Complex sentence: However, that strain was lost in the 20th century and after World War II, yeast was imported from the Groterjan Brewery in Berlin, but the yeast was not well suited for producing Grodziskie and was frequently contaminated with spoilage organisms including Lactobacillus.
Split into simpler sentences: However, that strain was lost in the 20th century and after World War II, yeast was imported from the Groterjan Brewery in Berlin. That yeast was not well suited for producing Grodziskie and was frequently contaminated with spoilage organisms including Lactobacillus.