Effects of microencapsulation of Lactobacillus rhamnosus by internal emulsification with alginate / chitosan on some of the immunological parameters in rainbow trout (Oncorhynchus mykiss)

The application of probiotics in aquaculture has been increased in recent years due to the many benefits for fish health. The most important factors in reducing the viability of probiotics during passing through the digestive system are low pH in stomach and proteases and bile salts. Encapsulating of probiotics within biodegradable nanoparticles has been found to increase their viability and efficiency in fish gut. In the current study, the effects of microencapsulation of Lactobacillus rhamnosus by internal emulsification with alginate / chitosan on some of the immunological parameters in rainbow trout (Oncorhynchus mykiss) were evaluated. An experiment was designed with four treatments each with three replicates. 480 juvenile rainbow trout average (±SD) initial weight of 25.53±.82 g was assigned to fifteen experimental tanks. Fish in T1 received Lactobacillus rhamnosus encapsulated by internal emulsification with alginate / chitosan, T2 were fed with alginate/chitosan enriched free probiotic diet, T3 received bacteria without any encapsulation and T4 received basic diet as a control group. All treatments were fed with experimental diets for 60 days. Fish were sampled on days 30 and 60 and some of the immunological parameters consist of Lysozime, Complement, Total protein, Albumin, Globulin and NBT were measured. Results showed that lysozyme in treatment of encapsulated by internal emulsification significantly was higher than other groups at day 30 and 60 of experiment (p<0.05). Also, a significant increase was served in the total protein and globulin in T1 and T2 at day 30 compared to the other groups and at day 60 compared to the control group (p<0.05). Generally, it can be concluded that the microencapsulation of Lactobacillus rhamnosus by internal emulsification with alginate / chitosan has significant effects on some of the immunological parameters in rainbow trout and improved the immune responses in this fish. Results showed that lysozyme in treatment of encapsulated by internal emulsification significantly was higher than other groups at day 30 and 60 of experiment (p<0.05). Also a significant increase was bserved in the total protein and globulin in T1 and T2 at day 30 compared to the other groups and at day 60 compared to the control group (p<0.05).
Generally, it can be concluded that the microencapsulation of Lactobacillus rhamnosus by internal emulsification with alginate / chitosan has significant effects on some of the immunological parameters in rainbow trout (Oncorhynchus mykiss) and improved the immune responses in this fish.