Improvement of duckweed (Azolla microphylla) nutrition by Leuconostoc sp. isolated from Nile tilapia (Oreochromis niloticus)

Probiotics are microbiological agents that can potentially increase fish growth performance and fight microbial disease in aquatic animals. The type of inoculum and fermentation time while improving the duckweed's nutrient content are the determining factors for the fermentation process's success. The research objective was to improve the nutrient content of duckweed (Azolla microphyla) by fermenting with lactic acid bacteria isolated from the intestine of Nile tilapia (Oreochromis niloticus). Lactic acid bacteria were isolated using a deMann Rogosa Sharpe agar supplemented with 0.5% CaCO3. Bacterial colonies that showed a clear zone around were isolated and purified. The pure isolates were tested for the ability to produce protease and cellulase enzymes, by using semi-qualitative methods. The study was conducted experimentally using a completely randomized design with a factorial pattern with two replications. The result of protease and cellulase tests showed that two isolates that can produce the best enzymes were identified molecularly and could be applied for fermenting duckweed. Identification results using molecular techniques showed that isolate A2 was Leuconostoc pseudomesenteroides, and isolate A3 was Leucosnostoc sp. A. microphyla was fermented by Leucosnostoc sp. The proximate and amino acids content was evaluated. The proximate composition of fermented A. microphylla was crude protein 14.19%, fat 1.47%, water 22.65%, and ash 55.47%. Amino acids content in fermented ingredients has increased, especially for essential amino acids. Hence, it was concluded that the nutritional properties of A. microphylla could be improved by Leuconostoc sp. isolated from O. niloticus.