Natronococcus amylolyticus sp. nov., a haloalkaliphilic archaeon.

The alpha-amylase-producing haloalkaliphilic archaeon Natronococcus sp. strain Ah-36T (T = type strain) was isolated previously from a Kenyan soda lake, Lake Magadi. Most cells of strain Ah-36T occurred in irregular clusters, and the colonies were orange-red. The polar lipids of this organism were composed of C20, C20 and C20, C25 derivatives of phosphatidylglycerol and phosphatidylglycerophosphate. Phosphatidylglycero-(cyclo-) phosphate, which is characteristic of Natronococcus occultus, was not detected. The complete nucleotide sequence of the 16S rRNA gene revealed that the closest relative of strain Ah-36T is N. occultus ATCC43101T (level of similarity, 96.4%), an extremely halophilic archaeon. However, strain Ah-36T did not exhibit a significant level of DNA homology to N. occultus ATCC43101T, which represents the only previously described species in the genus Natronococcus. We describe a new species for strain Ah-36T, for which we propose the name Natronococcus amylolyticus.