Two novel yellow pigments natronochrome and chloronatronochrome from the natrono(alkali)philic sulfur-oxidizing bacterium Thialkalivibrio versutus strain ALJ 15 Shinichi Takaichi, a, * Takashi Maoka, b Naoshige Akimoto, c Dimitry Yu. Sorokin, d,e Horia Banciu e,  and J. Gijs Kuenen e a Biological Laboratory, Nippon Medical School, Kosugi, Nakahara, Kawasaki 211-0063, Japan b Research Institute for Production Development, Shimogamo-morimoto-cho, Sakyo, Kyoto 606-0805, Japan c Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida-shimoadachi-cho, Sakyo, Kyoto 606-8501, Japan d Institute of Microbiology, Russian Academy of Science, Prospect 60-let Octyabrya 7/2, 117811 Moscow, Russia e Department of Environmental Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands Received 4 August 2004; revised 8 September 2004; accepted 10 September 2004 Available online 25 September 2004 Abstract—Two novel membrane-bound yellow pigments natronochrome (1) and chloronatronochrome (2) were isolated from the obligately chemolithoautotrophic sulfur-oxidizing natrono(alkali)philic bacterium Thialkalivibrio versutus strain ALJ 15. They were derivatives of fully unsaturated fatty acids with a phenyl group, and their structures were determined by spectral data. Ó 2004 Elsevier Ltd. All rights reserved. Soda lakes represent unique saline habitat with extreme- ly high pH and alkalinity due to the presence of high concentration of sodium carbonate. Despite this, fully structured and diverse prokaryotic communities develop even in hypersaline soda brines. 1,2 Recently, a new branch of obligately chemolithoautotrophic sulfur- oxidizing bacteria has been discovered in soda lakes, which includes three new genera in the Gamma- proteobacteria: Thialkalimicrobium, Thialkalivibrio, and Thioalkalispira. 3,4 All of them belong to obligate haloal- kaliphiles, which mean absence of growth at neutral pH and optimum growth in saline media with pH around 10. Since most of the isolates preferred the sodium carbonate salts over the sodium chloride, they should be called natrono(alkali)philes in contrast to (halo)alkaliphiles. The aerobic chemolithoautotrophic sulfur bacteria usually referred to as ÔcolorlessÕ in con- trast to the anaerobic purple sulfur bacteria. However, all the extremely salt-tolerant Thialkalibibrio strains (about 50) isolated from the hypersaline soda lakes pro- duce yellow pigments. The low-salt-tolerant Thialkaliv- ibrio and Thioalkalispira strains do not produce any pigments. 3,4 The pigments were found to be associated with the membrane fraction of the cells in these novel bacteria. This letter reports the isolation and structural elucidation of two novel yellow pigments from Thialka- limicrobium versutus strain ALJ 15. High-density cultivation of T. versutus strain ALJ 15 was performed in 15 L fermentor with pH and dissolved oxygen control at air overpressure of 0.5–0.8 atm and 10–12 L of culture. The medium contained (gL À1 ): Na 2 CO 3 –95; NaHCO 3 –15; NaCl–16; K 2 HPO 4 –1; KNO 3 –1, pH 10.1. After sterilization, 0.5 mM MgCl 2 Æ 6H 2 O, 1 mL/L of trace metal solution and 200 mM so- dium thiosulfate were added to the mineral base. The cells were harvested by centrifugation and lyophilized. The lyophilized cells (ca. 300 g) were air shipped to Japan, and then rehydrated. Pigments were extracted with MeOH. The extract was partitioned with CHCl 3 and water, and then CHCl 3 layer was evaporated. The pigments were subjected to column chromatography on DEAE-Toyopearl 650M, and eluted with hexane/ acetone (1:1). The fraction was further purified by 0040-4039/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.tetlet.2004.09.073 Keywords: Pigment; Yellow pigment; Aryl-polyene ester; Chloro- natronochrome; Natronochrome; Thialkalibibrio versutus; Soda lake. * Corresponding author. Tel.: +81 44 733 3584; fax: +81 44 722 1231; e-mail: takaichi@nms.ac.jp   Present address: Department of Animal Physiology, Faculty of Biology, Babes-Bolyai University, 400006 Cluj-Napoca, Romania. Tetrahedron Letters 45 (2004) 8303–8305 Tetrahedron Letters