Secondary carotenoids formation by the green alga Chlorococcum sp.

The effects of temperature, pH and oxygen level on secondary carotenoids (SC) accumulation in Chlorococcum sp. were investigated. The optimal temperature, pH and oxygen level for the yields of secondary carotenoids and astaxanthin were 35 degreesC, pH 8 and 10% (v/v), respectively. While the ratio (R) of products containing hydroxyl group (s) to those containing keto group (s) increased with the increase of temperature and pH, R value decreased with the level of oxygen. These results indicate that higher temperature and pH favor the introduction of hydroxyl group to the corresponding substrates, however, under high oxygen level keto group was relatively easy to be added compared to the addition of hydroxyl.