Molecular Basis for Detection and Cytotoxicity Caused by Cyanobacterial Producing Microcystin in Harmful Algal Blooms

Steve Mauro, Ph.D.Gannon University

mauro003@gannon.edu

Cyanobacteria are common in freshwater environments

- These are bacteria capable of undergoing photosynthesis

- They produce approximately 25% of the worlds oxygen

- In Presque Isle beach water, cyanobacteria compromise approximately 27% of bacterial

content

Bac-teroidetes

Cyanobac-teria

Pro-teobacte-

ria

Actinobacteria

Certain cyanobacterial strains can produce toxins

- These cyanobacterial types become more prevalent as the summer

progresses

INSERT PICTURE OF BLOOM HERE!!!

Toxin producing cyanobacterial genera include: - Microcystis- Plankothrix - Anabaena- Nodularia

- Many aggregate together in a bloom

- Temperature, nutrient content, and buoyancy are some factors involved in propagating harmful algal blooms

The toxin is produced due to the expression from a mcy gene cluster

There are many variants of this toxin that alter specific toxic impact

Toxin expression

Gene regulatory mechanisms are not clear but expression appears to be constitutively active in environmental samples

The microcystin toxin is transported into cells and acts by hyperphosphorylating proteins

Can lead to: - Nausea/vomiting - Intrahepatic bleeding- Cancer - Skin irritation- Acute respiratory pneumonia - Gastroenteritis

Toxin Etiology

WHO guidelines for concentration of microcystin exposure Water type Risk level Microcystin

concentrationCyanobacteria concentration

Drinking water High 1 ppb Not detected

Recreational water

Low 1-4 ppb < 5,000 cells/mL

Recreational water

Moderate 4-20 ppb 5,000-20,000 cells/mL

Recreational water

High >20 ppb 100,000 cells/mL

Concentrations found thus far in Presque Isle water samples using ELISA assay

0

1

2

3

4

5

6

7

Beach samples-no bloom Bay samples- no bloom Bay samples- bloom

Avg.

con

cent

ratio

n m

icro

cysti

n (p

pb)

Conclusions/future perspectives

Cyanobacteria is a common component of the Presque Isle ecosystem

Microcystin is consistently present in Presque Isle bathing waters in the absence of a bloom at what would be considered acceptable levels of exposure

Blooms have been detected in the Bay at levels that pose slight to moderate risk to humans

Ongoing research and monitoring efforts are needed to better understand the spatial and temporal factors that drive mcy gene expression and harmful algal bloom formation

Regional Science Consortium

Funding Sources