My blog is interfering with Valentine's day.....

On Monday, we performed an experiment that will test the theory that dessication resistant organisms are also gamma radiation resistant. All 78 strains were exposed to 0, 3, 6, and 16 kGY and will be kept in a desiccated environment (humidity <5%) for 42 days. One colony from each plate was diluted to 300 ul and then divided into 4 tubes. The 1st plate will receive no radiationThis will be our control plate. Also, one organism a control plate was made for each strain and will not be kept in a dessicated environment. The tubes are incubated for 42 days. Each strain was spotted on a plate and will be kept in a dessicated environment for 42 days.

Dessication resistant organisms are thought to be inherently radiation resistant because the same DNA repairs mechanisms are used to survive both. For example, dessication and radiation both cause double stranded DNA breaks. Therefore, an organism who is dessication resistant already has the required machinery to repair the DNA damage caused by radiation. Also, we counted plates from the unradiated soil samples streaked on 1/21/09.

Our group looked for suspect Modestobacter colonies (pink, cream, dark brown colonies). Also, the results of our plate counts are attached in the excel document. Our plate counts showed that organisms streaked on 1/10 PCA had the most cfu/gram. This might be because the 1/10 PCA has limited nutrients that the resemble the nutrients of the soil sample and hence meet the needs of the organism without overwhelming it. The PCA might contain too much nutrients, and the 1/100 PCA might be not be enough. The plate counts should what was expected. The colony forming units declined with each dilution. We selected 10 strains that had colonies that were suspect Modestobacter, and we restreaked them onto the media in which they grew best. The graph of Modestobacter suspects is in the excel document.

Another test that we are performing on the strains is to test for starch hydrolysis. We have not yet streaked all of our strains on the starch plates because we simply ran out of media.
Sean Michael reran our DNA on the gel with better results. All but 73 ran on the gel. Yay!!!!

On a light note, I’m having the best Valentine’s Day ever. Some of you may think this is cheesy, but my boyfriend is taking me around campus to each of the places on the “101 things to do before you leave LSU” list. At each place I have a rose. How exciting! The journey started today with lunch at the faculty club, a visit to the African American center, the internationcultural center, and the alumni place (la da cook something?).

Gobi-1 1/10 PCA -1 dilution: