Use of clean room equipment at the Japanese farm is not surprising, since that facility was, in fact, a fab[1]. And it is still managed under similar regimen.

Apparently, lack of biological contaminants helps justify a premium price for their produce, since those lettuce can remain fresh on supermarket shelves for a significantly longer duration.

[1] http://www.fujitsu.com/global/about/resources/news/press-rel...