The difference in gut microbiota composition between individuals following vegan or vegetarian diets and those following omnivorous diets is well documented. A plant-based diet appears to be beneficial for human health by promoting the development of more diverse and stable microbial systems. Additionally, vegans and vegetarians have significantly higher counts of certain Bacteroidetes-related operational taxonomic units compared to omnivores. Fibers (that is, non-digestible carbohydrates, found exclusively in plants) most consistently increase lactic acid bacteria, such as Ruminococcus, E. rectale, and Roseburia, and reduce Clostridium and Enterococcus species. Polyphenols, also abundant in plant foods, increase Bifidobacterium and Lactobacillus, which provide anti-pathogenic and anti-inflammatory effects and cardiovascular protection. High fiber intake also encourages the growth of species that ferment fiber into metabolites as short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate. The positive health effects of SCFAs are myriad, including improved immunity against pathogens, blood–brain barrier integrity, provision of energy substrates, and regulation of critical functions of the intestine. In conclusion, the available literature suggests that a vegetarian/vegan diet is effective in promoting a diverse ecosystem of beneficial bacteria to support both human gut microbiome and overall health. This review will focus on effects of different diets and nutrient contents, particularly plant-based diets, on the gut microbiota composition and production of microbial metabolites affecting the host health.

Antimicrobials used in salmon aquaculture pass into the marine environment. This could have negative impacts on marine environmental biodiversity, and on terrestrial animal and human health as a result of selection for bacteria containing antimicrobial resistance genes. We therefore measured the numbers of culturable bacteria and antimicrobial-resistant bacteria in marine sediments in the Calbuco Archipelago, Chile, over 12-month period at a salmon aquaculture site approximately 20 m from a salmon farm and at a control site 8 km distant without observable aquaculture activities. Three antimicrobials extensively used in Chilean salmon aquaculture (oxytetracycline, oxolinic acid, and florfenicol) were studied. Although none of these antimicrobials was detected in sediments from either site, traces of flumequine, a fluoroquinolone antimicrobial also widely used in Chile, were present in sediments from both sites during this period. There were significant increases in bacterial numbers and antimicrobial-resistant fractions to oxytetracycline, oxolinic acid, and florfenicol in sediments from the aquaculture site compared to those from the control site. Interestingly, there were similar numbers of presumably plasmid-mediated resistance genes for oxytetracycline, oxolinic acid and florfenicol in unselected marine bacteria isolated from both aquaculture and control sites. These preliminary findings in one location may suggest that the current use of large amounts of antimicrobials in Chilean aquaculture has the potential to select for antimicrobial-resistant bacteria in marine sediments.

Summary: B orrelia burgdorferi sensu lato (s.l.), transmitted by I xodes spp. ticks, is the causative agent of L yme disease. Although I xodes spp. ticks are distributed in both N orthern and S outhern H emispheres, evidence for the presence of B . burgdorferi s.l. in S outh A merica apart from U ruguay is lacking. We now report the presence of culturable spirochetes with flat‐wave morphology and borrelial DNA in endemic I xodes stilesi ticks collected in C hile from environmental vegetation and long‐tailed rice rats ( O ligoryzomys longicaudatus ). Cultured spirochetes and borrelial DNA in ticks were characterized by multilocus sequence typing and by sequencing five other loci (16 S and 23 S ribosomal genes, 5 S –23 S intergenic spacer, flaB , ospC ). Phylogenetic analysis placed this spirochete as a new genospecies within the L yme borreliosis group. Its plasmid profile determined by polymerase chain reaction and pulsed‐field gel electrophoresis differed from that of B . burgdorferi B 31 A 3. We propose naming this new S outh A merican member of the L yme borreliosis group B . chilensis VA 1 in honor of its country of origin.