Microcultures of lactic acid bacteria: characterization and selection of strains, optimization of nutrients and gallic acid concentration

Abstract

Eighteen lactic acid bacteria (LAB) strains, isolated from coffee pulp silages were characterized according to both growth and gallic acid (GA) consumption. Prussian blue method was adapted to 96-well microplates to quantify GA in LAB microcultures. Normalized data of growth and GA consumption were used to characterize strains into four phenotypes. A number of 5 LAB strains showed more than 60% of tolerance to GA at 2 g/l; whereas at 10 g/l GA growth inhibition was detected to a different extent depending on each strain, although GA consumption was observed in seven studied strains (>60%). Lactobacillus plantarum L-08 was selected for further studies based on its capacity to degrade GA at 10 g/l (97%). MRS broth and GA concentrations were varied to study the effect on growth of LAB. Cell density and growth rate were optimized by response surface methodology and kinetic analysis. Maximum growth was attained after 7.5 h of cultivation, with a dilution factor of 1-1/2 and a GA concentration between 0.625 and 2.5 g/l. Results indicated that the main factor affecting LAB growth was GA concentration. The main contribution of this study was to propose a novel adaptation of a methodology to characterize and select LAB strains with detoxifying potential of simple phenolics based on GA consumption and tolerance. In addition, the methodology presented in this study integrated the well-known RSM with an experimental design based on successive dilutions.

Influence of gallic acid and catechin polyphenols on probiotic properties of Streptococcus thermophilus CHCC 3534 strain

“…Such interactions have the potentially to decrease the number of probiotic cells available for beneficial activity in the gut (Ranadheera et al 2010), or change the composition of GItract resident flora in an unexpected way (PuupponenPimiä et al 2005). Some species of lactic acid bacteria (LAB) grow well in plant-derived food substrates (Rodríguez et al 2009), but also can be metabolically suppressed by phenolic compounds (Guzmán-López et al 2009). Catechin and gallic acid have been reported to have inhibited Lactobacillus plantarum in wine (Landete et al 2007).…”

Molecular assessment of microbiota structure and dynamics along mixed olive oil and winery wastewaters biotreatment

“…The capacity to decrease the redox potential and to promote the inverse reaction of auto-oxidation of phenolic compounds to tannins present in OOWW, by reductive depolymerisation of polyphenols, leads to decolourization and biodegradation of these compounds (Ayed and Hamdi 2003). Based on the capacity to degrade 97% of gallic acid, a L. plantarum strain was selected by Guzmán-López et al (2009) for further studies about the effect of phenolic compounds in growth of lactic acid bacteria.…”