- Género Xanthobacter
- Xanthobacter autotrophicus, (Baumgarten et al. 1974) Wiegel et al. 1978
- Género Xanthomonas
- Xanthomonas albilineans, (Ashby 1929) Dowson 1943 emend. van den Mooter and Swings 1990
- CECT
546; Hutchinson 38/2; NCPPB 290
- Xanthomonas axonopodis, Starr and Garces 1950 emend. Vauterin et al. 1995
- CECT
548 T; ATCC 19312; DSM 3585; Dye ZB1; ICPB XA103; ICMP 50; LMG 538; LMG 982; PD 884; PDDCC 50; Starr XA103; VdM 184
- CECT
914; Klement E1388; LMG 836
- Xanthomonas campestris, (Pammel 1895) Dowson 1939 emend. Vauterin et al. 1995
- CECT
97 T; ATCC 33913; Billing P25; BPIC 1656; CCRC 12846; CFBP 2350; CIP 100069; DSM 3586; Dye Q19; LMG 568; PD 282; PDDCC 13; VdM 29
- CECT
4428; IFO 3835; NBRC 3835
- CECT
4480; ATCC 11645; Dye Y01; ICPB XA120; LMG 498; Patel 16; PDDCC 441; strain VdM 12
- Xanthomonas fragariae, Kennedy and King 1962 emend. van den Mooter and Swings 1990
- CECT
549 T; ATCC 33239; CCRC 13206; DSM 3587; ICMP 5715; Kennedy A02; LMG 708; PD 885; PDDCC 5715; strain VdM 56
- Xanthomonas hortorum, Vauterin et al. 1995
- CECT
30304; IVIA 9489.2
- CECT
30305; IVIA 9489.1
- Xanthomonas prunicola, López et al. 2018
- CECT
9404 T; CFBP 8353
- CECT
9405; CFBP 8354
- CECT
9406; CFBP 8355
- Xanthomonas sp
- Xanthomonas translucens, (ex Jones et al. 1917) Vauterin et al. 1995
- CECT
4643 T; ATCC 19319; ICPB XT2; NCPPB 973; PDDCC 5752; strain VdM 130
- Xanthomonas vesicatoria, (ex Doidge 1920) Vauterin et al. 1995
- CECT
792; Dowson 195; Dye X5; LMG 915; PDDCC 67
- Género Xenorhabdus
- Xenorhabdus nematophila, (Poinar and Thomas 1965) Thomas and Poinar 1979
- CECT
4841 T; ATCC 19061; CCEB 786; CCM 7081; CCRC 13945; CCUG 14189; CUETM 83-19; LMG 1036; NCIB 9965
- Género Xylanibacterium
- Xylanibacterium ulmi, Rivas et al. 2004
- CECT
5731 T; XIL08; JCM 14284; LMG 21721
- Género Xylanimonas
- Xylanimonas cellulosilytica, Rivas et al. 2003
- CECT
5975 T; JCM 12276; LMG 20990
- Xylanimonas sp., Rivas et al. 2003
- Género Xylella
- Xylella fastidiosa, Wells et al. 1987
- Xylella fastidiosa subsp. fastidiosa, (Wells et al. 1987) Schaad et al. 2009
- Xylella fastidiosa subsp. multiplex, Schaad et al. 2009
- Género Xylophilus
- Xylophilus ampelinus, (Panagopoulos 1969) Willems et al. 1987
- CECT
7646 T; CECT 547; LMG 5856; NCPPB 2217; VdM 195