HALOANAEROBIUM LACUSROSEUS SP-NOV, AN EXTREMELY HALOPHILIC FERMENTATIVE BACTERIUM FROM THE SEDIMENTS OF A HYPERSALINE LAKE

A new extremely halophilic chemoorganotrophic bacterium (strain H200(T ) [T = type strain]) was isolated from the hypersaline sediments of Re tba Lake in Senegal, This organism was a sluggishly motile, rod-shaped , non-spore forming, gram-negative, obligate anaerobe that grew optima lly at 40 degrees C in the presence of 180 to 200 g of NaCl per liter. The DNA base composition was 32 mol% guanine plus cytosine. The ferme ntation products from glucose were ethanol, acetate, H-2, and CO2. Yea st extract was required for growth. The fermentable substrates include d D-fructose, galactose, D-xylose, cellobiose, lactose, maltose, sucro se, starch, D-mannitol, glycerol, and Casamino Acids, On the basis of the results of a 16S rRNA sequence analysis, strain H200(T) was found to be related to Haloanaerobium species, The 16S rRNA sequence of stra in H200(T) differed from the sequences of the three previously describ ed Haloanaerobium species, and strain H200(T) also differed from these organisms in its NaCl range for growth (60 to 340 g/liter); strain H2 00(T) grew in the presence of the highest NaCl concentration recorded for any halophilic anaerobic organism, including the three previously described Haloanaerobium species, We propose that strain H200(T) (= DS M 10165) belongs to a new Haloanaerobium species, Haloanaerobium lacus roseus.