Effects of humic acids on the recovery of different bacterial strains in an in vitro chicken digestive model

• Published in: Research in veterinary science 2022-07, Vol.145, p.21-28
• Main Authors: Maguey-González, Jesús Adonai, Gómez-Rosales, Sergio, Angeles, Maria de Lourdes, López-Hernández, Luis Humberto, Rodríguez-Hernández, Elba, Solís-Cruz, Bruno, Hernández-Patlán, Daniel, Merino-Gúzman, Rubén, Téllez-Isaías, Guillermo
• Format: Article
• Language: English
• Subjects: Animals; Antibiotics; Antimicrobial agents; Bacillus subtilis; Bacteria; Bacterial strains; Chickens; Chickens - microbiology; Coliforms; Digestive model, chickens; Digestive system; E coli; Escherichia coli; Gastrointestinal tract; Humic acids; Humic Substances; In vitro; In vivo methods and tests; Intestinal microflora; Intestine; Microbiota; pH conditions; Poultry; Poultry Diseases - microbiology; Probiotics; Recovery; Salmonella; Strains (organisms); Variance analysis; Veterinary medicine
• ISSN: 0034-5288; 1532-2661
• DOI: 10.1016/j.rvsc.2022.01.004

Humic acids (HA) have been evaluated as growth promoters in poultry, but their effects on the gut microbiota remains controversial using in vitro and in vivo models. The objective of this study was to determine the effect of HA extracted from a wormcompost on the recovery of bacteria: Salmonella Enteritidis (S. Enteritidis), Escherichia coli (E. coli), Clostridium perfringens (C. perfringens), Bacillus subtilis (B. subtilis) and Lactobacillus salivarius (L. salivarius) using an in vitro chicken digestive system. Independent in vitro trials were run for each bacteria using six treatments: 1) Negative control with no bacteria added (Control-), 2) Positive control added with bacteria (Control+), 3) 0.1% HA + bacteria, 4) 0.2% HA + bacteria, 5) 0.5% HA + bacteria and 6) 1% HA + bacteria. Data was subjected to analysis of variance and linear regression. In the crop, S. Enteritidis was lower, C. perfringes and B. subtilis were not affected by HA, while E. coli and L. salivarius were higher at 0.5 and 1% HA inclusion (P ≤ 0.0001). In the proventriculus, S. Enteritidis, E. coli and B. subtilis were higher at 0.5 and 1% HA inclusion (P ≤ 0.0001); C. perfringens and L. salivarius were not affected by HA. In intestine, significant increases of all bacteria strains were observed (P ≤ 0.0001). In conclusion, the results suggests that HA can be used as prebiotic, but their mechanisms of action to stimulate the growth of gut bacteria remains to be elucidated. •In the crop, HA increased the counts of E. coli and L. salivarius.•In the proventriculus, HA enhanced the counts of S. Enteritidis, E. coli and B. subtilis.•In the intestine, HA stimulated the growth of five strains of bacteria.•HA can be used as prebiotic in poultry.