Dietary Agaricus blazei Spent Substrate Improves Disease Resistance of Nile Tilapia (Oreochromis niloticus) against Streptococcus agalactiae In Vivo

Abstract

This study evaluated the effects of the feeding of spent mushroom substrate from Agaricus blazei on Nile tilapia (Oreochromis niloticus). The safety of 0–1000 μg/mL A. blazei spent substrate water extract (ABSSE) was demonstrated in the primary hepatic and splenic macrophages and the THK cell line (a cell line with characteristics of melanomacrophages) using a cytotoxicity assay. Here, 10 μg/mL of crude ABSSE promoted the phagocytic activity of macrophages and THK cells. Stimulating ABSSE-primed THK cells with lipopolysaccharides or peptidoglycan resulted in higher expression levels of four cytokine genes (e.g., interleukinz (IL)-1β, IL-12b, IL-8 and tumor necrosis factor α (TNFα)) and one cytokine gene (TNFα), respectively. An in vitro bacterial growth inhibition assay demonstrated that ABSSE could inhibit the growth of Streptococcus agalactiae. In the first feeding trial, Nile tilapia were fed with experimental feed containing 0, 1, or 5% of A. blazei spent substrate (ABSS) for seven and fourteen days followed by bacterial challenge assay. The best result was obtained when Nile tilapia were continuously fed for seven days on a diet containing 1% ABSS, with the survival rate being higher than in groups with 0% and 5% ABSS after challenge with S. agalactiae. In the second trial, fish were fed diets supplemented with 0% or 1% ABSS for seven days, and then all the groups were given the control feed for several days prior to bacterial challenge in order to investigate the duration of the protective effect provided by ABSS. The results showed that the protective effects were sustained at day 7 after the feed was switched. Overall, spent mushroom substrate from A. blazei is a cost-effective feed additive for Nile tilapia that protects fish from S. agalactiae infection.

Acid external and internal environment exchange the Oreochromis niloticus tissue immune gene expression compared to the mouse macrophage polarization model

“…TNF-α ( 23 ): forward primer: GAA CAC TGG CGA CAA AAC AGA;reverse primer: TTG AGT CGC TGC CTT CTA GA…”

“…IL-12β ( 23 ): forward primer: CAA CAG TGA CAA TCA AAT AAT TAA TAT;reverse primer: CGT TAT GTT TGT TCA CTG TGC A…”

“…IL-8 ( 23 ): forward primer: TCG CCA CCT GTG AAG GCA T;reverse primer: TCC TTT TCA GTG TGG CAA TGA T…”

“…β-actin ( 23 ): forward primer: TCC TTC CTT GGT ATG GAA TCC;reverse primer: GTG GGG CAA TGA TCT TGA TC…”

Fish Responses to Alternative Feeding Ingredients under Abiotic Chronic Stress

“…P.T. Lee, Wu, Tseng, Lu, and Lee described efforts to recycle and reuse waste mushroom compost, taking advantage of its immunomodulatory compounds, highlighting that waste mushroom substrate from A. blazei cultivation is a cost-effective feed additive for Oreochromis niloticus that protects fish from S. agalactiae infection [ 112 ].…”