Figures (4)  Tables (4)

    • Figure 1. 

      Schematic workflow for constructing the engineered strain and for microbial lipid production. (a) Schematic diagram of the genetic engineering and fermentation process for microbial lipid production. (b) Proposed pathway for fatty acid biosynthesis from the glucose in PD630. Abbreviations: ED, Entner-Doudoroff pathway; G-6-P, glucose-6-phosphate; GAP, glyceraldehyde-3-phosphate; ACP, acyl carrier protein. (c) Growth curves of wild-type and engineered PD630 strains. (d) Biomass production of wild-type and engineered PD630 strains. (e) Fatty acid composition (relative abundance, %) and absolute content of wild-type and engineered PD630 strains. (f) Total lipid content of wild-type and engineered PD630 strains. Data are presented as the mean ± sem (n = 3). The three biological replicates represent independent PD630 bacterial samples used for molecular analysis.

    • Figure 2. 

      Optimization of finishing pig feed formulations using PSO and ACO algorithms. (a) Comparison of convergence processes between PSO and ACO algorithms. (b) Variation in raw material proportions during the optimization process. (c) Feed composition in PSO and ACO algorithms. (d) Nutrient profiles of PSO and ACO algorithms. (e) Energy values (DE, ME, NE) of the ACO algorithm. (f) Lysine-to-ME ratio in PSO and ACO algorithms. (g) Comparison of feed cost among baseline, PSO, and ACO algorithms.

    • Figure 3. 

      Effects of lipids from engineered PD630 on muscle fiber type and morphology in the longissimus dorsi muscle of finishing pigs. (a) Representative images of muscle paraffin sections; scale bars, 150 μm. (b) Quantification of muscle fiber cross-sectional area. (c) Triglyceride content in the longissimus dorsi muscle. (d) Protein synthesis genes. (e) Protein degradation genes. (f) Immunofluorescence staining of fast (green) and slow (red) myofibers; scale bars, 200 μm. (g) Myofiber-type markers. Data are presented as the mean ± sem (n = 3). Three samples were randomly selected from the six slaughtered pigs in each group for subsequent molecular analysis.

    • Figure 4. 

      Effects of lipids from engineered PD630 on intestinal morphology in finishing pigs. (a) Duodenal intestine H&E staining; scale bars, 200 μm. (b) Crypt depth (μm) (n = 3). (c) Villus height (μm) (n = 3). (d) Relative mRNA expression of intestinal barrier-related genes in the duodenum (n = 3). (e) Alpha diversity index: Chao1 (n = 4). (f) Alpha diversity index: ACE (n = 4). (g) Alpha diversity index: Shannon (n = 4). (h) Alpha diversity index: Simpson (n = 4). (i) Beta diversity analysis at the phylum level (n = 4). (j) Beta diversity analysis at the genus level (n = 4). (k) Relative abundances of dominant bacterial phyla (n = 4). (l) Relative abundances of dominant bacterial genera. (m) Relative abundances of Firmicutes and Bacteroidota at the phylum level (n = 4). (n) Firmicutes/Bacteroidota (F/B) ratio (n = 4). (o) Relative abundances of representative bacterial genera (Streptococcus, Lactobacillus, and Treponema) (n = 4). (p) LEfSe analysis of differentially enriched taxa. Data were presented as the mean ± sem. Three or four samples were randomly selected from the six slaughtered pigs in each group for subsequent molecular analysis.

    • Items Con PD630 p-Value
      ADG, kg/d 0.56 ± 0.04 0.6 ± 0.07 0.397
      ADFI, kg/d 3.19 ± 0.07 3.22 ± 0.05 0.892
      FCR 5.70 ± 0.14 5.37 ± 0.09 0.992
      ADG = average daily gain; ADFI = average daily feed intake; FCR = feed conversion rate. Data are presented as the mean ± sem (n = 6 pigs per group, randomly selected for slaughter).

      Table 1. 

      Effects of lipids from engineered PD630 (as a substitute for dietary lipids) on the growth performance of finishing pigs.

    • Items Con PD630 p-Value
      Carcass weight, kg 82.67 ± 6.47 86.45 ± 2.10 0.299
      Backfat thickness, cm 1.93 ± 0.22 2.70 ± 0.27 0.001
      Dressing percentage, % 68.00 ± 1.26 72.00 ± 0.41 0.037
      Data are presented as the mean ± sem (n = 6 pigs per group, randomly selected for slaughter).

      Table 2. 

      Effects of lipids from engineered PD630 (as a substitute for dietary lipids) on the carcass characteristics of finishing pigs.

    • Item Con PD630 p-Value
      C6:0 0.01 ± 0.00 0.02 ± 0.01 0.589
      C8:0 0.02 ± 0.00 0.02 ± 0.01 0.792
      C10:0 0.15 ± 0.01 0.16 ± 0.0 0.789
      C12:0 0.13 ± 0.01 0.13 ± 0.01 0.984
      C13:0 0.03 ± 0.002 0.02 ± 0.001 0.578
      C14:0 1.50 ± 0.09 1.50 ± 0.21 0.886
      C14:1 1.25 ± 0.07 1.22 ± 0.14 0.866
      C15:0 1.26 ± 0.35 1.27 ± 0.6 0.975
      C16:0 13.10 ± 0.55 12.80 ± 1.37 0.751
      C16:1 3.04 ± 0.20 2.74 ± 0.54 0.276
      C17:0 0.72 ± 0.12 0.82 ± 0.23 0.433
      C18:0 12.59 ± 1.45 13.88 ± 2.84 0.385
      C18:1n-9 41.47 ± 1.64 43.10 ± 7.20 0.844
      C18:2n-6 19.72 ± 1.72 17.50 ± 1.02 0.610
      C18:3n-3 0.46 ± 0.03 0.47 ± 0.02 0.877
      C18:3n-6 0.13 ± 0.01 0.17 ± 0.01 0.544
      C20:0 0.65 ± 0.07 0.76 ± 0.20 0.260
      C20:3n-3 1.78 ± 0.62 1.76 ± 0.21 0.876
      C20:3n-6 0.67 ± 0.08 0.67 ± 0.03 0.976
      C20:5n-3 (EPA) 0.31 ± 0.05 0.39 ± 0.03 0.387
      C22:0 1.07 ± 0.04 1.09 ± 0.21 0.958
      C22:1n-9 3.26 ± 0.30 2.57 ± 0.30 0.245
      Data are presented as the mean ± sem (n = 3). Three samples were randomly selected from the six slaughtered pigs in each group for subsequent molecular analysis.

      Table 3. 

      Effects of lipids from engineered PD630 (as a substitute for dietary fat) on the fatty acid composition in the muscle of finishing pigs (% of total fatty acids).

    • Item Con PD630 p-Value
      Aspartic 2.00 ± 0.03 2.15 ± 0.02 0.032
      Threonine 1.01 ± 0.02 1.18 ± 0.01 0.017
      Serine 0.82 ± 0.01 0.88 ± 0.01 0.026
      Glutamine 3.06 ± 0.06 2.94 ± 0.04 0.128
      Proline 1.67 ± 0.03 2.25 ± 0.02 0.001
      Glycine 0.87 ± 0.02 0.93 ± 0.01 0.038
      Alanine 1.15 ± 0.02 1.14 ± 0.01 0.666
      Cysteine 0.11 ± 0.01 0.12 ± 0.00 0.045
      Valine 1.05 ± 0.02 1.01 ± 0.01 0.065
      Methionine 0.58 ± 0.00 0.62 ± 0.01 0.008
      Isoleucine 0.99 ± 0.01 0.98 ± 0.01 0.570
      Leucine 1.76 ± 0.03 1.89 ± 0.01 0.009
      Tyrosine 0.77 ± 0.01 0.75 ± 0.01 0.082
      Phenylalanine 1.06 ± 0.02 1.14 ± 0.01 0.011
      Lysine 1.88 ± 0.0 2.01 ± 0.02 0.007
      Histidine 0.98 ± 0.02 0.95 ± 0.00 0.327
      Arginine 1.34 ± 0.01 1.30 ± 0.03 0.102
      TAA 21.21 ± 0.35 22.83 ± 0.18 0.008
      EAA 10.6 ± 0.14 11.17 ± 0.04 0.030
      EAA = essential amino acids; TAA = total amino acids. Data are presented as the mean ± sem (n = 3). Three samples were randomly selected from the six slaughtered pigs in each group for subsequent molecular analysis.

      Table 4. 

      Effects of lipids from engineered PD630 (as a substitute for dietary fat) on the amino acid composition in the muscle of finishing pigs (% of meat weight).