Gut Microbial Changes, Interactions, and Their Implications on Human Lifecycle: An Ageing Perspective

Table 1

Changes in the gut microbiota in the healthy ageing (natural, non-antibiotic treated).

Study details	Sample details	Methods	Changes	Ref
Comparative study	= 30; (i) Rural (high fibre diet) = 15 median age 84; (ii) Urban (low fibre diet) = 15 median age 68	Culture based; analysis	(i) Rural: High in Bifidobacteria, Bacilli and mainly Clostridium perfringens; (ii) Urban: Low Bifidobacterium adolescentis and Fusobacterium mortiferum strains	[13]
Analysis of gut microbiota	= 6	16S rRNA gene sequencing, culture-based	(i) Bacteroides, Gamma-Proteobacteria and Clostridium IV, IX, XIVa dominated	[14]
Characterization of jejunal, ileal, caecal and rectosigmoidal colonic microbiota	= 3; (i) Colon autopsy samples	16S rRNA gene sequencing	(i) Jejunal and Ileal microbiota: streptococci, lactobacilli, Gammaproteobacteria, the Enterococcus group and the Bacteroides; (ii) Caecum: Bacteroides, Clostridium; (iii) Sigmoid-colon: C. coccoides group, the C. leptum subgroup, the Bacteroidetes group, Gammaproteobacteria, the Bifidobacterium, streptococci and lactobacilli groups	[15]
Cross-sectional; study	= 230; (i) Sweden, adults (SA) = 20, elderly (SE) = 40; (ii) Germany (GA), adults = 23, elderly (GA) = 38; (iii) France, adults (FA) = 22, elderly (FE) = 27; (iv) Italy, adults (IA) = 30, elderly (IE) = 40	FISH and flow cytometry	(i) SA: Eubacterium rectale-Clostridium coccoides low in number High Lactobacillus-enterococcus group in both SA and SE; (ii) GE: Eu., rectale-C. coccoides cluster higher; (iii) FA: low levels of Bacteroides-Prevotella group. Low levels of bifidobacteria trend in FE; (iv) IA & IE: lowest levels of Lactobacillus-enterococcus group. High Bifidobacterium group; (v) High enterobacteria levels in all countries in the elderly	[16]
Observational study	= 249; (i) Infants = 150, age 1 to 12 months; (ii) Adults = 54, age 25 to 35 years; (iii) Elderly = 45, age 80 to 82 years.	16S rRNA gene sequencing and FISH analysis	(i) Akkermansia muciniphila is present and colonizes the intestinal tract in early life and develops within a year to a level close to that observed in healthy adults	[17]
Comparative assessment of faecal microbiota	= 62; (i) Infants, = 21, age 3 weeks to 10 months; (ii) Adults, = 21, age 25 to 45 years; (iii) Elderly, = 20, age 70 to 90 years	qPCR and 16S rRNA gene sequencing	Firmicutes to Bacteroidetes ratios (in log10): (i) Infants: 0.4; (ii) Adults: 10.9; (iii) Elderly: 0.6	[18]
Comparative analysis	= 84; (i) Adults = 20, age 25 to 40 years; (ii) Elderly = 22, age 63 to 76 years; (iii) Centenarians = 21, age 99 to 104 years.	16S rRNA gene sequencing	(i) Adults and Elderly: Bacteroidetes and Firmicutes dominant; low levels of Actinobacteria, and Proteobacteria; (ii) Centenarians: High levels of Proteobacteria; decrease in Clostridium cluster XIVa, an increase in Bacillus species	[6]

sorted by year of publication; FISH: fluorescence in situ hybridization.