Optimization of probiotic lactobacilli production for in-feed supplementation to feedlot cattle

ARISTIMUÑO FICOSECCO, MARÍA CECILIA; MANSILLA FLAVIA; GRACIELA VIGNOLO; FÁTIMA NADER-MACIAS, MARÍA E.

JOURNAL OF APPLIED MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2023

1364-5072

The selection of probiotic bacteria on the basis of their beneficial characteristics does not imply they can later be scaled up and used for technological applications and formula design. Three probiotic strains, Lactobacillus acidophilus CRL2074, Limosilactobacillusfermentum CRL2085 and Limosolactobacillus mucosae CRL2069 originally isolated from feedlot cattle feces, have demonstrated beneficial characteristics to be applied as in-feed probiotics. Therefore, the current study was conducted to develop a low-cost culture medium to optimize the growth conditions for enhancing the biomass production and to select appropriate cryoprotective agents to sustain functional high cell numbers after freeze-drying. A central composite design was applied to determine the optimal medium composition and a simplified low cost effective media containing 3% molasses and in-dustrial yeast extracts (0.5 to 2.5%) as carbon and nitrogen sources added to a basal medium for each strain, was obtained. Established production conditions at 37 ºC without agitation, pH-controlled for CRL2085 and CRL2069 strains and free pH for CRL2074 probiotics allowed to obtain biomass yields of 12.95, 18.20 and 12.25 g respectively, at 24 h incubation, compared to MRS medium. In addition, the cryoprotective effect of the selected agents showed to be strain-dependent. Thus, the highest viability (109-1010 CFU/g), stability during 30-d storage and survival rate (88-99%) were achieved when 10% MSG (monosodium glutamate); sucrose+fructose+threhalose+WPC (whey protein concentrate) +10% MSG and 1.2% WPC + 10% trehalose were used for freeze-drying CRL2074, CRL2085 and CRL2069, respectively. Moreover, probiotic strains were shown to retain their probiotic functionality when hydrophobic characteristics were evaluated. These results highlight the requirement to perform strain-specific evaluation of the critical factors involved in large-scale production of probiotic lactobacilli to sustain viability and stability after the freeze-drying and storage processes.