"Hope he's only a Sunday creationist" by G. Trudeau

This comic strip by Garry Trudeau was published in 2006, so you may already know it. Here, a doctor offers two antibiotic choices to a patient suffering from tuberculosis (TB). The choice appears to depend on the patient's religious beliefs. I hope the patient chose wisely -- for his own benefit and for that of all the people that could be otherwise infected by his spreading of TB microbes.



Interestingly, cartoonist Garry Trudeau is the great-grandson of Dr. Edward Trudeau, who founded the Adirondack Cottage Sanitarium for the treatment of pulmonary TB, at Saranac Lake, New York State, in 1884. It was found at the time that tuberculous patients greatly benefited from a "rest cure" that included lots of mountain fresh air, and good nutrition. The sanatorium was later renamed and reorganized as a biomedical research center. Known today as the Trudeau Institute, it is devoted to researching our immune system to find better ways of preventing and treating human diseases, including TB, influenza, tropical diseases and cancer.



Credits for images:
- Cartoon:
Author: Garry Trudeau (Doonesbury.com). Source: GoComics.
- Stamp:
United States Postal Service. Stamp designed by Howard E. Paine and created by Mark Summers, based on a photograph of Dr. Trudeau provided by the American Lung Association. Source: The Stamp Collecting Round-up. See also a press release at EurekAlert.


Hat tip:
Comunicar ciencia con humor [in Spanish] by José Pardina, Asociación Española de Comunicación Científica (AECC) [Spanish Association for Science Communication].

Read the rest of the article >>>

Gene transfer in bacterial arm races

The following videos are two short documentaries made by students in the MIT Graduate Program in Science Writing. Both films refer to a recent discovery of new antibiotics by scientists at the Massachusetts Institute of Technology and the University of Florida. But, please, don't say: "bah, another antibiotic discovering, so boring". What makes this an interesting story is not the particular antibiotics themselves (we'll see if they ever become useful), but the way they were discovered. Or should we say "created"?

It's been known for some time that the genomes of many microbes contain genes putatively coding for the production of many small molecules. Some of these molecules may have antibiotic, anticancer or other potentially useful activities. By looking at the genomic DNA sequence, scientists can often predict that such a microbe has the potential to produce specific metabolites, belonging to defined structural classes (polyketides, non-ribosomal peptides, glycosides, etc.). However, very often, the predicted metabolites are not detected when the microbe is cultured under standard laboratory conditions. Why is this? The usual explanation is that these molecules are only produced under specific circumstances that the microorganism faces in its natural environment.

With this idea in mind, the above mentioned researchers tried to find antibiotics in the cultures of a bacterium called Rhodococcus fascians (let's call it "Rhodo"). Rhodo belongs to a group of bacteria known as actinomycetes, which are well-known antibiotic producers and whose genomes are rich in information coding for the synthesis of potentially useful metabolites. The scientists cultured the microorganism under a variety of conditions: they tried both standard and unusual ones (starvation, sub-optimal temperatures or culture media, etc.). However, no antibiotic activity was ever detected.

So, they tried to "stress" Rhodo by adding another microbe in the same flasks: the name of the second partner was Streptomyces padanus ("Strepto", for short). Strepto produces a potent antibiotic (actinomycin) that kills bacteria such as Rhodo. So, what was the point? Rhodo died in all flasks, didn't it? Well, not in all of them. In one particular flask (out of hundreds), Rhodo not only survived but actually exterminated Strepto! The "Super-Rhodo" did this by producing a new antibiotic substance, never seen before. Moreover, Super-Rhodo was able to do this thanks to a piece of DNA that Rhodo stole from Strepto!

Both documentaries refer to the same story, but they use remarkably different styles. Please watch both of them, and post a comment if you want to share your thoughts (about them or about the story).

The first video is War in a Petri Dish, by Grace Chua, Allyson Collins, and Lissa Harris:

Click To Play

The second video is Shot in the Dark, by Andrew Moseman, Rachel VanCott, Megan Rulison, and Ashley Yeager:

Click To Play

There are some scientific aspects that may need some clarification. The initial idea was that Rhodo contained the genetic potential to make antibiotics, and the genes responsible for this were only "switched on" under certain unknown circumstances. This might be correct, but the mentioned results don't clearly validate it. When Rhodo faced a Strepto attack, it simply died. The only survivor (and now a killer itself), Super-Rhodo, had acquired genetic material from its enemy. This extra piece of DNA was essential for production of the new compounds. Although full details have yet to be published, it is not clear if the transferred DNA contained all, or some, of the genes coding for biosynthetic enzymes for antibiotic production. The new antibiotics are not related to actinomycin; however, it is possible that Strepto is able to produce them, in addition to actinomycin (again, under certain unknown circumstances...). Alternatively, the real effect of the extra DNA might be just regulatory, coding for some factor that induced the "switching on" of Rhodo's own genes. We'll wait for the answers to these doubts.

Scholar article:
K. Kurosawa, I. Ghiviriga, T.G. Sambandan, P.A. Lessard, J.E. Barbara, C. Rha, A.J. Sinskey (2008). Rhodostreptomycins, Antibiotics Biosynthesized Following Horizontal Gene Transfer from Streptomyces padanus to Rhodococcus fascians Journal of the American Chemical Society, 130 (4), 1126-1127 DOI: 10.1021/ja077821p

Related link:
Deadly mycelia: predatory streptomycetes. Twisted Bacteria (Jan. 15, 2008).

Read the rest of the article >>>

Women scientists, sixty years ago

New York City, 1949. During the last three years, Elizabeth Hazen had been isolating hundreds of microbes from dirt samples taken at different locations. Many microbiologists at the time were following a path open by Alexander Fleming, Selman Waksman and others, who discovered that some soil microbes produced certain substances—antibiotics—with powerful activities against bacteria. However, rather than looking for a new agent against prokaryotic microbes, Elizabeth searched for a medicine to fight fungal infections. For this purpose, she grew the soil microbes and tested the cultures against disease-causing fungi (Cryptococcus neoformans, Candida albicans [see image]). Whenever a culture showed an interesting activity, she put it in a glass Mason jar and mailed it to Albany, 250-km away. Here, Rachel Brown—a chemist—used the culture for purification and characterization of the active compound. Then, Rachel mailed the fruit of her efforts back to New York, where the microbiologist tested the sample again for fungicidal potency. Through this collaboration, the two scientists isolated several antifungal compounds that, unfortunately, were too toxic when tested in laboratory animals.

But, finally, Elizabeth and Rachel found a useful fungicidal agent with a lower toxicity. It was produced by a soil bacterium isolated from a sample that Elizabeth had collected, while on holiday, in Warranton, Virginia. She had taken a bit of soil at the edge of a cow pasture, near a dairy barn, at the farm of a certain Walter B. Nourse. Because the microbe appeared to be a new species of streptomycetes, it received the name Streptomyces noursei, in honor of Mr. Nourse. The fungicidal agent was initially named fungicidin, but it was soon renamed nystatin, as both Elizabeth and Rachel worked for the New York State Department of Health (although in different locations). Since then, nystatin has been widely used to treat candidiasis and other fungal infections.


Related links:

• Elizabeht Hazen, seeker. Arts of Innovation.
• Elizabeth Hazen and Rachel Fuller Brown, Pharmaceutical Achievers. Antibiotics in Action.
• News of Science: Scientists in the News (on E. Hazen). Science (1955) 122, 914.
• Women in Microbiology, Microbes and Society: A Closer Look.
• Elizabeth Hazen Biography. World of Microbiology and Immunology.
• Elizabeth Lee Hazen and Rachel Fuller Brown. Inventor of the Week, Lemelson-MIT Program.

This post modestly celebrates March 8th, International Women's Day. The discovery of nystatin seems a good example of an important contribution of women scientists to microbiology, natural product chemistry, and medicine. A related story is that of Alma Whiffen, who discovered cycloheximide—also known as actidione—around the same time (1947). She isolated the compound from cultures of a soil microbe, Streptomyces griseus. Cycloheximide has antifungal activity, and was employed to treat fungal infections in plants; however, it is not useful for human treatment. The compound is better known as a general inhibitor of protein synthesis in eukaryotes, and it is widely used for research purposes. Read more here:

• Antibiotic for Plants. Time (Nov. 22, 1948).
• Alma Whiffen Barksdale Records. The New York Botanical Garden.

More related links:

• Microbiology pioneer dies (Esther Lederberg, discoverer of the lambda phage). Aetiology (Nov. 30, 2006).
• Committee on the Status of Women in Microbiology, American Society for Microbiology.
  
• Women in Science, the blog.
• Iraq's women scientists. BBC News, Middle East (Sept. 22, 2004). The dark side of microbiology...

Image credits: Wikipedia.

Read the rest of the article >>>

A medicine cabinet in her ears

Image: European beewolf carrying a honeybee towards its tunnel. Source: Wikipedia.

In a previous post (Intertwined lives: symbiosis), I mentioned the friendship between beewolf wasps and their pet microbes: female beewolves carry live cultures of fungicide-producing streptomycetes in specialized glands of their antennae. The insect spreads a secretion from these glands all over its underground nest, just before leaving an egg. The secretion (rich in streptomycetes) protects the beewolf offspring against fungal infections.

The symbiosis seems to be quite specific for this particular kind of wasps (Philanthus species) and the corresponding streptomycetes (‘Candidatus Streptomyces philanthi’). Other wasps do not have these bacteria, nor the special glands. Therefore, the relationship between beewolves and their microbes probably started around the time of origin of the first Philanthus. According to genetic studies made with the streptomycetes found in different beewolves (isolated from Europe, America and Africa), the time of origin dates back about 26-67 million years.

Now, how would you like to have a medicine cabinet in your ears?


Links from the University of Würzburg (Germany):

• Biology of the European beewolf (Philanthus triangulum, Hymenoptera, Crabronidae)
• Symbionts for pathogen defense – Beewolves and their antennal bacteria
• Morphology, ultrastructure and phylogeny of beewolf exocrine glands

Other links:

• Beewolf (Philanthus), at Wikipedia
• David Element's Wildlife Web Page Hymenoptera 1 - Bee Wolves

Related link (added April 17th, 2011):
Streptomyces en las antenas, antibióticos en el capullo [in Spanish] por Manuel Sánchez. Curiosidades de la Microbiología (April 17th, 2011).

Read the rest of the article >>>

Deadly Mycelia: Predatory Streptomycetes

Streptomycetes are often viewed as friendly, soil-dwelling saprophytic bacteria —feeding on dead or decaying matter. But, actually, some of them are pathogenic agents. For instance, Streptomyces scabies is responsible for the common scab of potatoes and other root crops. And some streptomycetes are able to cause human diseases called actinomycetomas, or actinomycotic mycetomas. An example is Bouffardi's white mycetoma, produced by Streptomyces somaliensis. Nevertheless, most actinomycetomas are generally caused by other, non-Streptomyces actinomycetes such as Nocardia and Actinomyces.

Despite their potential negative effects on our health or our economy, streptomycetes are mostly notable because of their ability to produce useful compounds (antibiotics, antitumor, immunosuppressive drugs...) and industrial enzymes (proteases, xylanases, cellulases...). Of course, the term "useful" can be understood only under our human point of view. Imagine that you are a soil microbe, living in close proximity to a streptomycete. You probably don't like your neighbor: it produces antibiotics and other substances that may affect your growth or even kill you and, if the worse happens, the damned streptomycete is well equipped with digestive enzymes to feed on your carcass. It is really an awful neighbor. Under your point of view, the word "saprophyte" does not make it justice at all. But, would you call it a "predator"?

A recent report, available from Nature Precedings [1] although not yet published in a peer-reviewed journal, suggests that actinomycetes, and streptomycetes in particular, are non-obligate predators of bacteria in soil. This assertion is based on the following evidences:

• Ability to grow on live bacterial cells as a sole source of nutrients.
• Prey cell lysis accompanying growth.
• Probable involvement of diffusible molecules (antibiotics, enzymes?).

The report proposes that predatory abilities are widespread within the Streptomyces genus. Previous studies described predatory activities for a few actinomycetes, including some streptomycetes [2-6]. In one of the early studies [6], Micrococcus luteus cells (the "prey") were applied to slides which were then buried in natural soil, either outdoors or in the laboratory. At different times, the slides were stained and observed microscopically, searching for natural soil predators. The M. luteus cells were attacked by two different bacteria from soil: one of them was a gram-negative one (later known as Ensifer adhaerens), while the other one was a streptomycete, which was named "strain 34". The following description derives from the microscopic observations of soil-buried slides (see picture) [6]:

"Under nutritionally poor conditions in soil, strain 34 sought out host cells [Micrococcus luteus] by extending a slender filament of mycelium. If this mycelium found host cells, it attacked them. If it did not, it lysed. Only one strand of mycelium actually connected any two packets of M. luteus cells under attack, although more than one strand could radiate from a given packet to other packets. This would appear to represent some sort of conservation of mycelium."

(Image from reference [6]. Credits: American Society for Microbiology)

Analogous observations were made with a pure culture of strain 34 (isolated from the soil-buried slides) and agar media containing M. luteus cells [6]:

"On Noble agar, strain 34 mycelium attacked M. luteus cells in a manner similar to that in soil. However, it would seem that although there was mycelial contact with the host cells, the actual mechanism of lysis was through elaboration of a soluble, diffusible lytic agent. This was inferred because on nutritionally richer media lysis of the M. luteus cells occurred at a distance beyond the limit of mycelial extension"

Therefore, it is possible that many soil actinomycetes (particularly, streptomycetes) are predators of bacteria. It may well be that streptomycetes are able to recognize some diffusible substances secreted by their possible preys. Growth of a (specialized?) filament of mycelium may be stimulated by such substances; as a result, the filament approaches the target microbe. Then, the predator secretes its own diffusible poisons (antibiotics, enzymes?) that, eventually, lyse the prey cells. The released cellular contents are now ready to be degraded and taken up by the streptomycete.

Evidently, further research is needed for a better understanding of the ecological role of actinomycetes in soil, and the natural function of antibiotics (and other secondary metabolites). Under an applied point of view, it suggests a possible way to induce the expression of "silent" gene clusters in streptomycetes and, hence, discover new secondary metabolites: by co-culturing with potential preys.


Links:

Predatory actinomycetes
[1] Streptomyces sp. as predators of bacteria. Charushila Kumbhar and Milind Watve. Available from Nature Precedings (2007).
[2] Nonobligate bacterial predation of bacteria in soil. LE Casida Jr. Microbial Ecology (1988) 15, 1-8.
[3] Gram-negative versus gram-positive (actinomycete) nonobligate bacterial predators of bacteria in soil. LR Zeph, LE Casida Jr. Appl Environ Microbiol (1986) 52, 819-823.
[4] Interaction of Agromyces ramosus with other bacteria in soil. LE Casida Jr. Appl Environ Microbiol (1983) 46, 881-888.
[5] Ensifer adhaerens predatory activity against other bacteria in soil, as monitored by indirect phage analysis. JJ Germida, LE Casida Jr. Appl Environ Microbiol (1983) 45, 1380-1388.
[6] Bacterial predators of Micrococcus luteus in soil. LE Casida Jr. Appl Environ Microbiol (1980) 39, 1035-1041.

Predatory bacteria
- Predatory Behaviors in Bacteria - Diversity and Transitions. Edouard Jurkevitch. Microbe (2007) 2, 67-73.
- Top Bug. Lori Oliwenstein. Discover Magazine (03.01.1993).
- Martin’s Microbial Menagerie. Mark O. Martin. University of Puget Sound.

Pathogenic streptomycetes
- Streptomyces: not just antibiotics. Rosemary Loria, Madhumita Joshi and Simon Moll. Microbiology Today, May 2007 - Actinobacteria.
- Streptomyces scabies. Brooke Edmunds. North Carolina State University.
- Common Scab of Potato. Michigan Potato Diseases.
- Actinomycetoma and Mycetoma. Medical Dictionary at TheFreeDictionary.
- Bouffardi's white mycetoma. MedicineWord.
- Actinomycetoma vs. Melanoma. In Tropical Diseases vs. Cosmopolitan Diseases: IX. Mycetomas. Dr. K. Salfelder & Dr. E. Sauerteig.
- Mycetoma : a review. V. Lichon, A. Khachemoune. Am J Clin Dermatol (2006) 7, 315-321.
- Mycetoma. DermNet NZ.
- Pathogenic Microbiology: Actinomycetes. University of Maryland.

Read the rest of the article >>>

Antibiotics and viruses: a natural alliance?

At the right concentration, an antibiotic may be effective enough to kill a microbe, or at least to stop its growth. But lower antibiotic concentrations may have subtler effects on microorganisms. For instance, some bacteria respond in a funny way to very low, sub-lethal amounts of those antibiotics inhibiting cell division (such as penicillins): instead of dividing, cells become longer and longer, forming filaments. In this situation, cells are stressed but alive and still growing. Now, researchers from Université Paul Sabatier-Toulouse, France, have noticed that bacterial viruses (or phages) have also adapted to these circumstances.

When infected by these viruses, filamenting cells produce more offspring phages than the "healthier" cells do. The increased production of phages seems to be the result of faster lysis (due to defects on cell wall caused by the antibiotic) and a higher phage assembly. From the point of view of a phage making its living off bacteria, filamenting cells might be a warning sign: "hey, watch out, something is going wrong, the cells may die soon, so we better sack the place while we can."

The discovery of this phenomenon (where serendipity played a part) may have implications for medicine and biotechnology. For instance, the use of a combination of antibiotics and phages might be a new effective treatment for some bacterial infections. But the findings also bring out a possible, unexpected relationship between antibiotics and phages in the natural environment. It suggests that phages may work as amplifiers of the deadly effects of antibiotics, which are naturally produced by microorganisms such as actinomycetes. Both the phage and the antibiotic producer get some benefit: the former gets an extra burst from its unhealthy, filamenting host; while the latter gets rid of bacterial rivals in the neighborhood. Here, the antibiotic- and phage-sensitive bacteria get the worst part. But it's a cruel world.

Citation:
Comeau, A.M., Tétart, F., Trojet, S.N., Prère, M., Krisch, H.M., Fox, D. (2007). Phage-Antibiotic Synergy (PAS): β-Lactam and Quinolone Antibiotics Stimulate Virulent Phage Growth. PLoS ONE, 2(8), e799. DOI: 10.1371/journal.pone.0000799

Image: The PAS effect of phage ΦMFP on Escherichia coli MFP. Disks containing the β-lactam antibiotics (indicated by “+” symbols) produced large phage plaques in their proximity.

On Sept. 19, I added the following comment at the article site:

In addition to the potential implications for medicine (i.e., antibiotics+phages combination therapy), I like the thought-provoking idea of a possible co-evolution of certain traits in antibiotic-producing microbes and in phages infecting antibiotic-sensitive bacteria. One can imagine (have a look at Figure 1) several concentric, inhibition zones surrounding the cells (or mycelia) of an antibiotic producer. Inner zones, where antibiotic concentration is deadly for different microbes (depending on their respective sensitivities). And outer zones, where the antibiotic concentration is only sub-lethal but stimulate phage production in sensitive phage-microbe couples; we might picture it as a "defensive barrier" consisting of a higher local concentration of phages, ready to attack sensitive newcomers. Given that we really don't know the antibiotic concentrations that are actually produced by microorganisms in natural environments (at least I don't know), the sub-lethal effects of secondary metabolites may be more significant than their "antibiotic" effects. Just let your imagination fly...

Read the rest of the article >>>

Streptomyces: they're twisted!

I'm back from vacation, and trying to catch up. Perhaps this is a good moment for a brief, personal overview of Streptomyces biology, summarizing some important aspects.


Although they may look like molds, Streptomyces organisms are bacteria (eubacteria). There are essential differences at the cell and molecular levels between fungi (which are eukaryotes) and bacteria (which are prokaryotes). The similarities found between streptomycetes and fungi are the result of convergent evolution, adapting to similar environments as saprophytic soil microorganisms.


Streptomyces has a complex life cycle that includes formation of spores and other cell types. Typically, a spore germinates under the right conditions to generate a vegetative or substrate mycelium. This consists of a net of branching hyphae that grow and "dig" into the substrate to reach nutrients. Remarkably, there are few partition walls in the substrate mycelium: as a result, several copies of the genome are contained in every "cell". When nutrients are scarce (or in response to other signals), some hyphae start growing away from the substrate and into the air. In the new kind of hyphae (or aerial mycelium), partition walls are more frequently formed. At the same time, the substrate mycelium suffers a process of programmed cell death and its content is reused by the growing aerial mycelium. Finally, on the distal parts of aerial hyphae, the partition process is complete and yields beautiful chains of spores. Each spore contains a single copy of the genome.

Streptomyces and their close relatives became famous thanks to their ability to produce (among other stuff):

• antibiotics (antibacterials): streptomycin, erythromycin, tetracycline, neomycin, chloramphenicol, vancomycin, gentamicin
• antifungals: nystatin, amphotericin
  
• anticancer drugs: doxorubicin, bleomycin, mitomycin
• immunosuppressants: rapamycin
• herbicides: bialaphos

The biosynthesis of these nasty compounds is carefully co-regulated with the processes of cell differentiation, starting during the transition to aerial mycelium (on agar plates) or in late exponential phase (in liquid cultures).

However, "under standard laboratory conditions", the production of these metabolites is not essential for Streptomyces: mutants lacking the ability to produce the compounds are viable and not impaired in growth. This criterion distinguishes secondary metabolism ("reactions are not essential for viability") from primary metabolism ("reactions are essential"). That's why the mentioned compounds are called secondary metabolites.

But, if these funny bugs can live without secondary metabolites, why do they produce them? What's the use for a soil bacterium to produce an anticancer drug (for instance)? Are they spending valuable resources just to make something they don't need? Sure they're not. Of course, the microorganisms have not evolved "under standard laboratory conditions". But discussing about putative functions of secondary metabolites deserves a new post.

-----------------------------------------------------------
Images:

(a) Several Streptomyces isolates growing on agar plates. (b) A close look at the colonies of Streptomyces coelicolor. Both images by Tobias Kieser, Celia Bruton and Jennifer Tenor, reproduced from Genome Biology 2002, 3:reviews1020.1-1020.4.

Life cycle of Streptomyces coelicolor, reprinted by permission from Macmillan Publishers Ltd:
Esther R. Angert. Alternatives to binary fission in bacteria. Nature Reviews Microbiology 3, 214-224 (copyright 2005).

Read the rest of the article >>>

Romans, dried figs and Streptomyces

In the year 79 AD, the Roman towns of Herculaneum and Pompeii were devastated by a terrible eruption of Mount Vesuvius. As a result, the towns were buried under many meters of volcanic ash, which left buildings, food remains and human bodies in a remarkable state of preservation. This allows to study the state of health of ancient Romans and its relationship to nutrition and other environmental conditions. For instance, analysis of human remains from Herculaneum showed lesions typically produced by tuberculosis and, especially, brucellosis. The high frequency of brucellosis has been related to the eating of contaminated cheese: Herculaneum had an important production of goat's milk and cheese. Remarkably, the study of carbonized cheese showed particles of the right size and shape, suggesting that they were bacteria of the Brucella group.

However, the Herculaneum inhabitants appeared to suffer few non-specific infections, which were common in antiquity due to poor sanitary conditions. A recent study suggests that people were protected against these infections due to consumption of dried fruits contaminated by antibiotic-producing Streptomyces!

The author of the work arrived to this conclusion through two kinds of experimental evidences:

First, examination of food remains under the microscope (both light and scanning electron) revealed the presence of virus and possible Salmonella on eggshells, and Saccharomyces in wine and bread. More important for us was the observation, under the skin of pomegranate seeds and figs, of a dense net of branching filaments resembling those of Streptomyces. These fruits were originally dried as a mode of preservation: Romans buried them in straw under a weight to achieve dehydration. This technique may explain the proliferation of Streptomyces. And we all know that Streptomycetes are prolific producers of antibiotics, right?

Second, histological study of bone samples from human remains (using a confocal microscope) showed presence of auto-fluorescence with characteristics typical of tetracycline-labeled bone occurring during life. Tetracycline antibiotics mark human bone, as it has been established for both modern and ancient humans. An example of tetracycline-labeled human bones was previously described from a cemetery in Sudanese Nubia dated 350-550 AD; in this case, a possible source of tetracycline was the grain stored in mud containers, which provided a proper environment for proliferation of Streptomyces.

I found that the paper and the whole story (mixing archeology and microbiology together) are fascinating. Of course, I'd certainly appreciate more experimental evidence concerning unequivocal identification of tetracycline in bones (could the fluorescence be due to any other molecule with similar properties but different to tetracycline?). And I wonder how common is tetracycline production among Streptomycetes. It would be very nice if the hypothesized conditions could be replicated, i.e. grow some figs and pomegranates (Roman style = "organically" produced?), and dry them using the Roman technique (ideally in the Herculaneum region). Then, try to detect tetracycline in the fruits. You can even isolate some Streptomycetes from the dried fruits, and screen the isolates for tetracycline production...

Reference:
Capasso, L. (2007). Infectious diseases and eating habits at Herculaneum (1st century AD, southern Italy). International Journal of Osteoarchaeology, 17(4), 350-357. DOI: 10.1002/oa.906

[Sadly, the author uses the word "mould" for Streptomyces, which is a bacterium, not a fungus. This mistake can still be found in medical and other technical literature]

(Image: Mosaic on a wall in the House of Neptune and Amphitrite, in Herculaneum, Italy. Source: Wikipedia)


UPDATE (September 3, 2010):
A scientific article has been published confirming the presence of tetracycline in the Nubian bones! The reference is:
Mass spectroscopic characterization of tetracycline in the skeletal remains of an ancient population from Sudanese Nubia 350–550 CE
Am. J. Phys. Anthropol. (2010) 143, 151-154.
DOI: 10.1002/ajpa.21340
(Found via Biounalm: Los antibióticos se usaban desde hace 2000 años?)


UPDATE (September 10, 2010):
See other blogs (in Spanish): Los nubios ya usaban antibióticos hace 2.000 años (Amazings.es), Una pinta de tetraciclina (Curiosidades de la Microbiología).

Read the rest of the article >>>

Time travel

You may know Google News Archive Search. I enjoy using it to search for old, historical stories. Soon I noticed that the oldest (free) stories came from the archives of Time Magazine, which are fully available for searching and reading (don't miss the covers!). Looking for articles containing the words "Streptomyces" or "actinomycete" in the complete Time archive, I got only five hits. Remarkably, they were written on 1948, 1949, 1950 and 1963. (So sad, it seems nothing related to these terms has happened in almost 50 years!)

The Time articles, which deal with the discovery of antibiotics from actinomycetes, are:

• Antibiotic for Plants (Nov. 22, 1948). Actidione, now better known as cycloheximide, a product of Streptomyces griseus.
  
• Man of the Soil (April 4, 1949). Neomycin. You may have guessed that the "man" refers to Selman Waksman, the Father of Antibiotics.
• The Healing Soil (Nov. 7, 1949). Entertaining, long article about antibiotics (actinomycin, streptomycin, etc) and Waksman*.
• New Antibiotic (Feb. 6, 1950). Terramycin (oxytetracycline), produced by Streptomyces rimosus.
• Another Whisper, Another Wait (May 31, 1963). A brief piece on the discovery of a mysterious antitumor substance from Streptomyces. The active compound was later called anthramycin.

(*) Waksman was on the cover of this issue of Time magazine.

(Concerning the discovery of streptomycin, I very much recommend an article by Veronique Mistiaen: Time, and the great healer, The Guardian, Nov. 2, 2002)

Read the rest of the article >>>