NATRONIELLA ACETIGENA GEN-NOV SP-NOV, AN EXTREMELY HALOALKALIPHILIC, HOMOACETIC BACTERIUM - A NEW MEMBER OF HALOANAEROBIALES

A new extremely haloalkaliphilic, chemoorganotrophic, homoacetogenic b acterium strain Z-7937(T)(T-type strain) was isolated from the bottom mud of the soda-depositing Lake Magadi, Kenya. It is an obligately ana erobic, motile, Gram-negative, spore-forming rod growing in the pH ran ge pH 8.1 to 10.7 and optimally in the range pH 9.7 to 10.0 under cond itions of high alkalinity caused by saturation with trona. It has an o bligate requirement for sodium carbonate and chloride ions. The optimu m salt concentration for growth is in the range 12-15% wt/vol, and gro wth occurs within the range from 10% to 26%. Strain 2-7937(T) is a mes ophile with an optimal temperature for growth of 37 degrees C, and a m aximum of 42 degrees C. The G + C content of strain Z-7937(T) is 31.9 mol%. A limited number of compounds are utilized, including lactate, e thanol, pyruvate, glutamate, and propanol. Acetate is the main end pro duct. 16S rDNA sequence analysis shows strain Z-7937(T) to be a member of the order Haloanaerobiales and to represent a new branch within th e family Halobacteroidaceae. On the basis of its novel physiology and phylogenetic position, we propose strain Z-7937 as a new species of a new genus, Natroniella acetigena gen. nov. sp. nov. The type strain is Z-7937(T) (= DSM 9952).