Abstract
Photosynthetic organisms have a wide variation. The primary symbionts such as chlorophytes and rhodophytes are organisms that cyanobacteria got into non-photosynthetic eukaryotes. The second symbionts such as heterokontphytes, haptophytes and dinohytes are that the primary symbionts got into non-photosynthetic eukaryotes. The second symbiotic algae are defined as the second symbiotic eukaryotes driving oxygen evolving photosynthesis. In this paper, I will introduce wide variation of carbon metabolism of the secondary symbiotic algae including a novel pathway of beta-carboxylation in the chloroplast of haptophytes. The second symbiotic algae are known as one of sources of biofuel and limestone production in ancient ara. Present species of those algae are producing a huge bloom in the ocean and transporting CO2 into the oceanic sediments and therefore their carbon fixation and metabolism play key function in the global environment. The important role and their potential of such algae in the global environmental issues also will be discussed.
