Olivibacter sitiensis gen. nov., sp. nov., isolated from alkaline olive-oil mill wastes in the region of Sitia, Crete Spyridon Ntougias, 1 Constantinos Fasseas 2 and Georgios I. Zervakis 1 Correspondence Georgios I. Zervakis zervakis@kal.forthnet.gr 1 National Agricultural Research Foundation, Institute of Kalamata, Lakonikis 87, 24100 Kalamata, Greece 2 Agricultural University of Athens, Department of Agricultural Biotechnology, Electron Microscopy Laboratory, Iera Odos 75, 11855 Athens, Greece A novel, Gram-negative, non-motile, non-sporulating, rod-shaped bacterium isolated from a viscous two-phase olive-oil mill waste (‘alpeorujo’) is described. The strain, designated AW-6 T , is an obligate aerobe, forming irregular, pigmented creamy white colonies. The pH and temperature ranges for growth were pH 5–8 and 5–45 6C, with optimal pH and temperature for growth of pH 6–7 and 28–32 6C, respectively. Strain AW-6 T was chemo-organotrophic and utilized mostly D(+)-glucose, protocatechuate and D(+)-xylose, followed by L-cysteine, D(”)-fructose, D(+)-galactose, L-histidine, lactose, sorbitol and sucrose. Menaquinone-7 was detected in the respiratory chain of strain AW-6 T . The major fatty acids of strain AW-6 T were C 16 : 1 v7c and/or iso-C 15 : 0 2-OH, iso-C 15 : 0 , iso-C 17 : 0 3-OH and C 16 : 0 . The closest phylogenetic relative of strain AW-6 T was clone BIti35 (89.7 % 16S rRNA gene sequence similarity), while Sphingobacterium thalpophilum DSM 11723 T was the closest recognized relative within the Sphingobacteriaceae (88.2 % similarity). Strain AW-6 T showed a low level of DNA–DNA relatedness to S. thalpophilum DSM 11723 T (33.8–37.0 %). The DNA G+C content of strain AW-6 T was 45.6 mol%. Physiological and chemotaxonomic data further confirmed the distinctiveness of strain AW-6 T from members of the genera Sphingobacterium and Pedobacter. Thus, strain AW-6 T is considered to represent a novel species of a new genus within the family Sphingobacteriaceae, for which the name Olivibacter sitiensis gen. nov., sp. nov. is proposed. The type strain is AW-6 T (=DSM 17696 T =CECT 7133 T ). At the time of writing, the family Sphingobacteriaceae consists of the genera Sphingobacterium and Pedobacter (Steyn et al., 1998). The genus Sphingobacterium includes the following recognized species: Sphingobacterium antarc- ticum (the corrected name of S. antarcticus), S. faecium, S. multivorum, S. spiritivorum and S. thalpophilum (Yabuuchi et al., 1983; Shivaji et al., 1992; Takeuchi & Yokota, 1992). Steyn et al. (1998) erected the genus Pedobacter initially to accommodate the species Pedobacter africanus, P. hepar- inus, P. piscium and P. saltans; seven further species, Pedobacter caeni, P. cryoconitis, P. himalayensis, P. sandara- kinus, P. aquatilis, P. ginsengisoli and P. roseus have since been added (Margesin et al., 2003; Shivaji et al., 2005; Vanparys et al., 2005; Gallego et al., 2006; Hwang et al., 2006; Ten et al., 2006; Yoon et al., 2006). Only a few bacteria isolated from olive-processing products and residues have been recognized (Chamkha et al., 2001; Koussemon et al., 2001). Alkalibacterium (Ntougias & Russell, 2001) and Sporobacterium (Mechichi et al., 1999) are the only currently recognized genera; their type species, Alkalibacterium olivapovliticus and Sporobacterium olear- ium, were isolated from edible-olive wash-water and from an olive mill wastewater treatment digester, respectively. Alpeorujo is a liquid–solid waste produced by two-phase olive-oil decanters which is usually amended (before disposal) by Ca(OH) 2 to generate a moderately alkaline secondary waste (alkaline alpeorujo). To date, the only bacterial isolates recovered from alkaline alpeorujo have been either halotolerant alkaliphilic or halotolerant/alkali- tolerant micro-organisms (Ntougias et al., 2006). Here, we describe the morphological, physiological, chemo- taxonomic and phylogenetic characteristics of a novel, Abbreviation: ECL, equivalent chain-length. The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain AW-6 T is DQ421387. An electron micrograph showing the cell morphology of strain AW-6 T and a dendrogram based on data for 40 physiological and chemotaxonomic characteristics of strain AW-6 T , members of the genera Sphingobacterium and Pedobacter and Flavobacterium mizutaii are available as supplementary material in IJSEM Online. 398 64561 G 2007 IUMS Printed in Great Britain International Journal of Systematic and Evolutionary Microbiology (2007), 57, 398–404 DOI 10.1099/ijs.0.64561-0