Optimization of low cost culture media for the production of biomass and bacteriocin by a potentially urogenital probiotic Lactobacillus salivarius strain

MARÍA SILVINA JUÁREZ TOMÁS; ELENA BRU; BIRGITT WIESE; MARÍA ELENA NADER- MACÍAS

Saint-Malo, Francia.

Simposio; Second International Symposium on Antimicrobial Peptides. AMP 2009.; 2009

Organizado por French Research Institute INRA (Research Unit for Food Safety and Microbiology) en colaboración con French Food Safety Agency (AFSSA)

Microbial biomass is one of the bioactive compounds that can be considered as raw material for probiotic products that must be administered in high quantities and in viable way to produce the beneficial effect aimed. Antimicrobial peptides synthesized by bacteria can be also incorporated together with probiotic live bacteria, increasing the inhibitory action spectrum on pathogens. The aim of this work was to formulate a culture medium of lower cost than conventional laboratory media, in order to simultaneously obtain high amount of biomass and bacteriocin of vaginal Lactobacillus salivarius CRL 1328. The growth assays under different culture conditions were performed by using a fractional composite design 28-2. The factors and levels taken into consideration were: glucose (0 and 20 g/l), lactose (0 and 20g/l), yeast extract (0 and 20g/l), tryptone (0 and 20g/l), ammonium citrate (0 and 2g/l), sodium acetate (0 and 5g/l), MgSO4.7H20 (0 and 0.1g/l) and MnSO4.H20 (0 and 0.05g/l). Ten replicates at the central points (all the nutrients at a half concentration between the higher and lower levels) and 16 star points were included. Samples were taken at specific time intervals to determine the growth (optical density at 540 nm) and the bacteriocin titres (by the plate method assay), by using vaginal Enterococcus faecalis MP97 as indicator strain. [1] The desirability function approach was used to predict the optimal medium compositions to get the higher biomass and bacteriocin production in the experimental conditions assayed.    The results indicate that the growth and bacteriocin production was dependent on the composition of the different culture media evaluated. The simultaneous presence of a carbon source (mainly glucose), a nitrogen sources (mainly yeast extract) and salts (mainly MnSO4, MgSO4 and sodium acetate) allowed to reach the highest cell biomass and bacteriocin levels recorded in the experimental design [OD540 nm = 1.28 ± 0.07 and log (AU/ml) = 3.03, respectively]. Through the application of the desirability function, several optimal medium compositions to achieve efficient production of biomass and bacteriocin were predicted: glucose (19.20-20 g/l), lactose (0-5.25 g/l), yeast extract (18.69-19.95 g/l), tryptone (11.96-18.82 g/l), ammonium citrate (0.12-0.70 g/l), sodium acetate (2.76-4.87 g/l), MgSO4 (0.06-0.10 g/l) and MnSO4 (0.03-0.05). Similar growth and amounts of bacteriocin were obtained in some of the media assayed when compared with standard MRS and LAPTg broths, lowering their cost around 25 to 60% by the adequate combination of ingredients. The results represent an advance in the search of the most suitable strategies for the production of bioactive compounds for pharmaceutical products to prevent or treat female urogenital infections. References. [1] Juárez Tomás MS, Bru E, Wiese B, De Ruiz Holgado AP & Nader-Macías ME (2002) Influence of pH, temperature and culture media on the growth and bacteriocin production of vaginal Lactobacillus salivarius CRL 1328. J Appl Microbiol 93: 714-724. [1] Juárez Tomás MS, Bru E, Wiese B, De Ruiz Holgado AP & Nader-Macías ME (2002) Influence of pH, temperature and culture media on the growth and bacteriocin production of vaginal Lactobacillus salivarius CRL 1328. J Appl Microbiol 93: 714-724.