Fun with Soil – Elizabeth

Where did you obtain your soil sample?

I got my soil from the path that walks up the right side of the football field behind Alumni Gym. The exact coordinates are Lat 42.816563, Long -73.926441. There was a layer of mulch on top that I moved out of the way and then I dug down about two inches. The soil was moist, but not wet, and dark. There were more ants in the soil than I expected once I got down into it.

Why did you choose this location?

I chose this location because I feel like it hasn’t been disturbed in a while. Most of the bushes in this area are just tended by facilities; not really replanted each year. The soil and the bacteria in it have probably been sitting long enough to have seen competition and (hopefully) some antibiotic production.

Do you expect a lot of isolates? Why or why not?

I expected the least-diluted plates to be covered, so I guess that’s one way to quantify “a lot of isolates.” However, given that its a soil sample and it was under a layer of mulch with at least some exposure to water, there’s probably a fair amount of anaerobic organisms there that we won’t grow at all, so I would expect very few of those isolates.

Have you initial observations supported this?

Yes – when I saw the plates, the ones with 1/100 dilutions were covered. They also looked like the serial dilutions were somewhat successful, as the numbers of colonies on each one decreased (based on rough estimate – I didn’t count them).

What media did you choose? What dilutions?

I chose to work with LB, 10% TSA, and R2A using dilutions of 1/100, 1/1000, and 1/10000. I used the LB as standard and then chose the 10% TSA as a “medium richness” media and the R2A as a bit of a less nutritious media. I thought this range of nutritional value would provide good comparison between plates. My dilution choices were based on our protocol from the test plates (the first lab); we weren’t seeing countable plates until the 1/10000 dilutions, so I made sure to get a 1/10000 plate for each media.

Will you need to redo any?

None of them initially seemed like they needed to be redone. They all had some growth on them and the lowest dilutions seemed countable.

How did your sample differ on the different media?

Honestly, I didn’t look at them too much. For personal reasons, my time in the lab has been limited and I haven’t been able to compare them in detail.

Fun with Soil – Tommy

Where did you obtain your soil sample?

My soil sample was collected under a tree on the North side of the Rugby field at Union. I dug down underneath a layer of mulch to reach the soil, which was held together by lots of roots. It was a dark, damp soil and contained wood chips from the relatively fresh mulch above.

 

Why did you choose this location?

Before inauguration, I saw groundskeepers putting fresh mulch around the trees and bushes around campus. I figured these frequently cared for soils might contain diverse microbe populations because of the recent layers of material deposited upon them. Part of the reason I was attracted to this soil was because its dark color reminded me of topsoil which I think of as being fertile with rich microbial life.

 

Do you expect a lot of isolates? Why or why not?

Hopefully some. It is encouraging that Penicillin-resembling molds grew on my PDA plates because if this antibiotic producing fungus lives in the soil, then possibly microbes that produce antibiotics will be selected for. The dark colour of the soil leaves me hoping for diverse microbial life some of which could be antibiotic producing. However, the fact that it was damp implies that some anaerobic microbes most likely were present, and I don’t expect these will grow on the plates much.  

 

Have you initial observations supported this?

Yes, lots of diverse colonies grew even though plates were mostly filled with one or two predominant types of colonies. PDA plates grew mold, R2A plates grew swarmers and mycoides, and LB plates grew big white colonies, but all plates had some unique colonies and even ones with rings of no growth around them indicating inhibition of other colonies. One small white colony with a distinctive texture on an R2A plate showed clear inhibition of a larger colony, but didn’t seem to inhibit another smaller colony nearby. I patched any colony that seemed to show inhibition and also any colony that looked unique, so hopefully some of these patched colonies turn out to be antibiotic producers. I calculated 170 cfu’s per gram from the 10^-3 dilution sample.

 

What media did you choose? How did you sample differ on the different media?

I chose PDA, R2A and LB because I wanted to use less nutritious media in addition to LB. In PDA and R2A, my dilutions were 10^0, 10^-1, and 10^-2, while in LB my dilutions were 10^-1, 10^-2, and 10^-3 because I didn’t want the LB plates to be too crowded nor the less nutritious plates to lack growth. Plates with higher dilutions showed less growth, but seemed more diverse – for example the 10^-3 dilution for the LB was the most diverse plate I had. The distinctions between dilutions blurred with time – by 6 days of growth all plates had a lot going on. PDA plates grew SERIOUS mold which resembled Penicillin producing molds. I even had to seal these plates up so I couldn’t patch much from these. This mold probably grew because of the mulch content in the soil. The R2A plates were overrun by small pinpoint colonies and swarmers, but this was less apparent in the most dilute sample. These also showed mycoides. LB plates were the most diverse and less dominated by only one or two types of colonies (although a large white type of bacteria enjoyed growth). 170 cfu/g in largest dilution. Most varied pigments showed up in LB – orange, brown, white, yellow. LB had the most colonies yielding inhibition.

What dilutions? (see above)

Will you need to redo any?

All plates had too many colonies to count, except LB at 10^-3 dilution which was also the most diverse plate. Thus, I plated two of each media at this dilution in hopes that I will be able to get CFU counts and more inhibiting colonies. At two days growth, R2A was more diverse than LB or PDA – interesting! Also, each plate (regardless media) showed around 40 colonies at 2 days growth.

Fun with Soil – Alexa

Where did you obtain your soil sample?
I obtained my soil sample from Peeble’s Island which is near Waterford, New York. I live in Waterford and I go to Peeble’s Island all the time when I can. I went to the beginning of one of the trails on the island, and decided to go a couple feet away from the trail and collect my soil sample there. I collected the dirt in between a tree and many smaller plants. I collected the sample about 2 inches below the surface since there was a lot of leaf litter on the top layer.

Why did you choose this location?
Since Peeble’s Island is home to many different kinds of trees, plants, and wildlife, I thought it would have very rich soil. I was also curious to see what kind of bacteria I could find in a place that I had spent so much time walking around!

Do you expect a lot of isolates? Why or why not?
I expected a lot of isolates because I expected the soil to be rich since it supported such a wide variety and large amount of plants. The soil also seemed like it would get enough oxygen to support aerobic bacteria which is the kind we are growing in the lab.

Have you initial observations supported this?
My initial observations have supported this. I was only able to determine a cfu for one plate which was on PDA and a dilution of 1:10000. All of the other plates had way too many colonies to even count, even after incubating for only 48 hours. The 1:100 dilutions were completely covered with bacteria on all the different medias I used.

What media did you choose? How did you sample differ on the different media?
I chose LB, AC, and PDA for my media. Everybody had to use LB, but I wanted to use another rich media to see how many different bacteria I could grow. I realized that since my soil was likely rich, I would need to use the weakest dilutions on LB and AC since they would support the most growth. I knew I needed to use a minimal media, so I chose PDA as my third media. I noticed there were more potential antibiotic producers on the rich media compared to the minimal media, but there was significantly more diversity on the minimal media. The most common colors on the rich media were off-white and there was occasionally a yellow colony. On the strongest dilution of PDA most of the colonies were pretty small and close to white. On the weaker dilutions there were more colors including pure white, off-white, yellow, orange, purple, dark brown, and green. There’s also fuzzy bacteria (or potentially mold) growing on the PDA plates which hasn’t grown on the rich media plates.

What dilutions?
I plated the 10-2, 10-3, and 10-4 dilutions for all of the media since I guessed the 10-1 dilution would have too much bacteria in it.

Will you need to redo any?
I am redoing the 10-4 dilution on PDA since it was my most interesting plate. I am also plating a 10-5 dilution on LB and AC since I couldn’t get a cfu on any of those plates.

Fun with Soil- Sofia Boswell

Where did you obtain your soil sample? Why did you choose this location?
I obtained my soil from a flower bed located outside of my house. I chose this location partially out of convince, but also because it seemed like it would be a fairly rich soil, seeing as it was supporting a substantial amount of plant growth. To obtain my sample, I dug down about 1.5-2 inches, to collect some of the darker and wetter soil, and avoid some of the mulch on top.

Do you expect a lot of isolates? Why or why not?

Seeing as this is fairly rich soil, I was expecting a good amount of isolates to grow. The soil I chose was much more clay like, and was fairly wet since it had just rained. Since we had learned that clay-like soils tends to support the growth of more anaerobic microbes.
Have you initial observations supported this?

So far, I have observed a lot of growth on all of my plates. Each one of my plates produced growth, and there is a lot of diversity of color, shape, and size among the colonies on each plate!
What media did you choose? How did you sample differ on the different media? What dilutions? 

Initially, I chose to use LB, AC, and R2A, my reasoning being that the richer and more nutrient dense medias would support the rich and presumed microbe dense soil. I chose to plate my 10^-2, 10^-3, and 10^-4 dilutions on each type of plate. After a few days of incubation, observations indicated that R2A grew the most diversity of microbes, however there was significant growth on the LB and AC plates as well. The 10^-2 plates of all three media were fairly overgrown, but still had some very interesting colonies. The 10^-3 plates were all very diverse and gave me the most useable colonies for my patch plates. The 10^-4 plates all had low amounts of growth, however this allowed my to obtain a definitive colony count, from which the cfu could be calculated.


Will you need to redo any? 

I chose to redo all three of my 10^-3 plates to see if I got anymore interesting growth. I also decided to make two more 10^-3 plates, using the PDA and 10% TSA medias, since these are both minimal medias and my R2A plate had yielded the best results. I wanted to see if these media types would result in similar growth.

2. Fun with Soil – Brianna Cummings

Where did you obtain your soil sample?Why did you choose this location?

I collected my soil sample between the pyramid and the bank of the Hans Groot Kill.  I dug about an inch down, and tried to avoid the grass and roots that were in the soil.  I chose this location for two reasons. The first being out of sheer convenience. The location was right on the way to class, so I was able to just wake up 15 min early and be set with collecting my sample. I also chose this location because I thought there would be some interesting bacteria found there due to the activities that happen on and near the pyramid.

Do you expect a lot of isolates? Why or why not? Have you initial observations supported this?

I expected to get a fair amount of isolates due to the location and soil type. The soil was clay-like and as mentioned in class this tends to support more anaerobic microbes. However, since my sample was collected from the top layer of soil, I figured there would still be a good amount of aerobic microbes. I also thought due to the highly trafficked area (and activities that go on there), there would be a lot of different microbes. Also the sample was collected near the creek, and after hearing how there’s lots of stuff in the water during class, I again thought there would be plenty of microbes in my sample. Initial results have proven that my sample has a good amount of microbes in it, yet the diversity is lacking (the majority of colonies are off-white and round with very similar morphologies).

What media did you choose? What dilutions? Will you need to redo any? How did your sample differ on the different media?

I chose LB, R2A, and PDA media. Since I thought there would be lots of microbes in my sample I chose to do two of the less rich media and only the LB rich media. For similar reasons, I used the higher dilutions of 10^-1 through 10^-3 (numbering system in book) for each of the medias. Interestingly, the R2A had very rapid growth of both colonies and mycoides, and needed to be diluted to 10^-4 to obtain accurate counts. As for the different media, it mostly affected the diversity of the colonies rather than the number of colonies. For instance, the R2A tended to have mostly white colonies that pretty much looked the same and mycoides, whereas the PDA had many different morphologies and colors. LB samples tended to be somewhere in the middle regarding morphologies- there were many similar ones, but there were also some unusual/unique looking ones.

Fun with Soil – Minh

Where did you obtain your soil sample?
I obtained my soil sample from the plaza that is located in between Olin, Wold, and S&E (right outside the Starbuck’s exit). The exact coordinates are 42.8175459, -73.9278173.
I dug about 2 to 3 inches below the surface next to the shrubs that are situated outside of Olin.

Why did you choose this location?
I was working late at night in my lab in Wold, so I did not want to go too far to obtain the sample. The location did not seem like a “rich” site because only some shrubs are present there but across those plants was a closed-off ground due to the presence of asbestos, so that convinced me to pick the soil from that location.

Do you expect a lot of isolates? Why or why not?
Not necessarily. As I mentioned above, the site in that area does not have a lot of diverse plants as there are mostly shrubs and grass. However, the soil might be actually quite fertile as it is the property of Union College and the school probably uses rich soil for the plants.

Have you initial observations supported this?
On the first day, 24 hours after plating, there was a lot of growth for every different media that I used at the 10^-1 dilution. Other dilutions had some growth, but there were not as many colonies as on the 10^-1 plate. In addition, after 78 hours, I could start to see a diversity of different colonies being grown as there were plenty of different colored and shaped colonies present on the plates. This suggests that the soil was much richer than I had initially assumed.

What media did you choose? What dilutions?
For the media, I chose to use LB, 10% TSA and PDA plates. As for dilutions, I spread 100 µl of each 10^-1, 10^-2, and 10^-3 dilution for every different plate.

How did you sample differ on the different media?
Every plate had something particular that made it distinct from other plates which made the plates to be very interesting. LB had some different colonies, but the colonies that struck out were evenly spread across the plate; these colonies were brown in color and had a surrounding halo of similar color around them. 10% TSA plates had some diversity, but the colonies were rather small with less diverse pigments; there was a presence of mycoides on these plates as well. PDA plates were the most diverse, in terms of shape and color; some colonies were round and filamentous, and others were colored from light yellow to dark brown or even pink. However, most importantly, every plate contained some colonies that showed inhibition as they inhibited the growth of the neighboring colonies.

Will you need to redo any?
I did not redo any of the dilutions however I did additionally plate a new dilution,10^-4, for LB and PDA plates so that it would easier for me to count the number of colonies that grew on the plates.

 

Fun With Soil – Troy

Where did you obtain your soil sample?

I obtained my soil sample from outside the new S&E building next to the construction site.  Professor Salvo suggested this location, because she felt there would be interesting organisms there since the soil had not been turned over in many years.

Why did you choose this location?

Having stagnant soil allows for the growth of many different bacteria without disturbing any of them.  I chose this soil sample, because Professor Salvo and I knew there would be interesting organisms present that had not been disturbed in many years.

Did you expect a lot of isolates? Why or why not?

I expected some isolates, but I didn’t expect too many – the soil was sandy in texture and I thought that the organisms present would have a difficult time finding nutrients.  I did, however, think that this would make them more likely to produce antibiotics to fight for these nutrients.

Have your initial observations supported this?

My initial observations were that the bacteria grew out of control on my less dilute plates, but they grew beautifully on the more dilute plates.  I have also noticed a substantial amount of what appears to be AB production, but I will only know if this is the case after further analysis!  My observations that the less rich media (R2A) grew fewer bacteria was supported by the decrease in growth at the same dilution levels as the LB and AC plates.

What media did you choose?  How did your sample differ on the different media?

I chose the R2A (less rich), LB (rich), and AC (rich) medias.  I did this to support both bacteria that thrive in low nutrient environments as well as those that thrive in nutrient-rich environments.  I noticed that the bacteria grew at about the same rate in the R2A as the AC and LB when it was at a dilution 10 times less than the rich counterpart.  For example, when R2A was at 10^-1 and LB and AC were 10^-2 it seemed that they were closely related in growth.

What dilutions?

I ran my R2A at 10^0, 10^-1, and 10^-2 while I ran the LB and AC at dilutions of 10^-1, 10^-2, and 10^-3 dilution factors.

Will you need to redo any?

The dilutions worked beautifully.  The best example I can give of how well the dilutions worked was from the LB plates.   The 10^-1 plate had too many colonies to count, but the 10^-2 plate had 90 and the 10^-3 plate had 9 colonies.  This showed that the dilutions were accurate, and the plates were growing as expected.

2. Fun with Soil -Carly B

I collected my soil sample from the lawn in front of the Nott on campus. I dug down about an inch and then filled my test tube with soil and tried to avoid getting grass in it. The GPS coordinates were 42.8173 degrees N, 73.9300 degrees W.

I chose this location because I was interested in seeing what kind of bacteria was growing there since many students sit on the lawn in front of the Nott when it is nice out. I also wanted to see what was there because I know that lawn is constantly treated to keep up its appearance.
I do expect a lot of isolates because the lawn is treated so much that it makes it rich and good for sustaining the growth of the lawn and also bacteria.

So far this has been reflected on my culture plates. There has been a lot of growth and even a lot of overgrowth on most of my plates including the plates with less concentrated dilutions. I couldn’t count any of my plates from my first round of plating because they were so overgrown.

I chose to use LB, R2A, and AC for my media. I chose LB and AC because I figured the complex media would reflect their natural, rich environment of the lawn so I was confident I would get growth even with higher dilutions. I used R2A because I wanted to plate a minimal media since I figured the soil was so rich with bacteria that there might be almost too much bacteria to work with.

I plated a zero dilution, a 10^-1, and a 10^-2 dilution on R2A because this was the minimal media so I figured I should test out the more concentrated dilutions. I plated 10^-1, 10^-2, and 10^-3 dilutions for LB and Ac because they were the complex media so I figured the bacteria would grow more easily on this media and a less concentrated dilution would be the best to use.

Since pretty much all of my plates were overgrown and I couldn’t count cfu’s for any of them, I had to replate some dilutions. I replated a 10^-3 dilution on AC and R2A because I thought that if I left them in the incubator for a shorter amount of time before looking at them that I’d be able to count them and pick more isolated colonies and this was correct. I also replated a 10^-4 dilution on LB, AC, and R2A because there was overgrowth on all of my 10^-3 plates from the first round of plating so I thought doing a dilution with a lower concentration that it would be even better work with, however these plates barely had any growth after 2 days.

All three of my media had a lot of growth. I chose the fewest colonies from the R2A plates because those plates had some good colonies but there were a lot of extremely small colonies that were very close together which meant I couldn’t pick individual colonies up very easily. The LB and AC also had a lot of good colonies but they were very overgrown so it was hard to pick individual colonies. The colonies were overall larger on AC and LB and also more diverse.

Fun with Soil – Nikki

Where did you obtain your soil sample?

I decided to collect my soil sample from Union’s Octopus Community Garden on campus. I took the sample an inch or two down, just below the surface, so that I did not get the hard topsoil/mulch and it was near bulbs that were growing (I assumed they were onion bulbs). GPS coordinates- Latitude: 42.8 degrees Longitude: -73.9 degrees.

Why did you choose this location?

I chose this location because I thought it would be interesting to look at something available right on our campus that many members of the community use or partake in on a regular basis. I also expected the soil to be “rich” due to its use in the garden to grow vegetables and various plants.

Do you expect a lot of isolates? Why or why not? 

Yes! I expected there to be a lot of isolates due to the rich nature of the soil being used for gardening purposes. I also thought that maybe because various plants and vegetables grow there that there may be more diversity depending on what has been grown in that location now and previously. In addition, there are a lot of people that work in the garden there that could contribute to what is in the dirt.

Have your initial observations supported this?

Yes, I have a lot of growth on my plates. It seems like I have a lot of growth and a decent variety because many of them look different in their coloring or morphologies. The only countable plates I had were on the 10^-4 dilution plates.

What media did you choose?

I chose 10% TSA, LB, and AC for my three. Prof. Salvo suggested that everyone in the class should use LB for one of the choices. Then I chose 10% TSA and AC because they were for cultivating a wide variety of microorganisms, according to their descriptions in the handout. I thought I would have a wide variety for my soil sample and so I chose these two.

What dilutions?

I plated 10^-2, 10^-3, and 10^-4 dilutions on my plates for each of the three media. (However, going by the way the book does it, these need to be changed to 10^-1, 10^-2, and 10^-3).

Will you need to redo any?

I had growth for all of my plates at the various dilutions, but I decided to re-plate a few. My plates with the AC medium still had too many colonies to count and lots of growth making it difficult to distinguish, so I went one dilution further, 10^-5 (which is actually 10^-4 according to the book) and plated two of these. I am still waiting for these to determine the CFU, but after two days there is no growth yet. I also did one more plate with LB and 10%TSA at a 10^-4 (actually 10^-3) dilution because these were countable, but there were a few large growths and I wanted to compare to get a more accurate CFU. I am still waiting a few more days to get a count because after 2 days there were 2 colonies on the 10% TSA plate and no growth on the LB plate.

How did your sample differ on the different media?

All three had a decent amount and variety on all the different media. AC had the least “pickable” colonies and I was only able to pick 14 (hopefully the new plates will provide more) because mycoides were present as well as really large growths. The LB and a few from the 10% TSA had a very dark brownish pigment sort of radiating from the circular shape and no other growths around it.

Fun with Soil – Kara

“Where did you obtain your soil sample? Why did you choose this location?”
I obtained soil from under a tree that was located near my dorm. I chose this location because the day I collected soil it was very wet outside, so the soil under the tree was drier than most other soil. I also chose this location because it is near the dorm compost bin. I figured maybe because of the proximity to the compost there would be some interesting growth.

“Do you expect a lot of isolates? Why or why not? Have your initial observations supported this?”
I didn’t really know what to expect when I collected the soil. It was close to the compost, which likely has a lot of microbes. However, the soil under the tree is rather protected. My initial observations showed less robust growth than I expected. My CFU was only 4.5-1.2 10^6 colonies / gram of soil.
When I let the plates grow for several days there was more growth, but there appear to be only a few different types of colonies.

“What media did you choose? What dilutions? Will you need to redo any? How did you sample differ on the different media?”
I decided to use 2 “rich” medias-LB and AC, and 1 “less rich” media-PDA. I chose the 2 rich medias because I was unsure how rich my soil sample was in microbes. I chose the PDA because it was mentioned in class lecture that several microbes that produce antibiotics like to grow on PDA. I originally plated 10^0,1, and 2 dilutions of media in PBS. I had to redo a few because I waited 5 days (I was away over the weekend) to look at my plates, and they were all too dense to collect a CFU and patch colonies. I then plated more of the 10^2 and 10^3 dilutions on all 3 types of media, so individual colonies were more identifiable. My PDA plates were also covered in a thick slime, which was potentially hazardous so I threw it away. The AC and LB plates showed similar growth–mostly small, white, gray, and yellow, round colonies.

(P.S.) if I accidentally replied to people my apologies! it took me a few tries to get this is the right spot

Fun with soil- Nicole B

Where did you obtain your soil sample?
I got my soil sample in the manure pile at the barn my aunt rides at, Graystone Stables. I tried to go to the older and farther back part of the pile, and I took my sample from a layer about two inches below the surface of the pile.

Why did you choose this location?
I figured that not many other people have searched through a manure pile, and going to an actively decomposing mix of hay, wood shavings, and horse poop would reveal more than taking a sample from already spread dirt. I went to the back to try to get at a point where the feces was already decomposed to avoid fresh ones. I noticed three distinct layers in the manure pile: a top layer of dry but still presumably nutrient rich stall products, a middle layer of moist, dark, and slightly warm stall products that I assume was actively decomposing, and a bottom layer of dry and crumbly hay and soil. I took my sample from the middle layer.

Do you expect a lot of isolates? Why or why not? Have your initial observations supported this?
Yes, I did. Not only did I know that the results of a manure pile can support a lot of growth, the soil was warm to the touch due to the decomposers (I washed my hands afterwards). My observations have definitely supported this because I have an uncountable number of colonies even on my 10^-3 dilution plate.

What media did you choose? What dilutions?
I selected LB and AC media because they were nutrient rich and I figured the bacteria in my soil sample would like that, and I chose 10% TSA because it would make a good representation of bacteria that didn’t thrive in rich environments. I also didn’t have many others to choose from. Due to a misunderstanding of dilution, I made 10^-1, 10^-2, and 10^-3. I also made a 10^0 dilution just to see what that would look like, and threw it away after realizing it wouldn’t give me much data.

Will you need to redo any?
Over the weekend, I noticed that my 10^-3 dilution plates had a ton of colonies, making it uncountable (or really difficult to count). On Tuesday, I made 2 spread plates at a 10^-4 dilution for each media I used. The plates are in the incubator right now and are growing.

How did your sample differ on the different media?
So far, I’ve noticed that there are more green and blue tinted bacteria colonies on the 10% TSA plates than on the other plates, but the colors could simply be more noticeable due to the whiter color of the media. The 10% TSA plate also had white/grey colonies with rhizoid arms on the border. There were a couple of colonies on the AC plate that appeared to tower over the rest of the bacteria, rising about 0.5 cm above the plate. The LB plate had more fuzzy colonies on it, and I noticed more brighter yellow colonies on the plate compared to AC.

Fun With Soil- Kelsey

Where did you obtain your soil sample?
I collected my soil from my backyard here at school. I live at 22 Union Ave. If you walk into my back yard there is a parking lot that leads to two other houses– 20r and Carriage House. I collected the soil next to the cement wall that separates our houses from a house nearby. I have attached a picture below! I dug about 2.5 inches down to get a better soil, rather than a sandy, beer can infested selection. 

Why did you choose this location?

I chose this location because the two houses behind my own tend to have a lot of outdoor parties. I thought that I would get a lot of interesting bacteria due to the wastes and circumstances this environment is exposed to.

Do you expect a lot of isolates? Why or why not?

YES! I think that I will get tons of cool stuff from this dirt. I think that because this location is exposed to both human and animal waste that I will get a lot of interesting isolates. I also think that because there was some rusty old objects mixed in with the dirt, I am even more apt to get some interesting isolates.


Have you initial observations supported this?

Yes, I have had a lot of growth on my plates! The smallest CFU that I have is 2.16×10^6. I think this is a great number. I have had a lot of diversity with my plates as well. Lots of different shapes and colors of the colonies.

What media did you choose?
I chose three types of media– LB, R2A, and AC. I found that LB had the best growths, AC had a lot of overgrowth, and R2A provided the most diverse growths (but had mycoides at the lowest dilution).


What dilutions? 

I plated 3 different dilutions on 3 medias– totaling 9 plates. In terms of the books explanation the three dilutions were 10^-1, 10^-2, and 10^-3.

Will you need to redo any? 

I did not necessarily need to redo any, but I decided to plate 1 plate of R2A with a 10^-3 dilution, 1 plate of AC with a 10^-2 dilution, and 1 plate of LB on a 10^-3 dilution. I decided to do this in order to achieve even more diversity with my plates!

How did you sample differ on the different media? 

The sample differed across media in a few ways. AC with the sample caused a major overgrowth of one colony. The R2A and sample had mycoides growth across all dilutions except for 10^-3. The LB had the most variety of growth. I think that R2A provided the most diversity, with LB a close second. I would choose them to plate more if my new plates are unsuccessful.

Fun with Soil – Jill

Where did you obtain your soil sample?
My soil sample came from an old cedar sawmill site in the Adirondacks.  The mill was probably active in the 1920s and 30s, so while nothing remains of the mill itself, the deep pile of sawdust has settled and lacks any growth.
Why did you choose this location?
I was curious – I wouldn’t think was was a “rich” site, but might have some very selective types of microbes.
Do you expect a lot of isolates? Why or why not?
Not really. I figured the site was toxic, since after almost 100 years no trees or other plans have colonized the site.
Have you initial observations supported this?
Well – I was surprised how much grew, but I did plate the original suspension (the “no dilution” sample) as well as the 10 -1 and 10-2. But my cfu is relatively low – around 106 cfu/g.
What media did you choose? How did you sample differ on the different media?
Well – I did try all the medias to see what kind of differences I might see. I actually got more growth on the less nutrient media. Both LB, AC and R2A were very similar – low growth ( LB was 4.5 x 105) with mostly white plain looking colonies, very little diversity.  PDA definitely had the most diversity with a number of dark pigmented colonies – from dark brown to tan to reddish brown. I picked more form this plate as a result.  The 10% TSA had diversity, but less with pigment, some looked liked they might be filamentous. I saw no mycoides on the plates.
What dilutions?
(see above)
Will you need to redo any? I did plate a 10-3 dilution of each, but I don’t expect much more. As of 24 hours, nothing has grown.

2. Fun With Soil

(due Friday September 21 evening)

So I am really curious about your soil samples! so let’s share:)
Where did you obtain your soil sample? Why did you choose this location? Do you expect a lot of isolates? Why or why not? Have you initial observations supported this?

What media did you choose? What dilutions? Will you need to redo any? How did you sample differ on the different media?

2a.  Share your thoughts with at least two of your classmates
          (due Monday September 24 evening)