The machine employs a light meter to detect the light by-product of the bacteria's
cellular respiration. A decrease in cellular luminescence is an indicator to
decreased respiration in the bacteria; therefore, this result is indicative
to an increase in sample toxicity (i.e. the more toxic the sample the greater
the percent light loss). I filter water samples for coliform bacteria, specifically for the identification and differentiation of Escherichia coli (E. coli).
We use a simple filtration method for a MPN, most probable number, of colonies
per 10 ml. Thus, 10 ml of a sample is combined with 50 ml of filter seawater
and suctioned through a clean filter using a hand held vacuum device. The filter
paper is them placed on an agar media which contains chromogens specific to
E. coli and other general coliforms. In the lab this allows us to distinguish
between the E. coli, a blue colony, or other general coliforms, a red colony.
In between filtrations a methanol wash is used to clean the filtration equipment.
Steve filters water samples for chlorophyll a and photosynthetic pigments.
The
chloropyll-a analysis is performed on site by the Crary Analytical Laboratory
Group while the pigment samples are stored a -20 degrees Centigrade and shipped
back to the GERG laboratory in College Station, Texas for subsequent analysis.
At the end of the evening, generally ending between 8:30pm and 10pm, Sally and I like to celebrate with a "Miner's Dance" or an "Irish Jig".
It's
lends a nice touch to the ending of the day, a celebration of a job well done.
D.
Alsup (Gielstra)