Tolerance of the cell layer of Nostoc sp. HK-01 against UV radiation

Cyanobacteria have several abilities to qualify as candidate organisms that can grow in extreme environments, such as on Mars. Dry colonies of a cyanobacterium, Nostoc sp. HK-01, can tolerate several elements of space environments. It has been reported that cyanobacteria have the ability to produce extra-cellular substances (ES), which are protective against UV radiation. The intra-cellular substances may have the same abilities as ES. We investigated the correlation between the protective abilities of ES and intra-cellular substances against UV radiation and the cell layer. Here, we show the relationship between the thickness of the cell layer and the tolerance against UV radiation in Nostoc sp. HK-01. Detailed information about the relationship between cell layer thickness and tolerance against UV radiation would contribute to calculating the number of cells which need to be transported to extraterrestrial environments for space agriculture.