Dietary Lactobacillus sp. mitigates Deltamethrin-induced toxic and immune-suppression impacts in Nile Tilapia (Oreochromis niloticus)

Abstract Both organic and inorganic contaimanants in the aquatic environment seriously affect marine organisms, including fish. In this study we aim to isolate diatry Lactobacillus sp. from both sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) fish and evaluate their probiotic impact and ability to mitigate the toxic impact of the existing insecticide deltamethrin (DLM) residuals in fish farming water resources. Out of the 40 isolated Lactobacillus sp., 22 were gram positive, catalase-negative and non-hemolytic in the γ hemolysis reaction. One out of the above mentioned 22 isolates (denoted as SB8) were antagonistically reacted with Aeromonas hydrophilic ss. hydrophila (ATCC 130 37) and Pseudomonas fluorescens (ATCC13525). The probiotic candidate SB8 was resistant to acidic conditions, grow well in 0.3% bile salt and 0.4% phenol. Morover, an in-vivo study was conducted on Nile tilapia to evaluate the impact of using the SB8 as feed supplement on haematological profile, oxidative stress enzymatic activities, protein content, micronucleus formation, and IL-1 & IL-6 expression. The obtained results indicated that 1) white blood cells (WBC), neutrophils (Neu), lymphocytes (Lum), monocytes and eosinophils (Mon and Eos, 2) malondialdehyde (MDA), superoxide dismutase (SOD), catalase and glutathione peroxidase (MDA, SOD, CAT and GPx, 3) Protein content (total protein, albumin (A), globulin (B) and albumin/globulin (A/G), 4) micronucleus formation, and 5) Interleukin-1 and Interleukin-6 (IL-1 and IL-6 expression in the DLM-exposed/ SB8-supplemented and in the control fish are reasonably similar in comparison with the DLM-exposed fish. In conclusion, the probiotic candidtae SB8 has a potential to mitigate the DLM-induced deleterious oxidative stress impact in Nile tilapia fish.