Utilization of invasive algal biomass for bioethanol production and the dynamics of planktonic fungi in the West Pacific

Abstract

Algae represent the most promising feedstock for biomass derived biofuel production. Certain invasive algae in Hawaii can form dense biomass and are potential feedstocks for bioethanol production. In this study, the biomass from the invasive algae Gracilaria salicornia was used as feedstock for ethanol production using the ethanologenic strain Escherichia coli KO11. The algal hydrolysates were successfully utilized in a two-stage saccharification and fermentation platform, showing no inhibition of its bacterial fermenting ability, and producing 79.1 g ethanol from one kilogram of dry algal mass. Algae contain large quantities of species-dependent polysaccharides that cannot be readily metabolized by current ethanologenic bacteria. To fully explore the potential of microbial conversion of algal biomass and increase the systematic efficiency for ethanol production, culture-dependent and independent methods were applied to identify bacterial candidates fulfilling these purposes. The microbial communities profile associated with selected native and invasive algae were determined, which supplied valuable information in searching for candidates for polysaccharides utilization. Furthermore, microbes that can facilitate consolidated bioprocessing (CBP)--a process that can potentially optimize the systematic efficiency of biomass derived ethanol production--are isolated from various sources. Two bacteria FNP1 and TF2 showed great potential in further engineering for CBP platform development. Collectively, this study supplied valuable information in developing an efficient bioethanol production platform using invasive algal biomass. The dynamics of planktonic fungi in the west Pacific was investigated in part II of the dissertation. This study revealed that planktonic fungi are molecularly diverse and the fungal distribution was related to major phytoplankton taxa and various nutrients including nitrate, nitrite, orthophosphate and silicic acid. Over 400 fungal phylotypes were recovered and nearly half of them grouped into two major novel lineages. Ascomycota and Basidiomycota were found to be dominant groups at majority of the investigated stations. These results suggest that planktonic fungi are an integral component of the marine microbial community and should be included in future marine microbial ecosystem models.