DIATOMS AND HGT. “Besides providing evidence for the ancient secondary endosymbiotic event at the origin of diatoms (and perhaps all chromalveolates), it was found that diatom genomes also contain a large number of genes (587 in P. tricornutum) proposed to be derived from bacteria by horizontal gene transfer.” (HGT = Horizontal Gene Transfer).
http://jxb.oxfordjournals.org/content/early/2012/01/20/jxb.err441.full