The desert green algae Chlorella ohadii thrives at excessive high light intensities by exceptionally enhancing the mechanisms that protect photosynthesis from photoinhibition

Although light is the driving force of photosynthesis, excessive light can be harmful. One of the main processes that limits photosynthesis is photoinhibition (PI), the process of light-induced photo-damage. When the absorbed light exceeds the amount that is dissipated by photosynthetic electron flow and other processes, damaging radicals are formed that mostly inactivate photosystem II (PSII). Damaged PSII must be replaced by a newly repaired complex in order to preserve full photosynthetic activity. Chlorella ohadii is a green micro-alga, isolated from biological soil crusts in the desert that thrive under extreme high light and is highly resistant to PI. Therefore, C. ohadii is an ideal candidate for study the molecular protection mechanisms from PI. To charac-terize these protection mechanisms in C. ohadii, we compared thylakoids of cells that were grown under low light versus extreme high light intensities. C. ohadii were found to employ all three known PI protection mechanisms: i) performance of massive reduction of the PSII antenna size; ii) accumulate protective carotenoids; and iii) possess a very fast repair cycle of photo-damaged reaction center proteins. This work elucidated the molecular mechanisms of photoinhibition resistance in one of the most light-tolerant photosynthetic organisms and shows how photoinhibition protection mechanisms evolved to marginal conditions enabling photosynthesis-dependent life in severe habitats.One Sentence HighlightAnalysis of the photosynthetic properties of a desert algae that thrives at extreme high light in-tensities reveals how protection from photoinhibition is achieved by a remarkable enhancement of three protection mechanisms.

Biodiesel production and Environmental CO2 cleanup using Oleaginous Microorganisms from Al-Hassa area in Saudi Arabia

Biodiesel production is rapidly moving towards the mainstream as an alternative source of energy. Algae oil is one of the viable feed stocks among others to produce Biodiesel. However the difficulties in efficient biodiesel production from algae lie not in the extraction of the oil, but in finding an algal strain with a high lipid content and fast growth rate. This paper presents an experimental work performed to study the production of biodiesel from local algae strains in Al-Hassa territory of the eastern province in Saudi Arabia which was found to contain high lipid contents and show rapid growth. The collected results predict that those types of desert algae are promising and are considered to be a potential feedstock for biofuels.