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Program Updates Issue #19 July & August, 2006 Contents: Welcome...........................................................................................................................................................................1 Probably more than you care to know about bacteria .........................................................................2 Microbial spore formation......................................................................................................................................3 Bacteria, the space colonists................................................................................................................................5 Welcome! Oh yes, it’s been an insanely busy summer. And I fell behind in sending the updates. So sorry! This summer I’ve started writing a book – finally. Many of you have asked for a printed version of the on-line text. Well, this will be better. In fact once the book is done (actually there will be 2 volumes) it will also become the new and improved totally revised website. Volume one will be ready in December, and then it’s just a matter of putting it online. Because it only deals with the first part of the course the new website will run parallel to the current one, accessible from the main menu. It’s been four years since I wrote the online text, and after several incarnations of teaching the material in the classroom I would now organize and integrate it differently. You’ll see soon. In the meantime here is more than you probably care to know about bacteria…. Enjoy your summer – it’s glorious! Heide 1 Probably more than you care to know about bacteria! Posting to the US Composting Council Discussion Forum Post by: [email protected] May 3, 2006 Source: http://mailman.cloudnet.com/pipermail/compost/2006-May/014025.html Dear Sludge Students, My colleagues have got me thinking about the long life of bacteria and the role of sewage treatment in conferring and spreading antibiotic resistant traits. This is a fascinating business...looking at how microbes react in the stressful conditions of a sewage treatment plant, and how they react to stressors like the chlorine, detergents, metals, and antibiotics flushed to the sewers and digested in the sewage treatment plant. Clearly those microbes that are sensitive to antibiotics and antimicrobials will die off. The more resistant strains of microbes will survive and reproduce. As conditions get more stressful and food more scarce some will form spores, and will desiccate if left out to dry. In Southern Ontario the epidemic of Methicillin-resistant Staphylococcus aureus took off in 1996. - See graph - http://microbiology.mtsinai.on.ca/data/images/qmp-ls01.gif This is the same year that a massive land application program of Ontario's city sewage sludges was initiated. The Great Lakes protection legislation required sewage treatment plants on the Great Lakes to have secondary digestion by the year 1995. The secondary digester sludge was mixed with the primary sludges and this diluted the heavy metals from our urban sewers sufficiently to meet Provincial Guidelines for land application for most muncipal sludges (the 1996 Guideline for the Use of Biosolids and Other Wastes on Agricultural Lands). But while we know that "Class B" sludges containing as much as or more than 2 million fecal coliform per gram are allowed to be spread on farmland in the USA and Canada, it may also be that the further treated sludges ..so called 'Class A'...that are supposed to have less than 1,000 fecal coliform per gram, may be carrying very high loads of viable but non-culturable bacteria spores (with antibiotic resistance) that subsequently rehydrate into viable micro-organisms once land applied where the conditions are favorable. Given that virtually all hospital fecal waste, and virtually all the used and unused antibiotics (even the special reserved ones like vancomycin...the antibiotic of last resort) are disposed of into the toilets of our homes and hospitals and then digested together with all our urban sewage...doesn't it make sense to investigate the role of sewage treatment plants and the land application of sewage sludge in regard to this epidemic of antibiotic resistant diseases that are now ravaging our communities? The sludge we land apply is full of the microbes and spores of organisms that have developed antibiotic resistance in our sewage treatment plants. These micro-organisms can then flourish once they are rehydrated in a growth medium on a farm field. If we were setting about to farm and produce antibiotic resistant organisms and distribute 2 them throughout our communties and into the food chain we couldn't do a better job of it than in this institutionalized production and dispersion of sludge. Microbial Spore Formation Spore forming inside a bacterium Stahly, MicrobeLibrary Source: http://www.microbe.org/microbes/spores.asp You may have read elsewhere in this site that bacteria sometimes form protective spores to help them survive through tough times. Some other kinds of microbes do, too. Here's how that transformation takes place. First off, you might think of a bacterial spore roughly as a mummified bacterium. The spore has a hard protective coating that encases the key parts of the bacterium—think Spore forming inside a bacterium of this coating as the sarcophagus that protects a mummy. Stahly, MicrobeLibrary The spore also has layers of protective membranes, sort of like the wrappings around a mummy. Within these membranes and the hard coating, the dormant bacterium is able to survive for weeks, even years, through drought, heat and even radiation. When conditions become more favorable again—when there’s more water or more food available—the bacterium "comes to life" again, transforming from a spore back to a cell. Some bacterial spores have possibly been revived after they lay underground for more than 250 million years! Ok, so how do bacteria turn themselves into spores? First, the bacterium senses that its home or habitat is turning bad: food is becoming scarce or water is disappearing or the temperature is rising to uncomfortable levels. So it makes a copy of its chromosome, the string of DNA that carries all its genes. Then, the rubbery cell membrane that surrounds the bacterial cell fluid begins pinching inward around this chromosome copy, until there’s a little cell within the larger bacterial cell. This little cell is called the "daughter cell" and the bigger, original one, what starts out as the "vegetative cell" in this illustration, is now called the "mother cell." Next, the membrane of the mother cell surrounds and swallows up the smaller cell, so that now two Merkel, MicrobeLibrary membrane layers surround the daughter cell. Between these two membranes a thick wall forms made out of stuff called peptidoglycan <pep-tid-oh-gly-can>, the same stuff found in bacteria’s rigid cell walls. Finally, a 3 tough outer coating made up of a bunch of proteins forms around all this, closing off the entire daughter cell, which is now a spore. As the mother cell withers away or gets blasted by all kinds of environmental damage, the spore lies dormant, enduring it all, just waiting for things to get better. Not all bacteria can form spores. But several types that live in the soil can. Bacteria in the Bacillus <buh-sill-us> and Clostridium <clah-strih-dee-um> groups are spore-formers. Their spores are called endospores. Another group of bacteria called Methylosinus <meth-ill-oh-sigh-nus> produces spores called exospores. The difference between endospores and exospores is mainly in how they form. Endospores form inside the original bacterial cell, as described above. Exospores form outside by growing or budding out from one end of the cell. Exospores also don’t have all the same building blocks as endospores, but they’re similarly durable. Members of the Azotobacter <ay-zoh-toe-back-ter>, Bdellovibrio <dell-oh-vih-bree-oh>, Myxococcus <mix-oh-cah-cuss> and Cyanobacteria <sigh-an-oh-back-teer-ee-uh> groups form protective structures called cysts <cists>. Cysts are thick-walled structures that, like spores, protect bacteria from harm, but they’re somewhat less durable than endospores and exospores. Bacteria aren’t the only microbes that can form protective spores, however. Some protists can, too. For example, a group of parasitic protozoa called Microsporidia <mike-row-spore-ihdee-uh> encase themselves in protective spores when they infect their hosts. Microsporidia are found mainly in the guts of insects and the skin and muscles of fish, although a few species can cause illness in people. Microsporidia spores are usually round, oval or rod-shaped, although many species have elaborately shaped spores that may help hide them from their host immune systems. The spores help the protozoa survive while outside of a host’s body. Typically, hosts are infected when they Microsporidium spore with tube swallow Microsporidia spores. Once the spores reach the gut, they poke a tube through their spore coats. This tube thrust into host cells Courtesy of stabs through the host’s gut wall and other tissues. Then CDC the Microsporidia cell fluid and nucleus—a cell's central command center—move through the hollow tube from the spore into the host cells. As Microsporidia reproduce in the host cells, new spores are formed that are typically passed out of the body with feces. Note: The spores we’re talking about on this page are protective spores. A group of bacteria called Actinomycetes <ack-tin-oh-my-see-tees> and many kinds of fungi produce seed-like structures during reproduction that are also called spores. If you’ve ever stomped on a puffball mushroom, the brown cloud that jets out is a cloud of these reproductive spores. Like seeds, reproductive spores have tough outer coatings on them, but they aren’t as durable as protective spores or cysts. 4 What’s New? Bacteria: The Space Colonists Source: http://www.panspermia.org/bacteria.htm I always thought the most significant thing that we ever found on the whole goddamn Moon was that little bacteria who came back and lived and nobody ever said shit about it. — Pete Conrad (1) On April 20, 1967, the unmanned lunar lander Surveyor 3 landed near Oceanus Procellarum on the surface of the moon. One of the things aboard was a television camera. Two-and-a-half years later, on November 20, 1969, Apollo 12 astronauts Pete Conrad and Alan L. Bean recovered the camera. When NASA scientists examined it back on Earth they were surprised to find specimens of Streptococcus mitis that were still alive. Because of the precautions the astronauts had taken, NASA could be sure that the germs were inside the camera when it was retrieved, so they must have been there before the Surveyor 3 was launched. These bacteria had survived for Conrad 31 months in the vacuum of the moon's atmosphere. Perhaps NASA shouldn't have been surprised, because there are other bacteria that thrive under nearvacuum pressure on the earth today. Anyway, we now know that the vacuum of space is not a fatal problem for bacteria. What about the low temperature and the possible lack of liquid water in space? The bacteria that survived on the moon suffered huge monthly temperature swings and the complete lack of water. Freezing and drying, in the presence of the right protectants, are actually two ways normal bacteria can enter a state of suspended animation. And interestingly, if the right protectants aren't supplied originally, the bacteria that die first supply them for the benefit of the surviving ones! English microbiologist John Postgate discusses this fact in The Outer Reaches of Life (2): "When a population of bacteria dries out without a protectant, many of the cells break open and release their internal contents. Among these contents are proteins, gums and sugars, all of which are protective. If the population is sufficiently dense, so that significant amounts of protectant are released, material released from the majority which died first can protect a few of their surviving fellows. "Comparable considerations apply to death from freezing.... Protective substances such as glycerol are well known and widely used; they are called cryoprotectants. Bacteria frozen without such chemicals leak internal contents, among which are many substances that are cryoprotective." Postgate says that bacteria have apparently survived for 4,800 years in the brickwork of Peruvian pyramids, and maybe even 300 million years in coal, using the drying strategy. He also describes bacteria that apparently survived for 11,000 years in the gut of a well-preserved mastodon, although in this case the colony may have continued to live and multiply using nutrients available in the carcass. Postgate gives several other examples of long-surviving bacteria, and he is careful to mention the possibility that some of the bacterial cultures may have been contaminated, so not all of the reports are necessarily reliable. 5 Some bacteria have another even more effective survival strategy: they form spores. Spores are bacterial cells in complete dormancy, with thick protective coats. In terms of our computer analogy, a bacterial spore is like a handheld calculator that has repackaged itself into its original protective shipping carton and turned itself off. "The resistance of some bacterial cells to environmental destruction is impressive. Some bacteria form resistant cells called endospores. The original cell replicates its chromosome, and one copy becomes surrounded by a durable wall. The outer cell disintegrates, but the endospore it contains survives all sorts of trauma, including lack of nutrients and water, extreme heat or cold, and most poisons. Unfortunately, boiling water is not hot enough to kill most endospores in a reasonable length of time.... Endospores may remain dormant for centuries" (3). Postgate concludes his chapter on spores, entitled "Immortality and the Big Sleep," by saying, "There may be much older spores out there, waiting for energetic microbiologists to revive them." Thirty Million-Year Sleep: Germ Is Declared Alive! There were much older spores waiting to be revived. On May 19, 1995, The New York Times carried a front-page story about them (4). Biologists Raul Cano and Monica Borucki had extracted bacterial spores from bees preserved in amber in Costa Rica. Amber is tree-sap that hardens and persists as a fossil. This amber had entrapped some bees and then hardened between 25 and 40 million years ago. Bacteria living in the bees' digestive tracts had recognized a problem Ancient bee in amber and turned themselves into spores. When placed in a suitable culture, the spores came right back to life. As a control, the two biologists also attempted to culture from the same amber a number of samples that contained no bee parts. These cultures were negative, adding credibility to the experiment. This finding was originally reported in the journal Science (5) to general acceptance. Postgate, upon learning of this discovery, wrote an article for The Times of London that concluded as follows (6): "... could life on this planet be descended from alien spores? ...Panspermia, the view that the seed of life is diffused throughout the universe, has been favored by a minority of thinkers since the Greek Anaxagoras in the 5th century BC. He, Arrhenius and Fred Hoyle may yet have the laugh on us doubters." When the first bacteria colonized the earth, almost four billion years ago, it was by our standards a hostile place. There was no free oxygen to breathe and no ozone to block out the sun's damaging ultraviolet radiation. Nuclear radiation came from decaying U235, which was about fifty times more abundant then than now (7). The air was hot and full 6 Revived bacteria of noxious chemicals such as sulphurous gases released by volcanoes. Not for nothing is it called the Hadean Eon. However, there are bacteria which can live, even thrive, in a very wide variety of conditions that seem unfriendly to us (8). "Life manages very well without oxygen, evolving into flourishing communities of anaerobes. Acidity... presents no problem, as sulphur bacteria and their co-habitants illustrate, nor does a considerable degree of alkalinity bother alkophiles.... Water purity is a trivial matter: saturated salt brines support abundant bacterial life. And pressure is quite irrelevant, with bacteria growing happily in a near vacuum or at the huge hydrostatic pressure of deep ocean trenches. Temperature, too, presents little problem: boiling hot springs support bacterial life, and bacteria have been found growing at 112 C in superheated geothermal water under hydrostatic pressure; conversely, other types of bacteria thrive at well below zero, provided the water is salty enough not to freeze. And even if they do get frozen, many bacteria revive when their habitat thaws. Even organic food is not a prerequisite...." There are bacteria that metabolize iron, nitrogen, sulphur, and other inorganic materials. There are bacteria today that can live without sunlight. Archaebacteria that can withstand extreme heat have been found thriving in oil reservoirs a mile underground (9). Some species of cyanobacteria are highly resistant to ultraviolet radiation. The only thing absolutely essential for bacteria to live, grow, and multiply is liquid water. We are confident that the early Earth had plenty of water. Scientists believe that concentration of water in the earliest atmosphere for which they have data, over four billion years ago, was far higher than it is today. Bacteria have the ability to colonize an unfriendly planet like the Hadean Earth. Not just had the ability but have the ability. These are not make believe stories. All of the bacteria we have considered, with all of their unusual abilities to survive extreme environments, are alive today! What'sNEW You could take E. coli and rapidly cool it to 10° K and leave it for 10 billion years and then put it back in glucose, and I suspect you would have 99 percent survival — Leslie Orgel (10) BE SURE TO CHECK OUT THE REFERENCES ON THE SOURCE WEBSITE!!! 7