Production of a potential multistrain probiotic in co-culture conditions using agro-industrial by-products-based medium for fish nutrition

Abstract Background Probiotics are viable microorganisms that when administered in adequate amounts confer health benefits to the host. In fish, probiotic administration has improved growth, and immunological parameters. For this reason, it is necessary production of probiotic bacteria, however, commercial culture mediums used for probiotic growth are expensive, so the design of a “low” cost culture medium is necessary. Therefore, this research aimed to produce a potential multistrain probiotic preparation composed of L. lactis A12 and Priestia species isolated from Nile tilapia (Oreochromis niloticus) gut using an agro-industrial by-products-based culture medium. Results A Box-Behnken design with three factors (whey, molasses, and yeast extract concentration) was used. As the main results, a high concentration of three components enhanced the viability of L. lactis A12, however, viable cell counts of Priestia species were achieved at low molasses concentrations. The Optimal conditions were 1.00% w/v whey, 0.50% w/v molasses, and 1.50% w/v yeast extract. L. lactis A12 and Priestia species viable counts were 9.43 and 6.89 Log10 CFU/mL, respectively. L. lactis A12 concentration was higher (p