Rosa María Malave Orrala’s scientific contributions

Vibriosis is a multifactorial disease that causes economic losses in the shrimp farming industry. As part of an ecological approach for its control, aqueous extracts from plants generally recognized as safe (GRAS): Allium sativum (290000 µg mL-1), Camellia sinensis (40000 µg mL-1), Morinda citrifolia (250000 µg mL-1) and Origanum vulgare (50000 µg mL-1) were evaluated for their antibacterial, antioxidant and immunostimulant properties. The study began by evaluating the microbicidal properties of the extracts against shrimp pathogenic Vibrio spp. as well as their antioxidant characteristics. Subsequently, the minimum inhibitory concentration and the minimum bactericidal concentration (MBC) were determined in order to find sublethal working concentrations for a comprehensive anti-virulence strategy. The extracts had the ability to disrupt bioluminescence and/or biofilm formation over a wide range of dilutions below the MBC (about 10 to 50 times); 1450 to 145 µg mL-1 for A. sativum, 2000 to 200 µg mL-1 for C. sinensis, 12500 to 1250 µg mL-1 for M. citrifolia, and 2500 to 250 µg mL-1 for O. vulgare. All plant extracts exhibited antioxidant characteristics, differentially modulating superoxide generation depending on the plant extract, without significantly affecting superoxide generation rates; in this case, at the lowest concentrations tested. The most consistent results were obtained with A. sativum extract, which exhibited powerful properties to remove superoxide from unstimulated hemocytes at concentrations ranging from 14500 to 1.45 µg mL-1. In experimental earthen ponds (400 m2, four replicates per treatment), shrimp treated with plant extracts added to food at immunomodulatory concentrations (A. sativum: 36 µg per g, M. citrifolia: 31 µg per g) exhibited reduced melanosis, moreover shrimp treated with A. sativum had the highest harvest weight. These results indicate that aqueous extracts of A. sativum, C. sinensis, O. vulgare, and M. citrifolia can improve shrimp health due to their antioxidant, immunomodulatory, and antimicrobial properties.