Isolation and Characterization of a Drought-Tolerant Cyanobacterium, Nostoc sp. HK-01

A cyanobacterial strain was isolated from cyanobacterial crusts taken from soil in Hyogo Prefecture, Japan and identified as a Nostoc species. This Nostoc strain is drought-tolerant, and its cells differentiated into a particular type, hormogonia, under dark and nutrient-poor conditions. The strain grows well in a liquid medium with a simple nutrient composition that was originally developed for the cultivation of symbiotic Nostoc. The maximum growth rate was attained at pH 8. The DNA sequences of the 16S rRNA region and trnL(UAA)-intron region were determined to classify this Nostoc species. The trnL(UAA)-intron sequence was homologous to a symbiotic Nostoc, and also to some extent to Anabaena sp. PCC 7120. This cyanobacterium, named Nostoc sp. HK-01, is promising as an improver of arid and nutrient-poor soils.