BACKGROUND: Microencapsulation of probiotic bacteria is an area that has rapidly expanded over the recent years. It is one of the new methods of improving probiotics stability, through which the biological agents are protected with an enclosed coating to release the active agents within the coating at a controlled rate in time and under special conditions.OBJECTIVES: The present study the aims to evaluate the effect of Lactobacillus plantarum microencapsulation with chitosan/alginate microparticles on the oxidative response of Nile tilapia fish (Oreochromis niloticus).METHODS: Herein, 240 pieces of Nile tilapia, with an average weight of 15.56±0.02 g, were randomly divided into four groups as follows: group1 or control with a diet without probiotics, groups 2, 3, and 4 respectively with a diet containing 108 Log CFU/g of unencapsulated Lactobacillus plantarum, a diet containing microencapsulated Lactobacillus plantarum, and with feed containing alginate with chitosan without the presence of bacteria. They were fed for 60 days at the rate of 2 % of body weight twice a day.RESULTS: The activity level of oxidative enzymes, biochemical factors, and liver enzymes of the Nile tilapia fish were investigated. The findings revealed that oxidative enzymes, biochemical factors, and liver enzymes were positively affected in the groups with microencapsulated Lactobacillus plantarum (P<0.05). The three enzymes of alanine transaminase, aspartate transaminase, and alkaline phosphatase were higher in the micro-encapsulated probiotic group compared to the two groups of probiotics and alginate with chitosan without the presence of bacteria, and all the three groups performed better compared to the control (P<0.05).CONCLUSIONS: Microencapsulation of probiotics maximizes the efficiency of probiotics in reducing oxidative stress.

BACKGROUND: Probiotics have more functional effects and less survival  under hard acidic-bile circumstances of digestive system, and foodstuff products situation has persuaded investigators to find techniques to resolve this problem. Microencapsulation as a useful method has a perceptible effect in this regard. Objectives: The aim of this study was to assess the protective role of double coated beads of calcium alginate-chitosan-eudragit S100 achieved from microencapsulation of Lactobacillus acidophilus as a predominant flora of human and animals gut. Methods: Following activation of starter culture of L.acidophilus in MRS-broth medium,  centrifuge (at aspeed of 5000 rpm for 10 minutes) was used to purify bacteria. Extrusion technique was used for Microencapsulation of probiotic bacterium. The survey of beads solidity was carried out for 12 hours and the study of survival of microencapsulated bacteria was done for 120 minutes inside hydrochloric acid, phosphate buffer and digestive powder solution.  MRS-Salicin-agar and pour plate method and incubation at 37oC for 48 h was done for cultivation. Data were analyzed by means of an independent t-test. Results: Shape and size of beads were shown by optical microscope. The consequences demonstrated that survivability of microencapsulated bacteria in the mentioned conditions, in both situation with and without mechanical tensions, is significantly more than free bacteria (p<0/05). Conclusions: Microencapsulation with calcium alginate- chitosan-eudragit S100 plays a significant role  in increasing the rate of L. acidophilus viability.