•Interactions between population biology and physiology: My former Ph.D. student John Delong made some valuable discoveries about the ecology and life history of single-celled eukaryotes. His research suggests that density has a major impact on the regulation of cell metabolism and cell division at all densities and that this is affected by growth temperature (DeLong and Hanson 2009a,b, 2011). While this is not surprising when comparing log-phase growth to stationary-phase, it is surprising to see between the lowest densities that we could measure. Population-level discoveries such as this and the desire for many biofuels companies to use open ponds raise obvious questions about competition between species and function of algal agro-ecosystems. We believe that developing a successful algal lipid production system in an agricultural context will require implementation of ecological principles at its core. Ecological theory suggests that diverse microbial communities may produce larger amounts of lipids than single-species systems while simultaneously reducing the need for expensive inputs.  In addition, diverse communities are more reliable producers and thus should have low maintenance costs.  This increased system stability is an especially important issue in lightly managed systems such as open or semi-open raceways.  In essence, the “ecosystem services” provided by a microbial community may do much of the work needed to optimize lipid production, while keeping maintenance costs low relative to a single-species system. 

•Interactions between CCMs and lipid composition: Many algae that have great potential for high lipid yield also have inducible CCMs. However, the relationship between CCM activity and lipid production has not been investigated, nor has the CCM activity been well assessed in most species of interest. The question is obvious: does the enhanced ability to capture CO2 by expressing a CCM outweigh the cost of maintaining the cellular CCM machinery with respect to lipid production? In addition, does this relationship depend on the density of the culture? I am gathering data on these two questions with my current funding from Sandia National Laboratories.