Diet and the human gut microbiome : an international review

CITATION: Wilson, A. S. et al. 2020. Diet and the Human Gut Microbiome: An International Review. Digestive diseases and sciences, 65(3):723–740. doi:10.1007/s10620-020-06112-wThe original publication is available at https://www.springer.com/journal/10620This review summarizes the key results of recently published studies on the effects of dietary change and nutritional intervention on the human microbiome from around the world, focusing on the USA, Canada, Europe, Asia, and Africa. It first explores mechanisms that might explain the ability of fiber-rich foods to suppress the incidence and mortality from westernized diseases, notably cancers of the colon, breast, liver, cardiovascular, infectious, and respiratory diseases, diabetes, and obesity (O'Keefe in Lancet Gastroenterol Hepatol 4(12):984-996, 2019; Am J Clin Nutr 110:265-266, 2019). It summarizes studies from Africa which suggest that disturbance of the colonic microbiome may exacerbate chronic malnutrition and growth failure in impoverished communities and highlights the importance of breast feeding. The American section discusses the role of the microbiome in the swelling population of patients with obesity and type 2 diabetes and examines the effects of race, ethnicity, geography, and climate on microbial diversity and metabolism. The studies from Europe and Asia extoll the benefits of whole foods and plant-based diets. The Asian studies examine the worrying changes from low-fat, high-carbohydrate diets to high-fat, low-carbohydrate ones and the increasing appearance of westernized diseases as in Africa and documents the ability of high-fiber traditional Chinese diets to reverse type 2 diabetes and control weight loss. In conclusion, most of the studies reviewed demonstrate clear changes in microbe abundances and in the production of fermentation products, such as short-chain fatty acids and phytochemicals following dietary change, but the significance of the microbiota changes to human health, with the possible exception of the stimulation of butyrogenic taxa by fiber-rich foods, is generally implied and not measured. Further studies are needed to determine how these changes in microbiota composition and metabolism can improve our health and be used to prevent and treat disease.https://pubmed.ncbi.nlm.nih.gov/32060812/Publishers versio

16S rRNA gene sequencing reveals effects of photoperiod on cecal microbiota of broiler roosters

Photoperiod is an important factor in stimulating broiler performance in commercial poultry practice. However, the mechanism by which photoperiod affects the performance of broiler chickens has not been adequately explored. The current study evaluated the effects of three different photoperiod regimes (short day (LD) = 8 h light, control (CTR) = 12.5 h light, and long day (SD) = 16 h light) on the cecal microbiota of broiler roosters by sequencing bacterial 16S rRNA genes. At the phylum level, the dominant bacteria were Firmicutes (CTR: 68%, SD: 69%, LD: 67%) and Bacteroidetes (CTR: 25%, SD: 26%, and LD: 28%). There was a greater abundance of Proteobacteria (p < 0.01) and Cyanobacteria (p < 0.05) in chickens in the LD group than in those in the CTR group. A significantly greater abundance of Actinobacteria was observed in CTR chickens than in SD and LD chickens (p < 0.01). The abundance of Deferribacteres was significantly higher in LD chickens than in SD chickens (p < 0.01). Fusobacteria and Proteobacteria were more abundant in SD chickens than in CTR and LD chickens. The predicted functional properties indicate that cellular processes may be influenced by photoperiod. Conversely, carbohydrate metabolism was enhanced in CTR chickens as compared to that in SD and LD chickens. The current results indicate that different photoperiod regimes may influence the abundance of specific bacterial populations and then contribute to differences in the functional properties of gut microbiota of broiler roosters

The Genetic Assessment of South African Nguni Sheep Breeds Using the Ovine 50K Chip

The indigenous sheep breeds of South Africa, such as the Nguni, are well adapted to different ecological regions throughout the country. This has resulted into different ecotypes. However, it is not clear if the differences among Nguni sheep are genetically distinct. The present study aimed to use the latest technology to assess the genetic relationship between Nguni sheep ecotypes and the relationship to other selected South African breeds using SNP markers. In the current study, 144 South African sheep samples (75 Nguni sheep and 69 mixed-breed sheep as a reference) were genotyped using the OvineSNP50 Bead Chip assay from Illumina. The Nguni consisted of 25 Pedi, 25 Swazi, and 25 Zulu sheep, with the reference group comprising 25 Namaqua, 23 Dorper, and 21 Damara sheep. After quality control of 54,241 SNPs, 48,429 SNPs remained for analysis (MAF > 0.05). There were genetic differences in the Nguni sheep population; notably, the Zulu and Swazi populations clustered together, but with a clear distinction from the Pedi ecotype. Genetic admixtures were detected in the Damara and Dorper sheep. This is most likely a consequence of recent intermixing between indigenous and commercial breeds. The levels of genetic diversity within individual types were generally lower compared to commercial breeds. This study revealed an understanding regarding genetic variation within and among indigenous sheep breeds, which can be used as baseline information for establishing conservation and breeding programmes