Variation in average well color development (AWCD) over time in Biolog ECO-microplates.

<p>Soil samples were tested from rhizosphere of maize treated with different mulching and fertilizer treatments. The values are the means of three replicates (means±SD).</p

Relative substrate utilization for six substrate categories in each treatment.

<p>Soil samples were tested from rhizosphere of maize treated with different mulching and fertilizer treatments. The values are the means of three replicates, and different letters above the bars indicate significant differences at the P < 0.05 level.</p

N accumulation during the pre- and post-silking period and of grain at maturity in different mulching and fertilizer treatments.

<p>The values are the means of three replicates, and different letters above the bars indicate significant differences at the P < 0.05 level.</p

Microbial Functional Diversity, Biomass and Activity as Affected by Soil Surface Mulching in a Semiarid Farmland - Fig 2

<p><b>The microbial biomass C and microbial biomass N (a) and dehydrogenase activity and urease activity (b) in each treatment. Soil samples were tested from rhizosphere of maize treated with different mulching and fertilizer treatments.</b> The values are the means of three replicates, and different letters above the bars indicate significant differences at the P < 0.05 level. NMC, no mulching with inorganic N fertilizers; GMC, gravel mulching with inorganic N fertilizers; FMC, plastic-film mulching with inorganic N fertilizers; FMO, plastic-film mulching with chemical N fertilizers and organic manure addition.</p

Principal component analysis of CLPP results from maize rhizosphere soil treated with different mulching and fertilizer treatments.

<p>Soil samples were tested from rhizosphere of maize treated with different mulching and fertilizer treatments.</p

Loadings of 31 carbon substrates on PC1 and PC2 in the principal components analysis of the CLPP results.

<p>Carbon source: A1: Water, A2: β-methyl-D-glucoside, A3: D-galactonic acid γ-lactone, A4: L-arginine, B1: Pyruvic acid methyl ester, B2: D-xylose, B3: D-galacturonic acid, B4: L-asparagine, C1: Tween 40, C2: I-erythritol, C3: 2-hydroxybenzoic acid, C4: L-phenylalanine, D1: Tween 80, D2: D-mannitol, D3: 4-hydroxybenzoic acid, D4: L-serine, E1: α-cyclodextrin, E2: N-acetyl-D-glucosamine, E3: γ-hydroxybutyric acid, E4: L-threonine, F1: Glycogen, F2: D-glucosaminic acid, F3: Itaconic acid, F4: Glycyl-L-glutamic acid, G1: D-cellobiose, G2: Glucose-1-phosphate, G3: α-ketobutyric acid, G4: Phenylethylamine, H1:α-D-lactose, H2: D,L-α-glycerol phosphate, H3: D-malic acid, H4:Putrescine.</p

Investigate the Metabolic Reprogramming of <i>Saccharomyces cerevisiae</i> for Enhanced Resistance to Mixed Fermentation Inhibitors via ¹³C Metabolic Flux Analysis

<div><p>The fermentation inhibitors from the pretreatment of lignocellulosic materials, e.g., acetic acid and furfural, are notorious due to their negative effects on the cell growth and chemical production. However, the metabolic reprogramming of the cells under these stress conditions, especially metabolic response for resistance to mixed inhibitors, has not been systematically investigated and remains mysterious. Therefore, in this study, ¹³C metabolic flux analysis (¹³C-MFA), a powerful tool to elucidate the intracellular carbon flux distributions, has been applied to two <i>Saccharomyces cerevisiae</i> strains with different tolerances to the inhibitors under acetic acid, furfural, and mixed (i.e., acetic acid and furfural) stress conditions to unravel the key metabolic responses. By analyzing the intracellular carbon fluxes as well as the energy and cofactor utilization under different conditions, we uncovered varied metabolic responses to different inhibitors. Under acetate stress, ATP and NADH production was slightly impaired, while NADPH tended towards overproduction. Under furfural stress, ATP and cofactors (including both NADH and NADPH) tended to be overproduced. However, under dual-stress condition, production of ATP and cofactors was severely impaired due to synergistic stress caused by the simultaneous addition of two fermentation inhibitors. Such phenomenon indicated the pivotal role of the energy and cofactor utilization in resisting the mixed inhibitors of acetic acid and furfural. Based on the discoveries, valuable insights are provided to improve the tolerance of <i>S</i>. <i>cerevisiae</i> strain and further enhance lignocellulosic fermentation.</p></div

Fold changes of key fluxes between the S-C1 and YC1 strain under different stress conditions.

<p>Abbreviation: GLC, glucose; G6P, glucose-6-phosphate; F6P, fructose-6-phosphate; PEP, phosphoenolpyruvate; PYRCYT, pyruvate in cytosol; P5P, ribulose 5-phosphate; ICIT, isocitrate; AKG, α-ketoglutarate; ETH, ethanol; ETHOUT, extracellular ethanol; GLYC, glycerol; GLYCOUT, extracellular glycerol.</p

Production and consumption of cofactor and energy.

<p>The consumption (blue bar), production (red bar), and net production (black dots) of ATP, NADH, and NADPH are shown for different stress conditions. The error bars present the standard deviations, which can be too small to be seen.</p

Metabolic flux distribution of the S-C1 strain and YC1 strain under different stress conditions.

<p>The values outside the bracket are relative flux values normalized to glucose uptake rates as 100. The values inside the bracket are real flux values in mmol/g/h. Abbreviations used are: G3P, glyceraldehyde 3-phosphate; TCA cycle, tricarboxylic acid cycle. The line widths are linearly correlated with the normalized flux values (glucose uptake rate as 100). The dashed line indicates the flux is zero.</p