Objective: The colonic microbiota is altered in patients with colorectal cancer (CRC). We investigated the microbiota composition of patients with colon cancer compared with controls devoid of neoplastic or inflammatory disease and the potential to modify the colonic microbiota with probiotics. Design: Biopsy samples were obtained from the normal mucosa and tumour during colonoscopy from 15 patients with colon cancer. Subsequent patient-matched samples were taken at surgery from the tumour and nearby mucosa from the patients with cancer, eight of whom had received two daily tablets totalling 1.4×10¹⁰ CFUs Bifidobacterium lactis Bl-04 and 7×10⁹ CFUs Lactobacillus acidophilus NCFM. Faecal samples were obtained after colonoscopy prior to starting the intervention and at surgery. In addition, 21 mucosal biopsies from non-cancer controls were obtained during colonoscopy followed by later faecal samples. The colonic and faecal microbiota was assessed by 16S rRNA gene amplicon sequencing. Results: The tumour microbiota was characterised by increased microbial diversity and enrichment of several taxa including Fusobacterium, Selenomonas and Peptostreptococcus compared with the control microbiota. Patients with colon cancer that received probiotics had an increased abundance of butyrate-producing bacteria, especially Faecalibacterium and Clostridiales spp in the tumour, non-tumour mucosa and faecal microbiota. CRC-associated genera such as Fusobacterium and Peptostreptococcus tended to be reduced in the faecal microbiota of patients that received probiotics. Conclusions: Patients with colon cancer harbour a distinct microbiota signature in the tumour tissue and nearby mucosa, which was altered with probiotic intervention. Our results show promise for potential therapeutic benefits in CRC by manipulation of the microbiota. Trial registration number: NCT03072641; Results.

Probiotics are live microorganisms, mainly belonging to the genera Lactobacillus and Bifidobacterium, although also strain of other species are commercialized, that have a beneficial effect on the host. From the perspective of antibiotic use, probiotics have been observed to reduce the risk of certain infectious disease such as certain types of diarrhea and respiratory tract infection. This may be accompanied with a reduced need of antibiotics for secondary infections. Antibiotics tend to be effective against most common diseases, but increasingly resistance is being observed among pathogens. Probiotics are specifically selected to not contribute to the spread of antibiotic resistance and not carry transferable antibiotic resistance. Concomitant use of probiotics with antibiotics has been observed to reduce the incidence, duration and/or severity of antibiotic-associated diarrhea. This contributes to better adherence to the antibiotic prescription and thereby reduces the evolution of resistance. To what extent probiotics directly reduce the spread of antibiotic resistance is still much under investigation; but maintaining a balanced microbiota during antibiotic use may certainly provide opportunities for reducing the spread of resistances. Key messages Probiotics may reduce the risk for certain infectious diseases and thereby reduce the need for antibiotics. Probiotics may reduce the risk for antibiotic-associated diarrhea Probiotics do not contribute to the spread of antibiotic resistance and may even reduce it.

The gut microbiota contributes to host energy metabolism, and altered gut microbiota has been associated with obesity-related metabolic disorders. We previously reported that a probiotic alone or together with a prebiotic controls body fat mass in healthy overweight or obese individuals in a randomised, double-blind, placebo controlled clinical study (ClinicalTrials.gov NCT01978691). We now aimed to investigate whether changes in the gut microbiota may be associated with the observed clinical benefits. Faecal and plasma samples were obtained from a protocol compliant subset (n=134) of participants from a larger clinical study where participants were randomised (1:1:1:1) into four groups: (1) placebo, 12 g/d microcrystalline cellulose; (2) Litesse® Ultra™ polydextrose (LU), 12 g/day; (3) Bifidobacterium animalis subsp. lactis 420™ (B420), 10¹⁰ cfu/d in 12 g microcrystalline cellulose; (4) LU+B420, 1010 cfu/d of B420 in 12 g/d LU for 6 months of intervention. The faecal microbiota composition and metabolites were assessed as exploratory outcomes at baseline, 2, 4, 6 months, and +1 month post-intervention and correlated to obesity-related clinical outcomes. Lactobacillus and Akkermansia were more abundant with B420 at the end of the intervention. LU+B420 increased Akkermansia, Christensenellaceae and Methanobrevibacter, while Paraprevotella was reduced. Christensenellaceae was consistently increased in the LU and LU+B420 groups across the intervention time points, and correlated negatively to waist-hip ratio and energy intake at baseline, and waist-area body fat mass after 6 months treatment with LU+B420. Functional metagenome predictions indicated alterations in pathways related to cellular processes and metabolism. Plasma bile acids glycocholic acid, glycoursodeoxycholic acid, and taurohyodeoxycholic acid and tauroursodeoxycholic acid were reduced in LU+B420 compared to Placebo. Consumption of B420 and its combination with LU resulted in alterations of the gut microbiota and its metabolism, and may support improved gut barrier function and obesity-related markers.

Background: Diet is a major factor influencing the composition and metabolic activity of the gut microbiota.Objective: This study investigated the eff

Human milk oligosaccharides (HMOs) shape gut microbiota during infancy by acting as fermentable energy source. Using a semi-continuous colon simulator, effect of an HMO, 2′-fucosyllactose (2′-FL), on composition of the infant microbiota and microbial metabolites was evaluated in comparison to galacto-oligosaccharide (GOS) and lactose and control without additional carbon source. Data was analysed according to faecal sample donor feeding type: breast-fed (BF) or formula-fed (FF), and to rate of 2′-FL fermentation: fast or slow. Variation was found between the simulations in the ability to utilise 2′-FL. The predominant phyla regulated by 2′-FL, GOS and lactose were significant increase in Firmicutes, numerical in Actinobacteria, and numerical decrease in Proteobacteria compared to control. Verrucomicrobia increased in FF accounted forAkkermansia, whereas in fast-fermenting simulations Actinobacteria increased with trend for higherBifidobacterium, and Proteobacteria decrease accounted forEnterobacteriaceae. Short-chain fatty acids and lactic acid with 2′-FL were produced in intermediate levels being between ones generated by the control and GOS or lactose. In 2′-FL fast-fermenting group, acetic acid specifically increased with 2′-FL, whereas lactose and GOS also increased lactic acid. The results highlight specificity of 2′-FL as energy source for only certain microbes over GOS and lactose in the simulated gut model.

Recent advances in microbiome research have brought renewed focus on beneficial bacteria, many of which are available in food and dietary supplements. Although probiotics have historically been defined as microorganisms that convey health benefits when ingested in sufficient viable amounts, this description now includes the stipulation “well defined strains,” encompassing definitive taxonomy for consumer consideration and regulatory oversight. Here, we evaluated 52 commercial dietary supplements covering a range of labeled species, and determined their content using plate counting, targeted genotyping. Additionally, strain identities were assessed using methods recently published by the United States Pharmacopeial Convention. We also determined the relative abundance of individual bacteria by high-throughput sequencing (HTS) of the 16S rRNA sequence using paired-end 2x250bp Illumina MiSeq technology. Using multiple methods, we tested the hypothesis that products do contain the quantitative amount of labeled bacteria, and qualitative list of labeled microbial species. We found that 17 samples (33%) were below label claim for CFU prior to their expiration dates. A multiplexed-PCR scheme showed that only 30/52 (58%) of the products contained a correctly labeled classification, with issues encompassing incorrect taxonomy, missing species and un-labeled species. The HTS revealed that many blended products consisted predominantly of Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis. These results highlight the need for reliable methods to qualitatively determine the correct taxonomy and quantitatively ascertain the relative amounts of mixed microbial populations in commercial probiotic products.