| Área: Microbiologia Geral ( Divisão H ) ASSIMILATION OF PREBIOTIC CARBOHYDRATES BY LACTOBACILLUS SOBRIUS IN AN IN VITRO MODEL
Haíssa Roberta Cardarelli (FCF/USP); Susana Marta Isay Saad (FCF/USP); Hauke Smidt (WUR)
Resumo
Beneficial effects attributed to probiotics and prebiotics have been extensively studied during the last years; although their mechanisms of action at host level have not been completely elucidated. This study aimed to verify the effect of a potentially probiotic strain of Lactobacillus sobrius, combined or not with prebiotic ingredients (trans-galactooligosaccharides - TOS, fructooligosaccharides – FOS and Konjac glucomannan oligosaccharides - KGMO) on the composition and functionality of human and pig gut microbiota. For this purpose, an in vitro fermentation model was employed, using fecal inocula of three human volunteers (H1, H2 and H3) and three pigs (P1, P2 and P3). Quantification of L. sobrius and total bacterial growth were conducted through 16S rRNA gene-targeted real time PCR analysis. The fermentation was monitored by the determination of short chain fatty acids (SCFA – by HPLC), lactate (HPLC), ammonia (colorimetric assay), carbohydrates assimilation (phenol-sulphuric method) and pH.
L.sobrius populations did not vary significantly (p<0.05), except in the presence of FOS (increased with H3 and decreased with P2 and P3). The utilization of carbohydrates and pH reductions were higher with human inoculum. The lowest pH values were achieved with FOS with both inocula. SCFA accumulations showed less variation intra pig group than intra human group. The fastest accumulation of SCFA with pig inoculum occurred with glucose, and the slowest with FOS, although maximum values were similar. For one human inoculum, there was a negative balance of SCFA accumulation with glucose (H3), and lactic and acetic acids were consumed by the microbiota from 7h to 24h of fermentation, possibly because of a methanogenic metabolism. The highest values of SCFA were obtained with FOS and TOS (H3). Ammonia values reduced mainly during the exponential carbohydrate assimilation with both inocula, although slowly with pig inoculum (except in the presence of FOS). Studies including the expression of genes related to the differential carbohydrates assimilation are recommended, as to unravel the mechanisms employed by L. sobrius and its interaction with the human and porcine intestinal microbiota, allowing, in the future, its use solely or in combination with prebiotics in pro- and symbiotic functional foods.
Palavras-chave: fructooligosaccharides, in vitro model, konjac glucomannan oligosaccharides, Lactobacillus sobrius, trans-galactooligosaccharides |