Novel chlamydiae in whiteflies and scale insects: endosymbionts ‘Candidatus Fritschea bemisiae’ strain Falk and ‘Candidatus Fritschea eriococci’ strain Elm Karin D. E. Everett, 1 MyLo Thao, 2 Matthias Horn, 3 Glen E. Dyszynski 4 and Paul Baumann 2 Correspondence Karin D. E. Everett kdeeverett@hotmail.com or kdee2004@u.washington.edu or keverett@uga.edu 1 Department of Biology, Box 355325, University of Washington, Seattle, WA 98195-5325, USA 2 Microbiology Section, University of California, Davis, CA 95616-8665, USA 3 Division of Microbial Ecology, Institute of Ecology and Conservation Biology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria 4 University of Georgia, Athens, GA 30602, USA Bacteria called ‘Fritschea’ are endosymbionts of the plant-feeding whitefly Bemisia tabaci and scale insect Eriococcus spurius. In the gut of B. tabaci, these bacteria live within bacteriocyte cells that are transmitted directly from the parent to oocytes. Whiteflies cause serious economic damage to many agricultural crops; B. tabaci fecundity and host range are less than those of Bemisia argentifolii, possibly due to the presence of this endosymbiont. The B. tabaci endosymbiont has been characterized using electron microscopy and DNA analysis but has not been isolated or propagated outside of insects. The present study compared sequences for 11 endosymbiont genes to genomic data for chlamydial families Parachlamydiaceae, Chlamydiaceae and Simkaniaceae and to 16S rRNA gene signature sequences from 330 chlamydiae. We concluded that it was appropriate to propose ‘Candidatus Fritschea bemisiae’ strain Falk and ‘Candidatus Fritschea eriococci’ strain Elm as members of the family Simkaniaceae in the Chlamydiales. The whitefly Bemisia tabaci biotype A contains several types of endosymbiont (Costa et al., 1995). Two have been characterized, including rRNA gene sequence analyses (Clark et al., 1992; Thao & Baumann, 2004a; Zchori-Fein & Brown, 2002). The third endosymbiont, when examined using electron microscopy (EM), has a biphasic appearance (Fig. 1). The electron-dense globular bodies of the bipha- sic endosymbiont are 0?2–0?25 mm wide and the less dense morphological forms are 0?7–0?8 mm wide and 0?7–2?5 mm long (Costa et al., 1995). The chlamydial nature of the biphasic endosymbiont is suggested by PCR amplification of extracted total insect DNA using 23S rRNA gene signa- ture sequence primers (Thao et al., 2003; Everett et al., 1999a). Analysing a 16?6 kb XhoI–EcoRV genome segment from the organism, Thao et al. (2003) found that the full- length 16S rRNA and 23S rRNA gene sequences were 91 % identical to rRNA genes in Simkania negevensis Z T , the type strain, species and genus of the Simkaniaceae (Table 1), and that, like S. negevensis, the 23S rRNA gene contained an intron (Everett et al., 1999b). Although the endosymbiont was not isolated, Thao et al. (2003) proposed the names ‘Fritschea bemisiae’ for the endosymbiont and ‘Fritschea eriococci’ for a related endosymbiont. A bacterial species must be culturable for valid publica- tion of its name. The B. tabaci chlamydial endosymbiont, however, has only been found to live in bacteriocytes, which are transmitted vertically to oocytes (Costa et al., 1996). In an effort to culture this endosymbiont, we used an Acantha- moeba co-cultivation method that we use routinely to isolate strains of the Parachlamydiaceae. This method has been shown to work for culture of S. negevensis (Kahane et al., 2001). In the present study, co-cultivation of disrupted Bemisia with amoebae in trypticase soy yeast broth did not result in chlamydial growth in the broth or amoebae. Each time we thought the endosymbiont might be growing, it was lost from the amoeba culture, perhaps due to extremely slow Published online ahead of print on 4 March 2005 as DOI 10.1099/ ijs.0.63454-0. The GenBank/EMBL/DDBJ accession numbers for genomic frag- ments containing the rRNA operons of ‘Candidatus F. bemisiae’ Falk and ‘Candidatus F. eriococci’ Elm are respectively AY140910 and AY140911. An extended neighbour-joining tree is available as supplementary material in IJSEM Online. 63454 G 2005 IUMS Printed in Great Britain 1581 International Journal of Systematic and Evolutionary Microbiology (2005), 55, 1581–1587 DOI 10.1099/ijs.0.63454-0