CONCLUSION

Growth of many species of diatoms is limited by the availability of nitrogen and salinity (Lapointe 1989, Russ and McCook 1999). Lipid act as a secondary metabolite for diatoms, and stress or unfavourable condition such as nutrients, growth phase, temperature, light, etc., leads to the production of more lipids in diatoms (Hu et al., 2008). In the present study, maximum total lipid was observed during growth phase in WCg media containing sodium nitrate as a nitrogen source which is also the original source of nitrogen in the media for Nitzschia sp. Even though high lipid yield was found in urea source, it accounted for low cell density, which makes it less promising.