With the premise that unique capabilities can be found in microorganisms facing extreme conditions, we focused our efforts on desert biological sand crusts (BSC), one of the harshest environments to support life. Recently, we have isolated a small green alga (named Chlorella ohadii), which does not conform to some of the basic fundamentals in microbial ecology and photosynthesis:
- Acquired ability to acclimate to extreme environments is usually accompanied by reduced performance under optimal conditions but C. ohadii does not obey this rule. In its natural habitat, C. ohadii is facing diurnal desiccation-hydration cycles, vast temperature amplitudes and extremely high illumination intensities, yet when grown under laboratory conditions it exhibits the fastest growth rates ever reported for an alga.
- After many years of research, some feel that we have elucidated the functioning of the photosynthetic machinery, and what sets the upper limit for algal growth. However, the unparalleled fast growth, very high photosynthetic rates and resistance to photodamage, suggest this may not be the case; C. ohadii is completely resistant to photoinhibition, and its productivity is unaffected by irradiances as high as twice full sun light.
- Survival of C. ohadii in the BSC depends on close association with filamentous cyanobacteria; a unique and novel mode of interspecies interaction contributing to its fitness to the harsh habitat.
We shall present detailed physiological analysis of the unique properties supporting this phenomenal growth and resistances, combined with insights from their genomic, transcriptomic and metabolomic characterization.
