Please include the 4 pictures of our dilution series(-1, -2, -3, -4 of MA)
Gobi -1 dilution Marine Agar:
Gobi -2 dilution Marine Agar:
Gobi -3 dilution Marine Agar:
Friday, February 13, 2009
Summary of the Week.........
This past Monday, we started our desiccation experiment. We plated 10 um of each sample (that had undergone either 0, 3, 6, or 16 kGys of radiation) on the types of media they grow best on (either 1/10, 1/100, PCA or MA). We incubated these at 25•C. We then spotted 10um of each sample into wells to test for desiccation resistance. On Wednesday, we counted the colonies on our plates from 1/21 that did not undergo any radiation. We found that 1/10 PCA had the most bacterial colonies growing while PCA had the least. We then took pictures of dilution plates of MA (including -1, -2, -3, -4) in order to show that the higher the dilution factor, the lower the bacterial colony count will be. We also took pictures of -1 dilutions of MA, 1/10 PCA, 1/100 PCA, and PCA. We did this in order to show the changes in colony counts among the different medias. We selected 10 different colonies from the -1 and -2 MA and the -3 1/10 PCA that we thought might be Modestobacter and streaked them onto new plates (in order to isolate them). Lastly, we streaked a few of our strains onto media that contains starch to see if they would grow. We incubated these plates at 25•C.
Please include the 4 pictures of our dilution series(-1, -2, -3, -4 of MA)
Please include the 4 pictures of our dilution series(-1, -2, -3, -4 of MA)
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This is my (Lauren's) post. I didn't realize that we were supposed to write such an extensive summary--sorry! So, to clear some things up, the sample that we plated was Gobi soil. I wanted to include pictures of our dilution sample (MA -1,-2,-3,-4), which are on airset. This shows that there are fewer colonies on the more diluted plate, and the most colonies on the least diluted plate (which is probably obvious to everyone). As for plating samples on the starch---that is to test for amylase (which breaks down starch to glucose) production, right?
ReplyDeleteI just read Dr. Rainey's post and figured out that plating on the starch is to test for amylase production.
ReplyDeleteI love how I've now posted 3 comments on my own blog post. Discussion of soil counts from airset (our soil sample is Gobi, not Golbi, just to clarify):
ReplyDeleteIt is very obvious that our sample grew best on 1/10 PCA (average of 102 colonies) and the least on PCA (average of 26 colonies per plate). This seems strange since it seems that the bacteria would thrive with more nutrients available. Marine agar plates came in at a close second, with an average of 97 colonies per plate. This shows that our sample is very tolerable of/requires salt to live. 1/100 PCA came in third with 58 colonies per plate. All of these counts are taken from our -1 (least diluted) plates. On our more diluted plates, 1/10 continued to have the most colonies per plate. We had some on -4 and even a few on -6 (that could be from contamination, maybe, since we didnt have any growth on -5). In order to calculate cfu/mL, we multipled our average number of colonies times 10 (the inverse of the dilution) and then again by ten (to convert from microliter to milliliter). These results can also be found on the chart in airset.
on previous post: I meant to write cgu/g not cfu/mL. Also, referring back to my original post: when we restreaked colonies of suspected Modestobacter onto new plates, we chose the colonies based on color. From researching our organism, I have found that most colonies are a peachy-pink color, but can turn dark green-black if they do not have enough nutrients. Therefore, we chose mostly pink, peack, light orange colonies to restreak with. We searched for darkly colored colonies too, but most of them had fuzz growing on top of them (which could indicate contamination and is also not indicative of Modestobacter), so we decided not to isolate these. Hopefully we chose at least one colony that was actually Modestobacter.
ReplyDeleteon the volumes/units thing - you plated 10 ul (microliters) not um ?
ReplyDeleteChristy also sent me some tables reakted to the counts and isolates of her group - they are posted at AirSet
ReplyDeleteThe dilution series on MA pictures for the Gobi soil have now been added to thsi blog - better Sunday afternoon task than having to cut the grass :-)
ReplyDeletethank you for posting the pictures! yes, I meant 10 uL...careless error.
ReplyDeleteOMG Lauren you have to find a new name for your blog lol! Initially I thought it was Rainey's blog!
ReplyDelete