Table 2.
Effect of chitin derivatives on the gut microbiota different species.
| Type of Study | Insect/Crustacean, Dosage and Time of Exposure | Characterization | Significant Changes in Gut Microbiota | Significant Changes in Metabolites and Metabolic Effects | Reference |
|---|---|---|---|---|---|
| In vitro determination of bacteria grown in tryptone soy broth comparing E. coli vs. Lactobacillus rhamnosus | Chitin was tested at concentrations of 5 and 1 g/L, whereas COS was tested at concentrations of 5, 1, and 0.5 g/L | COS powder ≤ 1.5 kDa and degree of deacetylation ≥ 90%. Chitin was prepared at a concentration in the range 1–5 g/L. COS was prepared in the range 0.5–5 g/L | COS reduced the growth of E. coli, whereas chitin totally inhibited E. coli growth. COS stimulated the growth of L. rhamnosus, whereas chitin inhibited its growth | Not provided | [2] |
| In vitro determination of minimal inhibitory concentrations against E. coli and Staphylococcus aureus in broth, milk and apple juice | Minimal inhibitory concentrations were tested in the range 0–0.6% w/v. 0.5% w/v chitosan and COS in milk and apple juice | Chitosan with average molecular weights of 628, 591 and 107 kDa and a degree of deacetylation in the range 80–85%. COS with molecular weight of < 5 and < 3 kDa and a degree of deacetylation in the range 80–85% | COS showed higher antibacterial activity than chitosan against E. coli, whereas chitosan showed higher antibacterial activity than COS in S. aureus. The use of chitosan in foods will be limited to foods that possess a low protein content | Not provided | [23] |
| In vivo trial using 24 C57BL/6J mice | 1 mg/mL in water, about 200 mg/kg/day for 3 months | COS < 1 kDa with deacetylation degree of 88% | Significant decrease in Firmicutes phylum and increase in Bacteroidetes phylum in dp/dp mice. At genus level, markedly reduced Lachnospiraceae NK4A136 group, Alistipes, Helicobacter, Ruminococcus and Odoribacter, while Lachnospiraceae UCG 001 and Akkermansia increased | Lower fasting glucose, better insulin tolerance. Reduced weight of white fat tissue. Significant decrease in mRNA levels of inflammation markers such as TNF-α, MCP-1 and macrophage biomarker CD11c | [46] |
| In vivo trial using adult zebrafish (Danio rerio) | 2% of zebrafish diet for 60 days | Chitosan–silver nanocomposites | Increase of Bacteroidetes, Fusobacteria and unassigned other phylum, whereas Proteobacteria decreased | Increase in goblet cell density and in villi height. Genes of IL-6 and 12 showed significantly higher regulation, whereas mucin-encoding genes, such as Muc 5.1 and Muc 2.1 showed upregulation in treated fish | [48] |
| In vivo trial using 144 piglets (Duroc × landrace × Yorkshire) | 100, 200 or 400 mg/kg in feed for 28 days | Chitosan nanoparticles with a particle size of about 50 nm, average molecular weight of 220 kDa and degree of deacetylation of 95% | Increase in GM diversity and Bacteroidetes, Prevotellaceae and Ruminococcus while Firmicutes and Clostridiaceae family decreased | Improvement in growth performance. Improvement in immunoglobulin IgA, IgG, C3 and C4. Decrease in plasma cortisol, PEG2, IL-6 and IL-1ß | [49] |
| In vitro trial investigating effects on growth of 100 Bifidobacterium and in vivo trial in 24 Groningen rats | In vitro trial at 0.5% GC w/v concentration. Rat diet was supplemented with 10% GC (w/w) | GC was obtained from A. niger by a tyndallization procedure | Increase of Bifidobacterium adolescentis and B. longum. Decrease in Firmicutes to Bacteroidetes ratio and improved colonization efficiency of B. breve | Decrease in body weight gain with respect to controls | [56] |
| In vivo trial using 20 C57BL/6J mice | 1 mg/mL chitin oligosaccharide (NACOS) in drinking water (about 200 mg/kg/day) for 5 months in a high-fat diet | NACOS with a polymerization degree 2–6 | Increase of Lactobacillus, Bifidobacterium, Akkermansia and Bacteroides whereas Desulfovibrio and Firmicutes to Bacteroidetes ratio decreased | Decrease in mRNA of cytokines, including TNF-α, IL-6, MCP-1 and LPS in serum. Improved bacterial motility, oxidative stress, energy metabolism and inflammation process | [57] |
| In vivo using 130 subjects free of diabetes mellitus | Participants were randomly assigned to receive chitin–glucan (GC) (4.5 g/day; n = 33), GC (1.5 g/day; n = 32), GC (1.5 g/day) plus olive oil extract (135 mg/day; n = 30) or matching placebo (n = 35) for 6 weeks | GC derived from Aspergillus niger mycelium | Not provided | Administration of 4.5 g/day GC for 6 weeks significantly reduced oxidized low-density lipoprotein. At the end of the study, GC was associated with lower LDL-C levels, although this difference was statistically significant only for the GC 1.5 g/day group | [73] |
| In vitro trial using trypticase phyton yeast inoculated with different Bifidobacterium strains | 0.025%, 0.1% and 0.5% low-molar-mass chitosan, chitosan succinate; chitosan glutamate and 0.1% and 0.5% COS in anerobic trypticase phyton yeast medium | Chitosan molecular weight 75 kDa; degree of deacetylation 83%, prepared by enzyme hydrolysis to obtain different fractions | Both chitosan and all derivatives inhibited Bifidobacterium growth | Not provided | [74] |
| In vitro fermentation using fresh feces of C57BL/6J mice | 1 g/L of COS in drinking water, about 200 mg/kg/day for 5 months | COS with deacetylation degree over 95% and average molecular weight < 1 kDa | Increase of Bacteroidetes and Verrucomicrobia phyla whereas Proteobacteria and Firmicutes phyla decreased | Increase in colonic H2, acetate and butyrate | [75] |
| In vivo using 24 C57BL/6J mice | GC (10% w/w). Food intake was recorded, taking into account spillage, twice a week for 4 weeks | GC was derived from the cell walls of the mycelium of A. niger | GC supplementation increased the quantities of Bacteroides–Prevotella spp., whereas the Clostridium coccoides–Eubacterium rectale cluster group and Roseburia spp. were completely restored after GC treatment. Bifidobacteria in the high-fat GC-fed mice were higher than in the high fat-fed mice or control mice | GC decreased body weight gain by about 28% as compared to high-fat diet. This effect was accompanied by lower fat mass development. Consumption of GC showed potential beneficial effects with respect to the development of obesity and associated metabolic disorders such as diabetes and hepatic steatosis | [76] |
| In vivo trial using 40 male Sprague-Dawley rats | COS (0.3 g/day), resistant starch (1.2 g/day) and COS combined with resistant starch (1.5 g/day) slurried with drinking water for 6 weeks | COS with an average molecular weight about 5 kDa and a deacetylation degree of 83% | COS increased Bacteroidetes and decreased Firmicutes. COS combined with resistant starch Blautia and Allobacterium | COS combined with resistant starch decreased protein-fermentation markers such as H2S2, ammonia, phenols and indole. It also increased excretion of bile acids in feces, the thickness of the mucosal layer and SCFA production | [77] |
| In vivo using 12 Wistar rats | Control group received pellets with commercial diet ST-1. Treated group pellets had chitosan or COS added at a final concentration of 10 g/kg in feed mixture) for 4 weeks | COS obtained by cellulase hydrolysis of chitosan from A. niger | Increase of total bacterial population in the group of Bacteroides–Prevotella and the Clostridium leptum subgroup was found in response to chitosan intake. Chitosan intake also reduced Enterobacteriaceae and Lactobacillus group bacteria. COS intake influenced Bacteroides–Prevotella group and Enterobacteriaceae bacteria in the same way | Not provided | [78] |
| In vivo trial using 40 pigs | Basal diet plus 1000 µg/kg chitosan for 63 days | Chitosan obtained from prawn (Nephrops norvegicus) | Chitosan supplementation decreased Firmicutes in the colon and decreased Lactobacillus spp. in both the cecum and colon, while Bifidobacterium increased in the cecum | Reduced feed intake and body weight in pigs | [79] |
| In vivo trial using 24 Syrian golden hamsters with dyslipidemia previously induced with high-fat diet | 150 mg/kg/day for 8 weeks | Chitosan with degree of diacylation higher than 85% combined to Ganoderma polysaccharides at 1:1 ratio | Increase of Ruminococcus, Oscillibacter, Bifidobacterium, Prevotella, Alloprevotella and Paraprevotella | Triglycerides, total cholesterol, low-density lipoprotein cholesterol and aspartate aminotransferase were reduced in the serum of hamsters fed chitosan-added diet | [80] |
| In vivo trial using 60 pigs | Basal diet with 50 g/Tm added for 28 days | Low molecular weight chitosan | Increase in Bacteroidetes, decrease in Firmicutes. Increase in Prevotella but decrease in Lactobacillus | Chitosan supplementation improved metabolic pathways including energy metabolism, metabolism of terpenoids and polyketides, digestive systems, cell growth and death, glycan biosynthesis and metabolism as well as metabolism of cofactors and vitamins | [81] |
GC: Chitin-glucan; IL-1: Interleukin 1; IL-6: Interleukin 6; IgA: Inmunoglobulin A; IgG: Inmunoglobulin G; LDL-C: low-density lipoprotein cholesterol; LPS: lipopolysaccharide; MCP-1: monocyte chemoattractant protein-1; NACOS: chitin oligosaccharide; mRNA: messenger RNA; TNF-α: tumor necrosis factor alpha; SCFA: Short chain fatty acids; PEG2: Prostaglandin E-2.