I don't believe they have ever responded to any claims of bacterial life on other planets, they seem to ignore those as unimportant. Even though in reality it implies that life either arose in other areas of the universe through evolution or that God created bacteria on other planets. The latter option doesn't really make much sense. Why would God create bacteria on planets where no other life resides? What purpose could the bacteria serve?
They would adamantly deny the possibility of any intelligent life on other planets. The reason being that intelligent life on other planets would pretty much blow up the whole bible concept of humans being caught in an epic battle for the sovereignty of the universe.