systematically investigated the effects of varying CO2 concentrations on fermentation kinetics and global transcriptional responses of C. aceticum. Acetate production increased steadily with higher CO2 levels, reaching 12.3 g/L at 45
Abstract Background The pattern of xylan backbone substitution by 4- O -methylglucuronic acid (mGlcA) and O -acetyl groups generated during biosynthesis in the Golgi apparatus plays a key role in molecular interactions between secondary cell wall polymers in hardwoods, thus regulating biorefinery properties of woody biomass. This study aims at comparing the effects of two different approaches to reduce xylan glucuronidation, targeting either xylan biosynthesis by RNAi suppression of GLUCURONIC SUBSTITUTION OF XYLAN1 genes (denoted Gux1RNAi) or by xylan post-synthetic modification in the secondary cell wall by apoplastic wood-specific expression of a fungal α-glucuronidase from family GH67 (denoted WP:GH67) in hybrid aspen (Populus tremula L. x tremuloides Michx.). The effects of reducing xylan glucuronidation by these two approaches on xylan acetylation and solubility, and recalcitrance of wood to enzymatic hydrolysis were compared. Results Both approaches reduced mGlcA/xylose (Xyl) ratio by approx. 30% without altering Xyl content in alkali extracts, while xylan acetyl content in subcritical water extracts was increased only in Gux1RNAi lines. The Gux1RNAi lines showed reduced glucuronidation in the major xylan domain containing evenly-spaced mGlcA, whereas the WP:GH67 lines were affected in both odd and even glucuronidation patterns. Interestingly, the arrays containing mGlcA every second xylosyl unit were not affected by any modification, whereas an increase in xylo-oligosaccharides containing O -2,3 diacetylated Xyl was found in Gux1RNAi lines only. Neither modification consistently affected glucose or Xyl yields in saccharification without or with acid pretreatment, whereas xylan extractability in subcritical water was increased in Gux1RNAi, but not in WP:GH67 lines. Conclusion Our study supports the hypothesis that acetylation competes with glucuronidation by GUX1 during biosynthesis, and increased acetylation caused by GUX1 suppression rather than reduced xylan glucuronidation per se improves xylan extractability. The 30% reduction in glucuronidation did not affect enzymatic saccharification, supporting the concept that cell wall structure and recalcitrance in transgenic lines are maintained by xylan domains which were not affected by either transgenic modification.
A green strategy for enhancing laccase production by Funalia trogii in submerged fermentation using p-coumaric acid (pCA) as an inducer was investigated. Supplementation with 0.026
