Table 1.

Microbial composition of water kefir beverages.

Origin	Substrates and fermentation	Technique	Main species	Reference
Malaysia	−18 g WKG, 50 g organic raw sugar and 500 mL of mineral water. −24 h at room temperature	16S rRNA sequencing	Lb. hilgardii, Lb. harbinensis, Acetobacter lovaniensis, Lb. satsumensis, Acetobacter tropicalis, Lb. zeae, Oenococcus oeni	[16]
Argentina	−10 g WKG, 100 mL sugar solution -Three sugar solutions; 5 % (w/v) brown sugar, 6.5 % (w/v) purified molasses and 6.5 % (w/v) high-test molasses	16S rRNA sequencing	Brown sugar and purified molasses: Lb. nagelii High-test molasses: Lb. hilgardii/diolivorans and Lb. casei/paracasei	[17]
Japan	−10 g WKG, 100 mL sugar solution -Three sugar solutions; 5 % (w/v) brown sugar, 6.5 % (w/v) purified molasses and 6.5 % (w/v) high-test molasses −24 h at room temperature	16S rRNA sequencing	Brown sugar: Lb. nagelii, S. cerevisiae, A.tropicalis Purified molasses: A. tropicalis, Lb. farraginis, Lb. satsumensis, Oenococcus kitaharae, Lb. casei/paracasei, Lb. nagelii, Lb. harbinensis, Pichia occidentali, S. cerevisiae High-test molasses: A. Indonesiensis, Lb. casei/paracasei, Lb. diolivorans, Lb. farraginis, Lb. harbinensis, Pichia membranifaciens, S. cerevisiae Species isolated from kefir beverage for the first time: Acetobacter indonesiensis, Acetobacter tropicalis, Gluconobacter oxydans, Lb. farraginis, Oenococcus kitaharae, and Pichia occidentalis	[15]
Belgium	-Unrefined cane sugar (7.1 %, m/v) and fig extract (17.6 %, v/v) −15 g WKG, 85 mL water kefir simulation medium	Shotgun metagenomic sequencing	Bifidobacterium aquikefiri, Lb. harbinensis, Lb. hilgardii, Lb. nagelii, Lb. paracasei, Oenococcus oeni, Oenococcus kitaharae Saccharomyces cerevisiae, Dekkera bruxellensis,	[13]
Canada, the United Kingdom, the United States	−60 g grains per L of sterilised mineral water −10 % sucrose, one dried, organic fig −24 h at room temperature	Culture-independent	-Zymomonas was the dominant component followed by lactic acid bacteria (Lactobacillus and Leuconostoc) and acetic acid bacteria (Acetobacter and Gluconacetobacter). -Bifidobacteriaceae was at low proportions.	[18]
Germany	-Four different home-made grains -Mineral with 100g/L fig extract and 80 g/L sucrose −72 h at 21 °C	16S rRNA sequencing	Lactobacillus, Leuconostoc, Acetobacter, Gluconobacter, Bifidobacterium (Bifidobacterium psychraerophilum)	[19]
Turkey	-WKG 5 % (w/w) added to Rosehip, Cornelian cherry, pomegranate, red plum, and hawthorn juices −48 h at room Temperature	Culture dependent	-Rosehip kefir: highest Lactobacillus spp., and Lactococcus spp. -Cornelian Cherry and hawthorn kefir: yeast counts increased	[20]
Belgium	−15 g WKG, 85 mL of autoclaved water kefir simulation medium −6 g unrefined cane sugar, 65 mL of distilled water and 20 mL of fig extract	Culture-independent	Lb. paracasei, Lb. hilgardii, Lb. nagelii and S. cerevisiae	[21]
Germany	-Homemade WKGs −1 L tap water, sucrose solution (100 g/L), two dry figs and a slice of organic lemon −72 h at 21 °C	16S rRNA sequencing	Lb. hordei, Lb. nagelii, Lc. mesenteroides, Lc. citreum, Acetobacter fabarum, Acetobacter Orientalis, S. cerevisiae, Lachancea fermentati, Hanseniaspora valbyensis, Zygotorulaspora florentina	[22]

16S rDNA: 16S ribosomal RNA gene; WKG: water kefir grain.