and increased gut microbiota diversity and functionality, and mitigated , in a mouse model.

Probiotics should bring 'balance' to the intestinal microbiota by stimulating beneficial bacteria, whilst mitigating adverse ones. Balance can also be interpreted as high alpha-diversity. Contrary, is often regarded as an adverse component of the resident intestinal microbiota. The aim of the present study was to implement a mouse model for screening of -strains for ability to increase gut-microbiota diversity and to mitigate . Mice were divided into six groups, two dietary control-groups and four groups administered strains of and/or . All animals were pre-treated with antibiotics, and in order to equalise the microbiota from the start. After 7 weeks of administration, the animals were sacrificed: DNA was extracted from caecum tissue, and the microbiota composition was analysed with terminal restriction fragment length polymorphism (T-RFLP) and 16S rRNA gene sequencing. The diversity of the caecal microbiota decreased when the dietary carbohydrate source was limited to corn starch. Conversely, the diversity was restored by -supplements. The tested combinations of two strains exerted different influences, not only on the taxonomic level, but also on the inferred microbiome functions. The mixture of GOS47 and GOS1 showed potential for anti-inflammatory activity and short chain fatty acid production. On the other hand, co-administration of GOS57 and GOS42 significantly decreased the viable count of . These results warrant further investigation of the tested strains as candidates for probiotics. Furthermore, the findings demonstrated that the current experimental animal model is suitable for studies of the effect of bacterial supplements on the gut-microbiota.