Lactobacillus johnsonii is a species in the genus Lactobacillus[1] identified in 1980 by John L. Johnson, an American microbiologist and his associates.

It is part of the healthy vaginal microbiota and has been identified as having probiotic properties.

[3] The L. johnsonii strain La1 was one of the first cultures to be proposed as a probiotic dairy supplement in 1995 at the Nestlé Research Center, Lausanne.

[4] Although yeast and bacteria have been used in dairy products for fermenting purposes for centuries, the investigation and choice of a microorganism as a fermenting agent based on its health benefits was novel at the time.

[5] Today the probiotic culture is used in the LC1 yogurt products by Nestlé.