This week was interesting..................

On Monday we had a guest teacher who discussed desiccation and radiation. Manish, our guest teacher, thoroughly discussed the desiccation process which is exposing the organism to low humidity and giving it radiation. Radiation and desiccation causes damage to the organisms DNA and oxidative damage. In desiccation the damage on the cell is due to the breaking of the double strand from exposure to radiation and little or no water. As a combat to this, the cell produces glycan or trehalose. Some bacteria that can survive environments of radiation are Deinococcus radiodurans, Kocruia, Trupera radiovitrix, Rubrobacter, and Methylobacterium.

For our experiment we started the desiccation process, which is 42 days and the radiation process which takes place at 3, 6, and 16 kilograde. Through this we will see which organisms are more resistant to radiation and which are not. Those that survive 3 and 6 kilograde are least moderate resistant. In total we will have 4 sets or tubes: one control, a 3 kilograde set, a 6 kilograde set, and a 16 kilograde set. On Monday we only performed the experiment at the control, 3, and 6 kilogrades. The 16 kilograde desiccation was performed on Wednesday. On Wednesday we performed a number of task which included: counting the unradiated plates from the first day, performing radiation for 16 kilograde plates, streaking cultures on media that contains starch, performing dilution calculations, and checking for pink colonies from our original plates. We started the day off by performing our radiation experiment at 16 kilogrades. This was fairly straight forward and identical to those task performed on Monday.

Next, from our original plates we streaked the strains on the media of which it grew best on, which also contained starch.

After, we counted the colonies on our plates form the Little Red Hill. There are many trends which can be found from the number of colonies on each plate. The plates of marine agar decreased greatly from dilutions of -1 through -6. This show two things: some organisms found here are salt tolerant and grow best in envrioments which contains salt. Even at a dilution of -6 there were 6 countable colonies on the marine agar plate. This shows that some organisms found in this area can tolerate environments which contain salt. Also, as dilution increased from -1 to -6 the number of colonies present decreased. This could be because these organisms need environments which contain salt. In addition from these plates I inferred that Streptomyces are salt tolerant. This is due to the fact that these white fuzzy colonies were present on this salt media.

Below is a picture of -2 diluted MA plates and -4 diluted MA plates. It is apparent that those environments (plate) with a greater concentration of salt had more growth. However, there were colonies present at greater dilutions, such as -4.

LRH-1 -2 dilution on MA:

LRH-1 -4 dilution on MA: