Abstract
Diatoms (Bacillariophyceae) are considered to be the most diverse class of algae, including as many as 250 genera and having possibly as many as 200,000 species. Because of their complex evolutionary history, they are referred to as having a mix-and-match genome with contributions from various sources, including red and green algae, bacteria and viruses. Diatoms are a ubiquitous class of algae that can virtually be found in every environment as long as water and sunlight are available. The capability to exploit and thrive in a wide range of habitats and ecological niches may be an explanation for the large differentiation observed at genome-scale levels within and between species. High gene redundancy and the capacity to activate fast responses to environmental triggers make diatoms highly successful, especially in environments characterized by high nutrient supply and abrupt fluctuations in light. In this chapter, we summarize the available genomes, discuss some photosynthesis-related features characteristic of diatoms and outline key features of photosynthetic regulation in terms of light quality and quantity. We also present an overview of diatom knockout mutants produced using novel genetic engineering techniques and discuss some attempts to employ these techniques to perform strain optimization for future commercial exploitation of diatoms.