Download the Algal Biofuels Roadmap draft document - Sandia

1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
The ideal screen would cover three major areas: growth physiology, metabolite
production, and strain robustness. The term ―growth physiology‖ encompasses a number
of parameters such as maximum specific growth rate, maximum cell density, tolerance to
environmental variables (temperature, pH, salinity, oxygen levels, CO2 levels), and
variability of in situ versus laboratory performance. Because all these parameters require
significant experimental effort, it would be very helpful to develop automated systems
that would provide information regarding all parameters simultaneously. Screening for
metabolite production has to include not only the metabolite composition and content, but
also the productivity of cells regarding metabolites useful for biofuels generation. Rapid
oil analyses of strains could greatly facilitate this work. An ideal analytical method would
allow for distinction between neutral and polar lipids, and would also provide fatty acid
profiles.
At this time, bottleneck for screening large numbers of microalgae stems from a lack of
high-throughput methodologies that would allow simultaneous screening for multiple
phenotypes, such as growth rates and metabolite productivities. In terms of biofuel
production, it would be beneficial to be able to screen in high throughput fashion for lipid
content.
To improve the economics of algal biofuel production, other valuable co-products must
be generated; this would require determining cellular composition regarding proteins,
lipids, and carbohydrates. Further, many strains also excrete metabolites into the growth
medium. These have been largely ignored, but they might prove to be valuable coproducts,
at least in systems that do not suffer from contamination. New approaches are
necessary to develop screening methods for extracellular materials.
For mass culture of a given algal strain, it is also important to consider the strains
robustness, which includes parameters such as culture consistency, resilience, community
stability, and susceptibility to predators present in a given environment. Previous studies
revealed that microalgae strains tested in the laboratory do not necessarily perform
similarly in outdoor mass cultures (Sheehan et al., 1998). To determine a strain‘s
robustness, small-scale simulations of mass culture conditions will need to be performed.
The development of small-scale but high-throughput screening technologies will be
essential to enable testing of hundreds to thousands of different algal isolates.
Development of Novel Concepts and Approaches for Strain Screening
Solvent extraction is the most common method for determination of lipid content in algal
biomass, and it requires both a significant quantity of biomass and effort. Fluorescent
methods using lipid soluble dyes have also been described, and though these methods
require much less biomass (as little as a single cell), it has not yet been established if
these methods are valid across a wide range of algal strains. Further improvements in
analytical methodology could be made through the development of solid-state screening
methods.
Development of Strain Databases
19