Temperature Optimum for Biomass Production of two Species of Benthic Diatoms

Abstract: Diatoms and other algae can be cultivated and beneficially used in several sectors with applications ranging from nutrient recycling to production of high-valued biomaterials used by the green energy industries, in pharmaceutical products or as food supplements. In this experimental study, the temperature optimum for biomass production was tested for two species of benthic diatoms, Diatoma sp. and Nitzschia sp., by measuring and relatively comparing parameters for biomass production and productivity between cultures grown at three different temperatures (13°C, 19°C, and 27°C). The parameters used as estimation for biomass and productivity to enable the comparison between the different treatments were cell density, concentrations of photosynthetic pigments, nutrient reduction, and growth rate. Photosynthetic activity was also measured to compare the influence of the different temperatures on the cell cultures and to enable for continuous supervision during the 16 days of the experiment. The Nitzschia sp. yielded insufficient result, however, the Diatoma sp. was clearly found to grow in all temperatures tested, but with the results suggesting its temperature optimum range to include at least 13°C to 19°C, and its upper limit to be between 19°C and 27°C. Interestingly though, the results also indicate that the temperature optimum may vary depending on the intended use. Cultivating Diatoma sp. for its biomaterials, such as silica frustules or highvalued substances like for instance fucoxanthin, would not be recommended in temperatures above 19°C based on these results, although, if cultivated primarily for nutrient recycling, temperatures of up to at least 27°C seem to work just as well as temperatures of 13°C to 19°C.