Table 2. New HGT events for each Se utilization trait.

Se trait	From (donor)	To (recipient)	Occurrence of other Se trait in recipient
Sec	Microlunatus phosphovorus NM-1 (Actinobacteria/Propionibacterineae)	Arthrobacter crystallopoietes BAB-32 (Actinobacteria/Micrococcineae)	—
	Nakamurella multipartita DSM 44233 (Actinobacteria/Frankineae)	Arthrobacter sp. 162MFSha1.1 (Actinobacteria/Micrococcineae)	—
	Pseudomonas stutzeri A1501 (Gammaproteobacteria/Pseudomonadales)	Marinobacter daepoensis DSM 16072 (Gammaproteobacteria/Alteromonadales)	SeU
	Aeromonas hydrophila pc104A (Gammaproteobacteria/Aeromonadales)	Psychromonas sp. CNPT3 (Gammaproteobacteria/Alteromonadales)	SeU
SeU	Bacillales species (Firmicutes/Bacillales)	Lacticigenium naphtae DSM 19658 (Firmicutes/Lactobacillales)	—
Se-cofactor	Clostridium species (Firmicutes/Clostridia)	Fusobacterium sp. 11_3_2 (Fusobacteria)	—
	Clostridium species (Firmicutes/Clostridia)	Treponema phagedenis F0421 (Spirochaetes)	—

Abbreviation: HGT, horizontal gene transfer.