Real-time Spectroscopic Analysis of Microalgal Adaptation to Changing Environmental Conditions

Increases in anthropogenic pollution are causing many environmental problems; understanding their impact on the environment has become an important issue. Industrialization and the burning of fossil fuels have caused increased levels of carbon dioxide to enter the atmosphere, which is contributing to global warming and ocean acidification. Agricultural runoff has caused levels of inorganic nitrogen and phosphorus to rise, where they have been noted to cause harmful algal blooms. Marine ecosystems have been particularly affected as both of these forms of pollution accumulate in bodies of water. Microalgae are important organisms in these ecosystems because they sequester these pollutants and convert them into biomass. Because the chemical composition of microalgae’s biomass depends on the nutrient availability in their environment, further use of microalgae as an in situ indicator of environmental conditions is investigated.

The objective of this thesis is to determine how microalgae samples respond in real time to changes in the nutrient availability of their environment. To accomplish this, a novel sensing technique was developed that allowed spectroscopic analysis of live microalgae samples. FTIR spectroscopy in ATR mode was used to repeatedly monitor cells at two distinct carbon dioxide concentrations, standard and elevated, over a twelve hour time period. The change in absorbance over time was modeled nonlinearly to gain information about how the chemical composition of microalgae adapted to higher levels of carbon dioxide. This innovative hard-modeling of changing spectroscopic time series demonstrated the ability to yield interpretable chemical information about the adaptation of microalgae to an altered environment.