Consequences of Drought Stress on Biofuels
(Phys.Org/U.S. Department of Energy) …However, weather conditions could greatly affect crop yields. In this study, researchers examined the effect of weather on biofuel production by comparing switchgrass and corn stover harvested after a year of major drought and after 2 years of normal precipitation. They found that the plants produced more sugar, but the sugar changed during pretreatment and produced toxic compounds rather than the desired fuels.
In response to the 2012 severe Midwestern drought, soluble sugar accumulated in switchgrass at significantly higher levels in comparison to non-drought years. The sugars were chemically changed during the pretreatment stage, the step that opens up the physical structure of the plant cell wall. The soluble sugars chemically changed by reacting with the ammonia-based pretreatment chemicals to form highly toxic compounds known as imidazoles and pyrazines. The formation of toxic compounds during the pretreatment stage inhibited conversion, the final step where intermediates such as sugars are fermented into biofuel by microorganisms, such as the microbe S. cerevisiae.
However, it may be possible to overcome this issue by 1) removing the soluble sugars before pretreatment or 2) using microbial strains resistant to the toxic effects of imidazoles and pyrazines. READ MORE Abstract (Biotechnology for Biofuels)