Subcommunity FTIR-spectroscopy to determine physiological cell states.

Estimation of growth potential in a complex community is a great challenge in biotechnical processes and environmental water quality control. Recently it has been shown that the macromolecular structure is a good indicator for the growth potential of phytoplankton cells. A functional understanding of natural phytoplankton communities requires a community analysis by means of single particles technologies. However, conventional biochemical methods are not sensitive enough to determine the macromolecular composition of a single cell or cell aggregates. This problem can be resolved by Fourier transform infrared (FTIR) spectroscopy, which delivers results similar to biochemical analysis with a much smaller sample size. The combined approach of flow cytometric analysis with subcommunity sorting and subsequent FTIR-analysis offers new perspectives for the understanding of community functioning and process optimization.