Herbal hydrogels based encapsulated Enterococcus faecium ABRIINW.N7 improves the resistance of red hybrid tilapia against Streptococcus iniae.

AIMS The Streptococcal disease has been associated with serious mortality and significant global economic loss in the tilapia farming industry. The overall goal of this work was to test herbal hydrogels based on encapsulated Enterococcus faecium ABRIINW.N7 for potential probiotic anti-microbial activity against Streptococcus iniae in red hybrid tilapia. METHODS AND RESULTS Abnormal behavior, clinical signs, post-injection survival, and histopathology (kidney, liver, eye, and brain) were measured. Cumulative mortality of CON+ , free cells, ALG, and treatments (F1-F7) was 30, 24, 22, 19, 17, 17, 16, 14, 14, and 12 out of 30 fish and the survival rates for E. faecium ABRIINW.N7 microencapsulated in an alginate-BS blend with 0.5%, 1%, 1.5%, 2%, 2.5%, and 3% fenugreek were 43%, 43%, 47%, 53%, 53% and 60%, respectively. After the incorporation of fenugreek with the alginate-BS blend, there was an 8-21% increase in probiotic cell viability. Furthermore, the survival rate for the alginate-BS blend with 2.5% and 3% fenugreek (F6 and F7) was significantly (P≤0.05) higher than other blends. The highest encapsulation efficiency, viability in gastrointestinal conditions and during storage time, and excellent anti-pathogenicity against S. iniae were observed in alginate-BS + 3% fenugreek formulation (F7). CONCLUSIONS It is recommended that probiotic strains like E. faecium ABRIINW.N7 in combination with local herbal gums, such as BS and fenugreek plus alginate, can be used as a suitable scaffold and an ideal matrix for the encapsulation of probiotics. SIGNIFICANCE AND IMPACT OF STUDY This study proposes models connecting process parameters, matrix structure, and functionality.