# BISC209/S11: Assignment 209 BIOLOG

Wellesley College-BISC 209 Microbiology -Spring 2011

## Assignment: Community Physiological Profiling of a Soil Community by Carbon Source Utilization

What to do with the DATA you have collected (A590nm) from your BIOLOG™ plate?

Calculating Average Metabolic Response (AMR) and Community Metabolic Diversity (CMD)
The calculation of AMR provides a method to compare total metabolic activity among soil communities or among aerobic or facultative microbes. The following calculations were built into the Excel template workbook: CALCULATING AMR: Average Metabolic Response over time and between soil sites and Average Carbon Source Utilization Ccore by the microbial community

Average Metabolic Response(AMR)= Σ(mean A590nm of triplicate carbon source tests - Mean A590nm of the three control wells) and less a threshold absorbance of 0.25nm / 31 (the number of carbon sources tested)

A high score indicates that there were many useable carbon sources for the community, a low score indicates that few of the carbon sources were able to be metabolized well. The template will calculate AMR for every date read. On the next to the last page of the template workbook, please fill in the AMR table by day.

CALCULATING CMD: community metabolic diversity. CMD is a simple way to represent the total number of substrates able to be effectively metabolized by the microbial community. It's a measure of diversity in use of carbon sources. CMD is calculated by summing the number of positive responses (wells with a positive A590nm value after all the corrections) at each incubation time. Any negative values are considered 0 absorbance.

On your worksheet enter either a 0 or a 1. Zero indicates that there was a negative value or 0 for corrected A590nm. A 1 indicates a positive value of greater than zero. Once you have entered a 1 or a 0 as the "corrected" absorbance for all the cells, the template will calculate the CMD for that day. Complete the final CMD table on the next to the last page of the template workbook.

GRAPHING THE DATA:

Please make figures from your data showing AMR, CMD, and Carbon Utilization patterns.

To graph AMR: You will plot your soil sample's AMR values on the y axis against time on the x to provide a quick comparison of metabolic response.

To graph CMD: Plot the calculated soil sample's CMD values on the y axis versus time on the x to get a sense of community functional metabolic richness.

Showing Carbon source utilization patterning:
Because neither AMR nor CMD analysis provides information about the pattern of carbon substrates used in each soil community, you must think about a different way to display these complex data. You could plot on the y axis the A590nmabsorbance on the final day or on what appears to be the peak day of data collection versus the 31 different carbon sources on the x axis. Note that there is no such thing as negative absorbance; therefore, any negative values should be graphed as zero. Are there better ways to organize and display these data to make your main point. What is you main conclusion about diversity of microbial metabolism in your soil community? How can you show that most effectively?