This is your brain. This is your brain on Microbiology…

In an effort to eat a relatively healthy diet, I occasionally eat pieces of wholesome, natural fruit.

There, I’ve admitted it. I can no longer live the lie that I only eat junk-food. Of course, to maintain some appearance of having a normal mainstream type of diet, I at least tend to go for the pre-cut fruit mixtures – I’ve got way too much going on to have time to prepare cut fruit salad from scratch.

Anyway, a few weeks ago I had a platter of these, still sealed in their plastic container, and didn’t get around to eating them in time. About a week after it had expired, when I went to throw it away, I saw a few little white lumps growing all over the pieces of fruit. Non-fuzzy, so I expected they were bacterial rather than fungal. Of course, there’s only one thing I could think when I saw that.

“Oh, wow! It looks like there were only about 5-8 bacterial CELLS on each piece of fruit when I got them! Those things were really CLEAN!”

(Of course, once you can SEE the colonies growing, there are a lot more than a few cells there. Each visible colony’s probably got millions of the little buggers, but each colony starts as a single cell.)

This was, of course, followed by me lamenting that I didn’t have some culture supplies and a microscope of my own to examine them with. Sigh. Anybody out there have any extra microbiology equipment you’d like to donate to a good cause?

So, what’s next? Should I try to start a series of bacterial taxonomy posts? Searches for “what’s a gram-positive?” and “what’s a gram-negative?” sorts of questions seem to be popular ways to reach this blog…

Poisoning Prokaryotes in the Park

(Well, okay, it was a “Pathogenic Microbiology Lab”, not a “Park”, but whatever).

Antibiotic Susceptibility of a Poor, Innocent Microbe

Objective:Experience the awesome power of the mighty Antibiotic Susceptibility Test, wielded against an unsuspecting bacterial organism!

Introduction:

Every day, billions of innocent bacteria are ruthlessly slaughtered by antibiotic substances introduced into their callous, inconsiderate hosts. Condemned to death as nuisances due to nothing more than the potential inconvenience of debilitation, tissue necrosis, death, halitosis, and other minor problems, the unstoppable might of all medical science is focussed on our prokaryotic friends like medical professionals around the world focussing the rays of the sun through a thousand magnifying glasses to obliterate innocent prokaryotic “ants”.

The ?-lactam antibiotics – the blahblahcillins (Penicillin, Ampicillin, etc.) and the Cefablahblah compounds (Cephalosporin, Cephalothin, Cefuroxime, etc.) all interfere with the formation of the bacterial cell wall – loosely analogous to the human epidermis. This treatment viciously targets the hardest-working, actively-reproducing bacteria, spilling their guts as they attempt binary fission, while leaving the lazy, dormant microbes alone. Gram-negative bacteria are somewhat protected from this torture by their outer membrane, but some (such as ampicillin) can affect even some of them. Gram-positives, with their simple structure, are hardest hit. A few microbes have learned to counter this by secreting an enzyme which disables many of these drugs, though medical science has countered with clavulanic acid – an inhibitor of the ?-lactamase enzymes. Enzymes resistant to inhibition by clavulanic acid are being developed as part of this continuing arms race.

Chloramphenicol is an artificially manufactured bacteria-poisoning chemical synthesized in laboratories (though it was originally obtained during interrogation of a captured Streptomyces species) which interferes with protein synthesis at the 50s ribosome. Erythromycin has the same affect, by a slightly different mechanism, and is a macrolide – a class of large molecules with lactone rings which resemble in shape the poisoned ninja throwing-stars seen in movies. Both of these chemicals are bacteriostatic rather than bacteriocidal, but are broad-spectrum. Chloramphenicol’s devious action sometimes backfires on a small number of people, causing potentially fatal aplastic anemia.

The Sulfonamides are also bacteriostatic, and are competetive inhibitors of enzymes that convert the nutrient PABA into biochemical products vital for prokaryotic health. Much like a hypoglycemic person with diarrhea given a “cupcake” made entirely out of Olestra® and Sucralose, the microbial victim of this chemical ingests it but finds that it merely inconveniences the metabolic processes rather than feeding them.

Tetracycline (the first of the Tetracycline-type antibiotics) and Tobramycin (an Aminoglycoside) both jam the gears of protein synthesis, inhibiting the action of the ribosome in the former case, and actively causing erroneous protein formation in the latter. The latter effect is outright bacteriocidal, causing the poor bacterium’s protein assembly systems to make broken enzymes until the cell’s protein factory is bankrupt and has to lay all the enzymes off. Tetracyclines appear to only slow down the cell, but in the cutthroat competition for cellular activity in the human body, this stumbling can be a death sentence for the business of prokaryotic replication.

In order to determine which of these lethal agents to deploy against the oppressed bacteria, a medical professional may capture a microbe and torturously test various agents on it, watching without emotion to see which ones destroy the microbe most efficiently. This awful, coldly clinical process is standardized in the Medical Microbiologist Field Manuals on Interrogation as the “Kirby-Bauer”[1] antibiotic susceptibility test. In these tests, 6mm diameter paper disks soaked with various antibiotics in specific amounts, is pressed onto a growing young microbe culture to see which ones are most destructive, leaving desolate areas devoid of life in the culture…

Recently, we got to do this..

Materials and Methods:

A colony of Pseudomonas aeruginosa was lured into a culture tube with the promise of free candy. Happily replicating, this culture was transported to a secret location containing Mueller-Hinton agar. 100?l of this culture was told that it had won an all-expense-paid stay at a four-star hotel with room-service, and was plated onto the agar. The culture was then strapped down and tortured for its secrets by application of 12 antibiotic-soaked disks. The torture was performed at 37°C for 24 hours, and the results measured with a ruler.

Results:

The defiant Pseudomonas organism bravely withstood the application of Ampicillin, Cephalothin, Chloramphenicol, “Triple Sulfa”, Nafcillin, Cefazolin, Amoxicillin with clavulanic acid, Cefuroxime, and Penicillin G. Erythromycin seemed to cause the subject some discomfort. It was not quite able to grow to the edge of the antibiotic disk all the way around but was able to get within less than a millimeter of it, even touching it in a few spots. Tetracycline was unbearable to the subject, who was limited to a 11mm (diameter) zone of inhibition around the Tetracycline-containing disk. Finally, Tobramycin (zone of inhibition approximately 23mm) finished breaking of the subject, who then confessed to several murders of immunocompromised individuals, robbing a “Wal-Mart”, and once molesting an archeaean of the genus Thermoplasma. Investigations may already be underway to determine the authenticity of these confessions. Then again, they may not.

Conclusions and Discussion:

Pseudomonas aeruginosa is a hardy little bugger who can put up with a wide variety of antibiotic insults. Its weak point appears to be its ribosomal machinery, as this was the target of the three drugs which had any apparent effect. Should intelligence indicate the threat of attack by the terrorist Pseudomonas organization, ribosome-targeting, protein-synthesis-inhibiting agents should be deployed as a countermeasure.

References:

[1] – Bauer AW, Kirby WM, Sherris JC, Turck M, “Antibiotic susceptibility testing by a standardized single disk method” Am J Clin Pathol. 1966 Apr;45(4):493-6

[2] –Tortora GJ, Funke BR, and Case CL, “Microbiology – An Introduction (sixth edition)” 1997, Benjamin/Cummings Publishing Company, Menlo Park, CA

I am filled with shame…

It’s been a long day away from home, and I’ve got nothing much prepared for tonight – the last day of “Just Science” week. (Not that I’m going to stop posting after today or anything…)

So, I’ll cop out, and instead post a question.

What textbook(s) are you currently using for Microbiology classes, and what do you think of them? My “Introductory Microbiology” class was over 8 years ago, but the textbook was Tortora, Funke, and Case – “Microbiology: An Introduction (sixth edition)”.

I found it annoyingly heavy on the “disease-listing” and way too sparse on the rest of the microbial world – though they did have a couple of chapters on applied/industrial type microbiology.

Please leave comments…

My posts will likely be pretty sparse until after Wednesday, when I have back-to-back Microbial Genetics and Pathogenic Microbiology exams. Ick. As you can imagine, I’ll be studying a lot for the next few days to make sure I’ve learned what I’m supposed to up to this point.

Curse you, public library!

Tonight’s post will be an eclectic one…

I made the mistake today of heading for what passes for a “large city” in my local area in a general need to go somewhere besides my house and the college. I figured I could browse the local discount bookstore and see if they had anything interesting.

I happened to notice a sign advertising a book sale at the local library.

Why did they have to do this to me? Have they no decency? Have they no shame? Have they no MERCY?

As I previously mentioned, I actually do collect old science (and medical) books. Unfortunately, I ended up walking out of the library with a whole mess of microbiology books (and one Botany book that I picked up just because it was old – 1930’s). Fortunately, they were cheap.
I was just perusing one of the books I picked up: an old “Bacteriology” book[1] from the late 1940’s. It’s fascinating and instructive to see what scientists used to believe was true and what observations led them to believe it.

The introductory chapters of the book include a discussion of taxonomy and the place of “Schizomycetes” (meaning bacteria that aren’t photosynthetic) in the overall scheme of things. There’s a discussion that, given what information was available at the time, is perfectly reasonable and explains why bacteria are “plants”, just like other fungi (Fungi, you see, are just plants that aren’t photosynthetic – or so they explain). The author gives a classification scheme for plants that divide them into three categories, which roughly equate to “normal” plants (with stems and leaves), moss-type plants, and plants that don’t have roots, leaves, stems, or flowers. This latter category he broke into two sub-categories – Algae (including “Blue-green” algae, which we now know are actually bacteria) and Fungi. “Bacteria” are listed as one of the categories of Fungi.

The discussion justifying this categorization makes some interesting claims – some of which are startling to me. The author claims that some bacteria – “Acetobacter xylinum” have cell-walls that consist of cellulose, just like plants. (Actually, it would appear this bacterium does make cellulose, though I don’t think it’s actually a component of the cell wall – this is a standard “Gram-negative” type ?-proteobacterium). I had no idea up to this point that there were cellulose-producing bacteria. Interestingly, the author also states

“Some bacteria are said to possess cell walls of chitin, a distinctly animal substance which is the material of horn, hair, hoof, and insect shell”

which is completely wrong on every count except for the part about insect shells. (Horn, hair, and hoof (and fingernail) material is Keratin, which is a type of tough protein. Chitin is actually a polysaccharide…and it is what most fungal cell walls are made of.There are some interesting statements in the section on microscopy as well. The author claims:

“There seems no doubt that the gram-positive material in bacteria is ribonucleic acid. Bartholomew and Umbreit[2] have shown that it can be removed by soaking the gram-positive cells in sodium choleate. It may be replaced by treating them with magnesium ribonucleate. Normally gram-negative species will not accept the applied coating. The specificity of these reactions is shown by the fact that an enzyme, ribonuclease, will remove the gram-positive character (ribonucleic acid) of the cells very quickly.”

What the heck?… Now I have an urge to see if I can sneak a culture of some kind of Bacillus and some RNAse and see how much of this explanation actually matches observation. (Perhaps I can dig up Bartholomew and Umbreit’s paper as well). The author also mentions that nobody has managed to get a good image of a bacterial nucleus, either, which of course is because they don’t actually have one…
One other thing I’d never heard of: Proton Microscopy. According to the author, this technique, apparently first implemented in France in 1948, could theoretically give substantially better resolution than electron microscopy.

Some quick poking around seems to show that this is partly true, and there actually are proton microscopes that get used for some kinds of studies. However, protons are a heck of a lot harder to “focus” and they don’t seem to have caught on for microbiological work. They do evidently have some useful properties for doing analysis of what specific elements are in a sample, though[3].

I noticed some other apparent differences in style between the older textbooks and current ones, but I’ll save that for another time.

I will also at some point go back and re-write the Schizomycete article to include some of the information I’ve picked up in the last couple of weeks. Meanwhile – one more day of “Just Science” week! Looks like I should survive it after all.

[1] – Frobisher, Martin Jr. “Fundamentals of Bacteriology (Fourth Edition)”, 1949, W.B Saunders Company, Philadelphia
[2] Bartholemew JW, Umbreit WW, “Ribonucleic Acid and the Gram Stain”, J. Bacteriol. 1946, 48:567
[3] “Microscopy with Protons” http://www.innovationmagazine.com/innovation/volumes/v7n1/coverstory3.shtml (visited 2007-02-10)

The “Electron Transport Chain”, Grossly Oversimplified

Why does breathing work, anyway? And can I possibly explain it in a couple of paragraphs? I don’t know, but I’m going to try…it leads into the subject that got me interested in majoring in Microbiology in the first place. It’s probably kind of foolish to try to cram in this explanation in the half-hour or so before midnight (and hence the informal deadline for getting a post up every day for “Just Science week”), but here goes:

First, a bit of really simplistic background. Since the fundamental principle of the universe is basically that stuff likes to fall apart (dang lazy molecules), in order for a cell (bacterial or otherwise) to make new proteins and strands of DNA and so on, it has to have some kind of energy that it can use to pay for the increasing orderliness that it’s causing. The chemical that’s usually used to provide this energy is ATP. The energy comes from a string of three Phosphate (PO4) groups that are attached to it. The third phosphate in the chain comes off really easily, releasing a bit of energy in the process, like a spring uncoiling. A lot of enzymes work by attaching to ATP, letting ATP fall apart (becoming the slightly more “relaxed” ADP in the process), and using the released energy to power some other process.

In order for this to work, the cell has to be constantly re-charging ADP, cramming that third phosphate back onto the end along with putting back the bit of chemical energy.

The point of this post is a major way that cells provide the energy to reassemble ATP. There are actually a number of ways, but one of the more effective is the “Electron Transport Chain”.

In simple terms, the cell takes an electron from a simple “food” molecule of some sort, and passes it along to a type of protein that reaches through the cell’s membrane. This protein passes the electron along to another protein, but in the process, it goes through a series of changes in shape that allows it to pump a few hydrogen ions (“protons”) from the inside of the cell’s membrane to the outside. Depending on how much energy (as “electrical potential”) was released along with the electron by the “food” molecule’s electron donation, there may be enough energy to shove the electron through up to three different proteins that do this “proton-pumping” trick with each electron.

This process causes there to be a buildup of protons outside of the cell membrane. Since the universe is lazy, it doesn’t want to hold all those crammed-together protons in place – it really wants to shove them back inside the cell so there’ll be an even concentration of them on both sides of the membrane.

The cell has a special sort of gate which lets the protons shove their way through back to the inside of the cell – but in the process, they make part of the ‘gate’ mechanism rotate. The rotating part essentially grabs ADP and loose phosphate and virtually crams them back into place – the energy to do this comes from the force of the protons shoving their way back into the cell.

But what about the electron? Well, at the end, there has to be something that will pull the electron off of the last protein. One of the best “electron acceptors” is oxygen. Oxygen is the second most electron-loving kind of atom there is. Half of an oxygen molecule (O2), a couple of spare protons, and two electrons make a nice, relaxed, stable molecule of H2O.

The reason I find this interesting is because some bacteria can use something besides oxygen, if oxygen isn’t available. They don’t get quite as much energy out of the process since these other “electron acceptors” don’t pull the electron out quite as hard at the end, but it’s better than suffocating. Sulfate-respiring bacteria, for example, can use sulfate (SO4) as the place to dump the electron, converting it to sulfite (SO3) in the process – and eventually converting it to plain “elemental” sulfur (just “S”) or even in some cases using the elemental sulfur in place of oxygen and making H2S – which is that ‘rotten-egg’ smelling gas.

There are some even more exotic “electron acceptors” that some bacteria can use…which will be the topic of another post.

(And, again, please let me know if you spot anything wrong here, and please ask questions if I’m not making any sense – I’m pretty sure I need the practice explaining this kind of thing…)

Cheap Miscellany

Tonight’s post will be a bit short, but I’ll try to make up for it tomorrow. (Three more days of Just Science week to go…)

First, a quick unsolicited plug for someone else’s site: Aetiology is doing a series of posts on “Normal Flora” – that is, the microbes that normally live on and in healthy people (as opposed to microbes that just cause disease). Since that’s an area where my own interests overlap with the more conventional “medical” microbiology, it seems appropriate to mention it here. As of right now, there is a Part 1 and a Part 2. Interesting and informative stuff.

Second, a small addendum to the previous post – I mention that I think when people say “Gram-Positive” they generally really mean Firmicutes, but I just realized there’s one exception to that. The Firmicutes actually include Mycoplasma and related bacteria – which have no cell wall at all. I would guess their ancestors were normal “Gram-Positive”-type firmicutes but somewhere along the way “lost” function of a key gene involved in making the thick cell wall. (There’s a similar group of Archaea – the Thermoplasmata. ) These don’t stain Gram-positive (and perhaps don’t stain gram-negative, either – seems like such fragile things would be destroyed by the staining procedure). In order to see these in the microscope, the standard method seems to be to use a chemical that actually stains DNA instead. Instead of staining the outer surface of the cell like most of the classical stains, this stains the inside of the bacteria (which tend to have their DNA spread more or less throughout the entire cell in one form or another, since they have no nucleus to pack it into) with a fluorescent material, which you can then see in the microscope with the right kind of light. You can also use this kind of technique for other bacteria, too. The “Live/Dead” stain I previously mentioned works this way, if I remember correctly.

Since you probably don’t want to try heat-fixing Mycoplasma, you have to use a “fixative” (a preservative made of alcohol and pure acetic acid) and then air-dry the slides.

This leads to one last correction – in a previous post I suggested that it was unlikely that you could “glue” your smear to the slide rather than heat-fix (assuming that the “glue” would interfere with the subsequent staining and viewing of the sample) – this is actually not completely correct. I heard today of a protocol for doing endospore and acid-fast stains which called for mixing the culture sample with serum on the slide to make it stick, so there are at least a few ways to “stick” cells to the slide and still look at them.

Are “Acid-Fast” bacteria Gram-positive or Gram-negative?

I was wondering what today’s post ought to be – but a Google™ search that reached the page posed an interesting question and made it easy.

Someone from a Miami, Florida college got to this site after asking Google:
“Assuming you could stain any cell, would an acid-fast [bacterium] be gram-positive or gram-negative?”

Therefore, today’s post will deal with some Microbial Physiology.

The easy answer is, of course, “no“.

A more useful answer, though, is that it depends on what you mean by “Gram-positive”.

If one takes the “Assuming you could stain any cell” part of the question to mean that you’ve done whatever it takes to get the Crystal Violet/Iodine into the cell wall, and you mean “will the cell still look purple instead of pink at the end of the Gram Stain process”, then I’m pretty sure the answer would be yes, that it would be “Gram Positive”. It actually IS possible to stain “acid-fast” bacteria with the Gram stain. The catch is that it takes 12-24 hours of staining (according to Gram’s original paper) rather than a minute or so. This still counts as Gram-positive, though, and in fact the whole Phylum of Actinobacteria (including the Mycobacterium genus) is considered “High G+C Gram-positive”. (If the query was for an exam or homework problem, this is probably the answer you’re looking for.)

On the other hand, if you mean “does the cell wall structure of an acid-fast bacterium better resemble Gram-positive or Gram-negative bacteria?”, you can make an argument that instead of a nice simple “inner membrane surrounded by a thick peptidoglycan-layer cell wall”, the “acid-fast” bacterial cell wall looks more like a complex gram-negative-type cell wall, having multiple layers, with special proteins that form channels through them to let substances in and out of the cell through the otherwise penetration-resistant outer layer, just as Gram-negative bacteria have through their outer membrane. (On yet another hand, those outer layers are tough like a gram-positive bacterium rather than fragile like a gram-negative bacterium’s outer membrane, and don’t dissolve in alcohol.)

Therefore, if you’re speaking in terms of taxonomy, and by “Gram-positive” you mean firmicutes which, as far as I know at the moment, are really the only class with the simple, officially-gram-positive-type cell wall structures and therefore are usually what is meant when someone says “Gram-positive” (someone please correct me if I’m wrong here), the obvious differences with “acid-fast” type cell walls can at least make a good argument that they are “not ‘Gram Positive’ bacteria”.

But if you put that on your homework or exam answers, don’t blame me if you get marked wrong…

I actually found a pretty nice illustration on the University of Capetown website showing the differences in cell wall structures here, which might help.

So, to summarize – Officially, they’re either “neither” or “Gram-positive”. Unofficially, you can probably argue either way. Hmmm. I should try to work in a post on bacterial taxonomy one of these days.

Actual Microbiology Post: some search queries

Before I embarass myself further trying to describe principles of Natural PhilosophyPhysics comprehensibly, I think I’ll do a post or two on things that I think I can more easily describe…

I will also remind everyone that I am merely an undergraduate, so if you happen to be speaking to a Ph.D. microbiologist and mention “some guy on the internet said…” and he or she tells you I’m full of it, I’d appreciate it if someone would tell me. (If they say “Wow, that guy’s a genius“, tell them I say “thanks” and ask if they’ve got any spare grant money or surplus equipment they could send me…)

I did some poking through the web server logs and noticed a few hits from search queries, looking for basic information about microbiology (and in particular, preparing and staining slides).

(I found it interesting that although most of the hits on this site are Mozilla Firefox, every single one of the search-engine-query hits were using Microsoft Internet Explorer. [Safari looks like it amounts to a little more than the number of MSIE hits.] Don’t know if it MEANS anything, but still interesting.)

Aside from a hit from someone looking for pictures of Gram-stained bacteria and, oddly, one person looking for information about the “No You Can’t Have (X), Not Yours” meme, here are the queries that have led to my page so far:

From somewhere in Kuwait: someone looking for “Gram (something) that stain red because”
From Toronto, Canada: “Gram Staining work”
Hopefully, I managed to explain whatever they were looking for back in my post about why the Gram Stain works.

The “Purpose of Heat-Fixing Bacteria on a Slide” query (posted about here) came from somewhere at a major technology company in Texas (and, coincidentally, today from someone at a college in Florida). And for Norfolk, Virginia (who just reached the site as I was typing this) – “Fixing” just means to keep something from moving – in this case, it means making the bacteria “stick” to the slide. Though I suspect he or she already figured that out from the previous “heat-fixing” post. On a related note, someone at a community college in Texas wanted to know “what would happen if too much heat were applied in heat-fixing”. To answer that one is (to the best of my knowledge), that it depends on how much is “too much”. Comparatively fragile bacteria like Mycobacteria would, I assume, tend to fall apart in the heat relatively easily. A bit more heat would probably fry the Gram-negative type bacteria, and a little more would finally destroy the Gram-positives (don’t quote me on this, I’m guessing here). One trick I’ve picked up is to hold the slide with my bare fingers (on the edges of the slide as far from the smear as possible) and slowly pass the slide into and out of the Bunsen burner flame until the slide gets uncomfortably hot (but stopping before it starts actually burning my fingers). That seems to do the job reasonably well.

Someone from the Fresno, California area wanted to find out how negative staining works.
A “Negative” stain is like a “negative” of a photograph – you’re staining everything BUT the bacteria on the slide (ideally). This is useful if something about the bacteria you’re looking at keeps it from being easily stained, or in particular if you want to see if the bacteria produces a capsule. If you stain the slide with India Ink, it’ll make the slide itself black, but leave a clear spot where the encapsulated (or, conceivably, any other bacteria that won’t soak up the ink) are, so you can find them. They also apparently do something similar in some kinds of electron microscopy.

Someone in New Jersey wanted to know what the purpose of “Simple Stains” were. A “Simple” stain just means you’re putting one kind of dye on the slide to color the bacteria, and you don’t really care about the color. Unlike differential stains (like the Gram stain) or a diagnostic stain (like an Endospore stain), it doesn’t really tell you anything about the bacteria other than what you can directly see in the microscope – but if the relative size, shape, and arrangement of the bacteria is all you’re interested in, a simple stain may be all you need. It doesn’t matter too much what kind of dye you use for this – I know methylene blue is a common one for this kind of thing.

Someone at a facility in Wyoming was trying to figure out what an alcohol wash did to bacterial cell walls. Presumably he got directed to this site because of my Gram Stain post. It’s probably worth mentioning that I believe the alcohol wash doesn’t actually do much to the cell wall – but it does seem to remove the outer membrane that is outside of the cell wall, if the bacteria have one.

Someone in the Chicago, Illinois area appeared to be searching for general information on choosing a dye for staining – that one probably deserves a post of its own, but I’ll try to put something together on it.

Another query was someone from the Phillipines specifically looking for an article on Schizomycetes. I just notices something about that post – I actually forgot to add one useful note about “Fission Fungi”: That’s what “Schizomycete” actually means (Greek: Schizo-: split in two -mycetes: relating to fungus). Also, for those photosynthetic bacteria (“Fission Algae”) the contemporary term was “Schizophyte”.

Finally, I find myself intensely curious about the very focussed query originating from a healthcare product company in New York, looking for information about Gram Staining of Bacillus atropheaus, specifically. Maybe Willy Bacillus has found his first fan…

The Entire Universe Explained Part 2: The Most Fundamental Observation

“The Universe is Powered by Laziness”

(I obviously need more practice – I’m still not sure how coherent this explanation is to anyone but me. Comments welcome here – or if you prefer, you can contact me via XMPP (“Jabber”, “Google Talk”) at XMPP:epicanis@enzymestew.dogphilosophy.net )

There you have it, the big secret that is at the heart of every single thing that happens in the natural world. Everything is the result of the Universe’s laziness. This is more or less what the Second Law of Thermodynamics says. In more proper language, it’s the observation that the total “disorder” in the universe is continually and unstoppably increasing.

I like to think of the universe as a big, fat, obnoxious sports fan. Picture him slouching in his couch. In one hand he’s holding a gigantic can of the most awful “lite beer” you can think of – you know, the one that only losers like – and in the other he’s got a giant foam hand with the logo of that team that only complete weenies like. He doesn’t even bother cheering – he just sits there, slouching as much as possible, maybe drooling a little, and wishing he could relax until he was nothing but an ever-spreading lump of flab…

So, what does this mean? Firstly, that there are always some “losses” whenever something happens. Basically, the universe can never manage to open a fresh can of that awful Lite Beer that it drinks without spilling at least a little bit of it on the floor. Secondly, that any bit of the universe you might happen to look at always wants to slouch a little further if it can.

That first part is what accounts for the “losses” in light of the “nothing magically disappears” observation previously mentioned. In the real world, no matter how carefully you build something, you can never quite get as much energy out of something as you put into it. You might get nearly all of it back out if you’re really careful, but no matter how carefully you hand 12 ounces of beer to the Universe, it always seems to end up with only 11.999999999 ounces of beer to drink. Or a lot less. It didn’t “disappear”, it just ended up soaked into the Universe’s filthy carpet where it is no longer available for anyone to drink. That beer-spillage is what physicists call “Entropy”. Or, “Heat no longer available to do Work“, if you want the proper physics definition.

The second part relates to the fact that there is a certain amount of “energy” inherent in the way any kind of matter is arranged. Matter, being part of the universe, is lazy, and doesn’t like having to hold onto all that energy. If you give it an opportunity, a piece of matter will tend to want to rearrange itself so that it’s not holding onto as much.

As an example, if you mix together some chemicals that will burn together if you light them, then seal them completely in a solid container, and set them off (by adding just a little bit of energy), you’ll find that the weight of the sealed container stays the same before and after…but it got really hot. That means there was energy released, and apparently a lot more than the little bit that started the whole thing – where did it come from?

The answer is that it was “built in” to the structure of the chemicals. Setting them off with a little bit of energy shoved the chemicals together just hard enough to let them recombine in a way that they didn’t have to hold on to all the energy they had up until then. All the energy the lazy chemicals let go showed up as heat. The little bit of energy you had to put in to get things started is what chemists call “activation energy”. It’s just there because those molecular slackers sure weren’t going to put out any extra effort to start rearranging – but once a couple of them are shoved together hard enough to make them get started, the energy they release is enough to shove a few more molecules together and get them to release more energy…and so on.

Because cool science types seem to avoid using whole words whenever possible, this energy that comes out is referred to as ?G. The total amount of energy that is “built in” to a particular molecule is referred to as “Gibbs’ Free Energy” (named after William Gibbs.)

So, for the last horrible analogy for now, let’s return to our big fat slob of a Universe slouching on his sofa. He’s been drinking that disgusting beer of his all night, and his bladder’s full. He’d really like to go to the bathroom but, eh, it’s too much effort to stand up. However, if you get behind him and shove hard enough to push him off of the sofa, then he figures while he’s up he might as well hit the bathroom before he sits back down. And, yes, I suppose that means it is my fault if next time you go camping, you end up waxing poetic and describing the nice, comfy campfire as “urinating heat and light on everybody”.

Microbiologically, that means that for a microbe to be able to live on some kind of “food”, it’s got to be possible to convert the food into substances with less energy built in, in such a way that it can capture and store some of the released energy in the process for its own use. It also means that if the microbe needs to make more of, say, some kind of enzyme (a more “ordered” combination of smaller molecules) it’ll have to shove in some energy to make up for the increased “order” while it assembles the parts.

Finally, what enzymes (or any other kinds of catalysts) do is reduce “activation energy” for a particular reaction, so bacteria don’t have to burst into flame in order to “burn” sugars for energy (for example).

And now I think I ought to go back to Microbiology posts before I get myself lynched by angry chemists and physicists for making a mess of this explanation…