Abstract
Endospore formation under environmental stress conditions is a well-established phenomenon for members of bacterial phylum Firmicutes, among which the most well studied ones belong to genus Bacillus and Clostridium. So far known sizes of the spores are > 500 nm. Nano-forms of bacteria have been reported but the notion still remains controversial.
In this study we provide direct evidence of living nano-entities (termed here as ‘nano-spores’) formed by a bacterial species of genus Bacillus under prolonged stress, which are capable of escaping though standard sterile filtration procedure. We further demonstrate the transformation of the nano-spores to mature forms upon nutrient supply and again conversion of mature forms to nano-spores under salt-ethanol stress. Our study not only unfurls the ability of bacteria to rapidly get transformed into yet-unknown spore forms in order to survive under harsh environment, but also brings to light the existence of smallest possible form of life.