Swedish to English Medical Biology (-tech,-chem,micro-) Identifying bacterial strain

"Provet XXXXXXX binder i brunn X (...) men ej i brunn Y (...), detta innebär att provet är en [name of strain]." I gather that the above means, "Sample XXXXXXX binds in ??? X but not in ??? Y, which means that the sample is a [name of strain." I'm still puzzled as to what "brunn" could mean in this context. Somehow "well" doesn't seem plausible, since to me that term carries the connotation of a hole in the ground through which water is drawn. Other possibilities that have occurred to me are "solution" (though I'm not sure "brunn" works here as a synonym of "lösning," a term that appears elsewhere in the document) or "source." Any ideas out there?