Isolation, characterization, and scale-up of native bacteria from the cattle ruminal microbiome

The Paraguayan meat industry is a key economic pillar and one of the country's main signatures, whereby its productivity depends on strategies that optimize livestock production. Animal supplementation using microorganisms emerges as a sustainable alternative to improve cattle nutrition. In this regard, this study focused on the isolation, characterization, and fermentation using bench-top bioreactors of lactic acid bacteria isolated from the bovine ruminal microbiome. Here, we isolated two strains belonging to the Enterococcaceae family, named here as CR2 and CR3. Their tolerance to different temperature and pH conditions, and growth capacity in alternative media, were evaluated using microplate readers. The isolates showed the highest growth rates in MRS medium, and among alternative media, whey supplemented with glucose (5 g/L) exhibited the best growth parameters. Bench-top fermentation using stir-tank bioreactors showed that, after 72-hour, CR3 reached 25 × 1010 CFU/mL, of biomass in MRS, and 24 × 1010 CFU/mL in supplemented whey, corresponding to 2.95 and 2.0 g/L of biomass, respectively. Although the results are promising, future optimizations could improve process efficiency and its application in animal supplementation, by their evaluation as probiotics. This study demonstrates the feasibility of scaling these microorganisms and their potential for valorizing agro-industrial byproducts such as whey. Thus, it proposes a sustainable and innovative approach to bacterial biomass production, benefiting both the livestock industry and byproduct utilization.