good bacterial flora. lactobacilli, bifidobacteria, escherichia

acid acidophilus bacillus bacteria bacterial bacteriology bacterium bad bifidobacteria biological biology body care coli colon design digestion digestive enteric escherichia fermentation flat flora germ good gut health healthy human icon illustration infection intestinal intestine isolated lactic lactobacillus medical medicine microbe microbiology microflora microorganism microscopic organ prebiotic probiotic probiotics vector