**5. Conclusions**

There is a major difference between microalgae and cyanobacteria in terms of their cell structure and this work has presented unmistakable evidence that microalgae have a nucleus and chloroplast, and their makeup includes their full identity in a two-stranded DNA. On the other hand, cyanobacteria are identified by one-stranded DNA and do not have a nucleus and neither a chloroplast. However, Microalgae and cyanobacteria do photosynthesize to produce their food.

It is seen from research as discussed in this chapter that value products aimed to meet pharmaceutical and food needs are obtainable by continuous availability of nutrients to the microalgae in the culture media. It is also seen that to accumulate lipid in the order of triglycerides for biodiesel production, microalgae must experience nutrients deficiency in the culture media at the stationary stage of growth.

The hydrodynamics of the microalgal culture broth depends on the choice of bioreactor for a particular cultivation activity and contributes to the algal growth factor.

The versatility of the microalgal biomass is expressed in the diversity of metabolites produced by manipulation of the growth factors in favor of the desired product. Also, the choice of the strain will drive towards the targeted product.

#### **Acknowledgements**

The authors appreciate the Institute for Water and Wastewater Technology (IWWT), Durban University of Technology, Durban for providing the platform for scientific investigations.
