“Teach me,” she said.

[Cecily]

Obligate anaerobe or facultative anaerobe, I think I'm wrong about that. O or O-F result would differentiate aerobes/facultative anaerobes from obligate, but I think that actual test is oxidase.


Blargh. P putida, I think is oxidative but not sure on fermentation. A different type of Pseudomonas is oxidative, but negative on anaerobic fermentation.
Call that positive for oxidation and be done w/ it.



TSI done

[Cecily]

Finished! That took 3 hours lol. Very last bacteria I was checking I found this: Database of Biochemical Tests of Pathogenic Enterobacteriaceae Family

Doesn't cover everything and I had to figure out that d-glucose acid production / d-glucose gas production = phenol red broth, but exactly what I need in the future and good resource for paper! Erwinia amylovora is in enterobacteria family and that is the bacteria that's gonna make apple trees extinct eventually, I think. Probably doing it on that.

[DMN]

Hopefully you actually understand the tests and how to interpret the results, and you didn't just look up the results on the internet to fill them in. You will pay the piper on exam/practical day.

[Cecily]

I was driving at that. Extremely inefficient and borderline disrespectful use of my time, pretttty sure our manual / text doesn’t have a differential reference, but I have a much better idea of how the tests operate than I got while scrambling to go through the physical motions rushed in the lab. I gained a few points in research and found some sources I plan to come back to help with course and personal interest.

From the top of my head (and this is all “new” information acquired today I’ve long since forgotten about when I did it before) :

O-F tests how / if an organism metabolizes sugar, seeing if ferments glucose in the presence of oxygen or if oxygen is toxic to it. That’s alot of variables that I haven’t quite gotten my head around, and I think we’re basically we’re seeing how deep into the Krebs cycle something gets, oxygen needed for oxidative phosphorylation in aerobic respiration’s electron transport chain = most efficient use of glucose for ATP.

Hazy on krebs, but I think each turn gets you 30+ 2 or 4? some ATP. Earlier step of glycolysis is way less efficient, so I’d make the assumption that anaerobic organisms reproduce much slower simply due to less available energy than ones that can survive in O2. Need to ask if I’m right on that.

Triple sugar iron test I need to look into more because the results are complicated. There’s like 8 different variables, glucose fermentation or glucose AND sucrose and or frutose, and also if it reduces sulfur. There’s also an indicator for metabolism of animal proteins. There’s a reaction with acid from fermentation that turns into black percipitate when sulfwr reduction happens.

Phenol red broth, this is the only one I actually know the indicator for (hint: phenol red) and I need to fix that in the future, but this can be glucose/ sucrose/ frutose as a differential, I’m assuming. But what it does is change color to yellow from red if fermentation happens when the ph drops to 6.8 or lower from the acid. If some p word happens the solution the solution turns pink from the alkaline end products. There’s also a tube floating in the solution that gets a bubble in it if fermentation produces gas. That gives you 3 or 4 results, depending.

As far as what bacteria does what, that’s all white noise atm and I need to see how relevant knowing that is to my grade. I think the concepts and characteristics are the focus here. The big picture in this lab from what I can see is these are simply various ways to test for fermentation of carbohydrates with slightly different variables.

[Cecily]

Question I have is wtf is fermentation? Lol. Feel like that’s a bad point to miss! Krebs cycle is fucking scary to look at and I need to learn the simplified version again to really get this.

Ok so it’s glucose molecule -> glycolysis -> two pyruvates and depending on O2 availability it goes either through oxidative respiration (big atp) or fermentation (acid, gas, alcohol byproducts depending on type of fementation).

I thought fermentation happened under anaerobic conditions and O-F test had me thinking it happened in both.

Fermentation = 2 ATP per glucose
Krebs = 36 + 2 ATP per glucose

Legit scared of this thing. I used to know it.
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https://wikispaces.psu.edu/display/2...ric+Acid+Cycle

[DMN]

Originally Posted by Cecily [You must be logged in to view images. Log in or Register.]

Question I have is wtf is fermentation? Lol. Feel like that’s a bad point to miss! Krebs cycle is fucking scary to look at and I need to learn the simplified version again to really get this.

In micro the definition is generally: the ability to metabolize sugars(produce ATP) without oxygen(anaerobically).

[DMN]

Originally Posted by Cecily [You must be logged in to view images. Log in or Register.]

I thought fermentation happened under anaerobic conditions and O-F test had me thinking it happened in both.

No, the F in OF is specifically for fermentation. if you get a change in PH in the "F" part of that test, the organism can use fermentation for a metabolic pathway.

[TheSurgeon]

Originally Posted by Cecily [You must be logged in to view images. Log in or Register.]

Question I have is wtf is fermentation? Lol. Feel like that’s a bad point to miss! Krebs cycle is fucking scary to look at and I need to learn the simplified version again to really get this.

Ok so it’s glucose molecule -> glycolysis -> two pyruvates and depending on O2 availability it goes either through oxidative respiration (big atp) or fermentation (acid, gas, alcohol byproducts depending on type of fementation).

I thought fermentation happened under anaerobic conditions and O-F test had me thinking it happened in both.

Fermentation = 2 ATP per glucose
Krebs = 36 + 2 ATP per glucose

Legit scared of this thing. I used to know it.
[You must be logged in to view images. Log in or Register.]
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https://wikispaces.psu.edu/display/2...ric+Acid+Cycle

So, no shit, I spent a lot of time memorizing the entire CAC for the MCAT, knowing, just knowing they would ask a question that required you to memorize it. The one question about it on the test they had the entire cycle displayed in an image involving the question. Such a god damn waste of time.

[DMN]

And speaking of 99%, I think the level you are at that they won't throw crazy stuff at you like obligate anaerobes that can still ferment in the oxygen exposed tube. As long as you know the basic gist I think it will be fine. But they might have wanted tyou to memorize all the attributes of the bacteria you are looking at. So you might have to know(memorize) for instance that e.coli is a facultative anaerobe. Usually your instructor gives some tips about whats going to be on it.

[Cecily]

Yeah I think I’m gonna backtrack and start making a study guide of everything we’ve done so far before it gets to be too much.

Looks like we’re doing a bunch of enterobacteriaceae (I love that word) differentials tomorrow. I actually read the procedures and know what I’m doing this time. Also have copious notes on the test, why it’s used, what chemicals are involved, what results mean what along with the procedure.

Indole/SIM medium
Methyl Red and Voges-Prokauer tests
Citrate Test

Actually looks like a pretty chill day. Stab, broth, and a slant. That’s good because I’m exhausted. Learned a lot today. Gn!