S51 - Microspectroscopy measurements on single strands of the Cyanobacteria Microseira wollei

In fifteen words or less, explain the significance of this contribution (Novel Aspect).: Microscope capable of of taking fluorescence and transmission spectra in tandem.

Abstract Text:

Microseira wollei (M.wollei) previously known as Plectonema wollei and Lyngbya wollei is freshwater filamentous cyanobacteria. The organism forms long filaments, typically 25-60 μm wide, in which cells are stacked tightly together and resemble plates. M. wollei often forms benthic mats on the bottom of the water column but can become easily dislodged and float to the top of the water column. It produces several saxitoxins and Lyngby Wollei  toxins (LWT1-6) that can cause paralytic shellfish poisoning in humans and other mammals. Microseira wollei is a cyanobacterium that persists in ecosystems year after year, making it difficult to eradicate. Blooms have consistently grown across the United States throughout the past decade; one such bloom is in Lake Wateree, South Carolina.

M.wollei exhibits fluorescence from chlorophyll a and phycobilin proteins. However, M.wollei also has other pigments such as photoprotective carotenoids that do not transfer energy to the photosystem, thus absorption measurements in tandem with fluorescence spectroscopy are needed to study the optical properties and pigmentation of M.wollei. Our laboratory has designed a single cell fluorescence excitation microscope in tandem with an absorption channel to allow for the study of both photosynthetic and photoprotective pigments inside a singular cell. In this experiment the instrument was used to look at how the pigment makeup and concentration changes between cells in different locations therefore different ages in strands of Microseira wollei. The sample was excited with wavelengths from 450-650nm with an excitation spot size of 20 μm. In this poster we will show spectra and images revealing how pigment concentration and light scattering vary with cell history.