A process for making a tea based fermented drink, consisting of - separating and selecting a colony of a bacterial strain, wherein the bacterial strain is from a single species selected from the group consisting of Acetobacter aceti, Acetobacter xylinum, Gluconobacter oxydans, and Gluconobacter cerinus; - preparing and selecting a seed liquid from culturing the colony through sequentially a slant surface culture, an initial small scale active liquid culture, and at least one enlarged scale active liquid culture, wherein the seed liquid consists of a culture of the colony of the single species without any contaminating bacteria, and - culturing the seed liquid in a large scale active liquid culture to obtain the tea based fermented drink, wherein; - the slant surface culture is conducted on a solid culture medium containing B vitamins at about 28°C to 30°C for about 48 hours under a pH of about 6.0 to 6.5; - the initial small scale active liquid culture is conducted in a small-scale container at a temperature of about 28°C to 30°C under a pH of about 6.0 to 6.5 under an aerobic condition with continuous air ventilation, and mixing to a uniformly distribute bacteria in the culture liquid for about 18 to 24 hours; - the enlarged scale active liquid culture is conducted in a medium-scale seed liquid preparation tank in a liquid culture medium containing a tea extract by adding of food grade ethanol at a temperature of about 28°C to 30°C under a pH of about 4.8 to 5.2 - the seed liquid is selected at the end of the enlarged scale active liquid culture, wherein the seed liquid has the pH of the culture liquid reduced to a range of about 2.5 to 2.8, an OD at 640nm at about 0.150 to 0.200 at an end of the enlarged scale active liquid culture, and - the large scale active liquid culture is conducted under an aerobic condition with continuous air ventilation, by adding of food grade ethanol and mixing to uniformly distribute bacteria at about 28°C to 30°C, air ventilation rate of about 0.5 v/v/m, and under a starting pH of about 4.8 to 5.2 for less than about 30 hours, and having the pH reduced to about 2.6 to 2.8 and an OD at 640nm at about 0.10 to 0.13 within less than 30 hours for the large scale active liquid culture to obtain the tea-based fermented drink. - separating and selecting a colony of a bacterial strain, wherein the bacterial strain is from a single species selected from the group consisting of Acetobacter aceti, Acetobacter xylinum, Gluconobacter oxydans, and Gluconobacter cerinus; - preparing and selecting a seed liquid from culturing the colony through sequentially a slant surface culture, an initial small scale active liquid culture, and at least one enlarged scale active liquid culture, wherein the seed liquid consists of a culture of the colony of the single species without any contaminating bacteria, and - culturing the seed liquid in a large scale active liquid culture to obtain the tea based fermented drink, wherein; - the slant surface culture is conducted on a solid culture medium containing B vitamins at about 28°C to 30°C for about 48 hours under a pH of about 6.0 to 6.5; - the initial small scale active liquid culture is conducted in a small-scale container at a temperature of about 28°C to 30°C under a pH of about 6.0 to 6.5 under an aerobic condition with continuous air ventilation, and mixing to a uniformly distribute bacteria in the culture liquid for about 18 to 24 hours; - the enlarged scale active liquid culture is conducted in a medium-scale seed liquid preparation tank in a liquid culture medium containing a tea extract by adding of food grade ethanol at a temperature of about 28°C to 30°C under a pH of about 4.8 to 5.2 - the seed liquid is selected at the end of the enlarged scale active liquid culture, wherein the seed liquid has the pH of the culture liquid reduced to a range of about 2.5 to 2.8, an OD at 640nm at about 0.150 to 0.200 at an end of the enlarged scale active liquid culture, and - the large scale active liquid culture is conducted under an aerobic condition with continuous air ventilation, by adding of food grade ethanol and mixing to uniformly distribute bacteria at about 28°C to 30°C, air ventilation rate of about 0.5 v/v/m, and under a starting pH of about 4.8 to 5.2 for less than about 30 hours, and having the pH reduced to about 2.6 to 2.8 and an OD at 640nm at about 0.10 to 0.13 within less than 30 hours for the large scale active liquid culture to obtain the tea-based fermented drink.