130 posts · 117,004 views
On Small Things Considered we share our appreciation for the width and depth of microbial activities on this planet. We enjoy writing about unusual and unexpected phenomena in the microbial world. Fortunately, these come our way with great frequency. We rely on contributors with all levels of experience, from undergraduate and graduate students to distinguished microbiologists. Our "Teachers’ Corner" facilitates the use of the blog in the classroom. Some of our blog’s idiosyncratic features include our "Talmudic Questions" (queries that cannot be answered by simply looking them up with Google), "Of Terms in Biology," and our "Fine Reading" posts, each of which features an exceptional research paper. Small Things Considered is sponsored by the American Society for Microbiology.
Elio Schaechter
13 posts
Merry Youle
2 posts
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- May 7, 2013
- 08:15 AM
- 28 views
No Bacterium Is An Island
by Moselio Schaechter in Small Things Considered
To paraphrase an old adage, no bacterium is an island. Indeed, bacteria in nature exist as polymicrobial communities where interactions between individuals influence activities of the entire population. This is especially true of pathogenic bacteria, although it has been mostly ignored because we frequently isolate a single species from an infection site and prescribe antibiotic therapy based upon this information. A recent paper by Korgaonkar and coworkers highlights that this practice is somew........ Read more »
Korgaonkar A, Trivedi U, Rumbaugh KP, & Whiteley M. (2013) Community surveillance enhances Pseudomonas aeruginosa virulence during polymicrobial infection. Proceedings of the National Academy of Sciences of the United States of America, 110(3), 1059-64. PMID: 23277552
- May 6, 2013
- 08:21 AM
- 14 views
The Art of Microbial Alchemy
by Moselio Schaechter in Small Things Considered
In 2001, Kashefi and collaborators published an article in Applied and Environmental Microbiology reporting the surprising finding that several iron-reducing microbes can use gold as an electron acceptor for their respiration. These microbial alchemists included both mesophilic and thermophilic bacteria as well as hyperthermophilic archaea. The beauty of this process is that the oxidized form of gold provided to the microbes, Au(III), is soluble, whereas its reduced form, Au(0), is insoluble. He........ Read more »
Kashefi K, Tor JM, Nevin KP, & Lovley DR. (2001) Reductive precipitation of gold by dissimilatory Fe(III)-reducing bacteria and archaea. Applied and environmental microbiology, 67(7), 3275-9. PMID: 11425752
- May 6, 2013
- 08:20 AM
- 20 views
A Good Defense Is Worth Stealing
by Moselio Schaechter in Small Things Considered
One widely-used tactic for defense against phage and other mobile genetic elements is to deploy a CRISPR-Cas system (click here and here) to recognize and chop them into pieces. Based on sequenced genomes, 60% of Bacteria and 90% of Archaea have the wherewithal to dispatch invaders this way. But phages also have to protect themselves against enemies, including other mobile elements. Knowing a good thing when they see it—and they have seen it from the receiving end often—some phages have stol........ Read more »
Seed KD, Lazinski DW, Calderwood SB, & Camilli A. (2013) A bacteriophage encodes its own CRISPR/Cas adaptive response to evade host innate immunity. Nature, 494(7438), 489-91. PMID: 23446421
- April 30, 2013
- 10:11 AM
- 21 views
Whose Planet Is It Anyway?
by Moselio Schaechter in Small Things Considered
This is the title my friend Fred Neidhardt recently used for a talk, and a good question it is. I suppose that most microbiologists and the readers of this blog would split the answer down the middle, the biomass of this planet and the chemical transactions therein being about half microbial, half everything else. However, it’s safe to say that most people, many scientists included, are unaware of the colossal importance of the microbial half, not only in biology and medicine but in geology, m........ Read more »
McFall-Ngai, M., Hadfield, M., Bosch, T., Carey, H., Domazet-Loso, T., Douglas, A., Dubilier, N., Eberl, G., Fukami, T., Gilbert, S.... (2013) Animals in a bacterial world, a new imperative for the life sciences. Proceedings of the National Academy of Sciences, 110(9), 3229-3236. DOI: 10.1073/pnas.1218525110
- April 30, 2013
- 10:10 AM
- 21 views
E. coli Cells Face FACS and Get Back into Shape
by Moselio Schaechter in Small Things Considered
There’s no question that variation in size and shape has conferred selective advantages over the course of evolutionary time. One of the most obvious examples are the long neck and legs of the giraffe, which allow it to snatch foliage that is unreachable by vertically challenged competitors. The variable beak shapes and sizes of Darwin’s finches represent the diverse tool set that evolved when only certain food sources became available. And the appearance of the opposable thumb, a simple cha........ Read more »
Laubacher ME, Melquist AL, Chandramohan L, & Young KD. (2013) Cell sorting enriches Escherichia coli mutants that rely on peptidoglycan endopeptidases to suppress highly aberrant morphologies. Journal of bacteriology, 195(4), 855-66. PMID: 23243305
- April 18, 2013
- 07:49 AM
- 13 views
Holey Biofilm!
by Moselio Schaechter in Small Things Considered
As a child, I was always fascinated by the holes (or eyes) in Swiss cheese, always inspecting the tunneling system before getting a good bite. Although the holes are the result of microbial activity (the accumulation of CO2 released by fermentative bacteria), I bring up the Swiss cheese analogy for very different reasons. Try to picture a similar landscape of tunnels and holes in a bacterial biofilm. And that’s what today’s story is about … a ‘holey’ biofilm.
In a recent study publish........ Read more »
Houry A, Gohar M, Deschamps J, Tischenko E, Aymerich S, Gruss A, & Briandet R. (2012) Bacterial swimmers that infiltrate and take over the biofilm matrix. Proceedings of the National Academy of Sciences of the United States of America, 109(32), 13088-93. PMID: 22773813
- February 26, 2013
- 12:41 PM
- 82 views
Bacterial Antidepressants: Avoiding Stationary Phase Stress
by Moselio Schaechter in Small Things Considered
High on the list of the exciting manners bacteria communicate with one another is quorum sensing (QS), a population-dependent gene regulation system that operates within a wide range of species. The general scheme of QS is as follows: at high population densities, signal molecules called autoinducers reach threshold levels, at which point they initiate a signal transduction pathway leading to transcription of specific genes. This altered gene expression allows the bacterial community to behave i........ Read more »
Goo E, Majerczyk CD, An JH, Chandler JR, Seo YS, Ham H, Lim JY, Kim H, Lee B, Jang MS.... (2012) Bacterial quorum sensing, cooperativity, and anticipation of stationary-phase stress. Proceedings of the National Academy of Sciences of the United States of America, 109(48), 19775-80. PMID: 23150539
- February 14, 2013
- 07:00 AM
- 107 views
The Gender Bias of Science Faculty
by Moselio Schaechter in Small Things Considered
If you were a science professor, and you received two equally strong applications for the position of laboratory manager, one from a female, one from a male, which one would you pick? The answer may surprise you.... Read more »
Moss-Racusin CA, Dovidio JF, Brescoll VL, Graham MJ, & Handelsman J. (2012) Science faculty's subtle gender biases favor male students. Proceedings of the National Academy of Sciences of the United States of America, 109(41), 16474-9. PMID: 22988126
- February 5, 2013
- 04:02 PM
- 68 views
Domestic Just for the Sake of it – The Evolution of a Fungus with Good Taste
by Moselio Schaechter in Small Things Considered
We know quite a bit about how the wild aurochs or their ilk evolved into tame, bossy cows and how the insignificant grass teosinte became nutritious maize, but what do we know about the evolution of microbes involved in food and drink production? For thousands of years before the advent of microbiology, our ancestors used microbes for this purpose without knowledge of the contributions or the domestic origins of these small workhorses. Even today, when microbes continue in key roles during food ........ Read more »
Gibbons JG, Salichos L, Slot JC, Rinker DC, McGary KL, King JG, Klich MA, Tabb DL, McDonald WH, & Rokas A. (2012) The evolutionary imprint of domestication on genome variation and function of the filamentous fungus Aspergillus oryzae. Current biology : CB, 22(15), 1403-9. PMID: 22795693
- January 21, 2013
- 07:00 AM
- 107 views
Biting the Hand That Clothes You
by Moselio Schaechter in Small Things Considered
Troublesome strains of Staphylococcus aureus are often troublesome because they carry genes for superantigens and multiple antibiotic resistance. But don’t blame the bacteria. These genes are hitchhikers that arrived by horizontal gene transfer, embedded within mobile pathogenicity islands known as SaPIs. SaPIs are common; all S. aureus strains investigated so far carry at least one. They have also been found in other staph species and a few other Gram-positive genera. They have garnered much ........ Read more »
Ram G, Chen J, Kumar K, Ross HF, Ubeda C, Damle PK, Lane KD, Penadés JR, Christie GE, & Novick RP. (2012) Staphylococcal pathogenicity island interference with helper phage reproduction is a paradigm of molecular parasitism. Proceedings of the National Academy of Sciences of the United States of America, 109(40), 16300-5. PMID: 22991467
- January 15, 2013
- 04:46 PM
- 101 views
Wolbachia Make Fruit Flies Lay More Eggs to Make More Wolbachia
by Moselio Schaechter in Small Things Considered
If you would like to have a particularly striking organism named after you, choose your collaborator well. The Harvard rickettsiologist S. Burt Wolbach was lucky to have such a colleague—the entomologist Marshall Hertig. In 1936, Hertig gave the name Wolbachia to the endosymbionts of mosquitoes they had jointly discovered in 1924. As is now widely known, Wolbachia are among the most common host-associated bacteria, infecting perhaps 70% of all insects, many spiders, and some worms to boot. And........ Read more »
Fast EM, Toomey ME, Panaram K, Desjardins D, Kolaczyk ED, & Frydman HM. (2011) Wolbachia enhance Drosophila stem cell proliferation and target the germline stem cell niche. Science (New York, N.Y.), 334(6058), 990-2. PMID: 22021671
- January 7, 2013
- 04:00 AM
- 98 views
Living Wires of the Ocean Floor
by Gemma Reguera in Small Things Considered
In a recent post I shared with you how different microbes come together to breathe as one. In some cases, all it takes is the presence of conductive minerals such as magnetite to facilitate the exchange of metabolic electrons between two microbial partners. This allows the team to catalyze a redox reaction (for example, acetate oxidation coupled to nitrate reduction) that each organism could not have been able to achieve individually. The role of conductive minerals in such interspecies electron........ Read more »
Pfeffer C, Larsen S, Song J, Dong M, Besenbacher F, Meyer RL, Kjeldsen KU, Schreiber L, Gorby YA, El-Naggar MY.... (2012) Filamentous bacteria transport electrons over centimetre distances. Nature, 491(7423), 218-21. PMID: 23103872
Nielsen LP, Risgaard-Petersen N, Fossing H, Christensen PB, & Sayama M. (2010) Electric currents couple spatially separated biogeochemical processes in marine sediment. Nature, 463(7284), 1071-4. PMID: 20182510
- December 10, 2012
- 07:00 AM
- 122 views
Love At First Zap
by Moselio Schaechter in Small Things Considered
Although both cooperation and conflict are decisive forces in evolution, some of the most successful microbial strategies for survival have arisen from cooperation. At times, two or more microorganisms can even come together to breathe as one. Breathing, or respiration, accomplishes a most challenging fête: the disposal of electrons generated in metabolic cellular reactions to gain energy for growth. The electron donors and acceptors that microorganisms can use for respiration can be aligned h........ Read more »
Kato S, Hashimoto K, & Watanabe K. (2012) Microbial interspecies electron transfer via electric currents through conductive minerals. Proceedings of the National Academy of Sciences of the United States of America, 109(25), 10042-6. PMID: 22665802
- July 30, 2012
- 07:00 AM
- 786 views
The Rise of Genomic Superspreaders
by Moselio Schaechter in Small Things Considered
by Steven Quistad
One hundred million years ago the earth’s climate was much warmer than today and vast inland seas stretched across entire continents. The land was dominated by charismatic megafauna that would one day serve as inspiration for Sir Arthur Conan Doyle’s novel The Lost World. This period is commonly referred to as the age of reptiles as our placental ancestors were barely visible. Yet it was during this period that something significant happened to them, something that would b........ Read more »
Magiorkinis G, Gifford RJ, Katzourakis A, De Ranter J, & Belshaw R. (2012) Env-less endogenous retroviruses are genomic superspreaders. Proceedings of the National Academy of Sciences of the United States of America, 109(19), 7385-90. PMID: 22529376
- July 23, 2012
- 01:00 PM
- 609 views
An Evolutionary Tale of Zombie Ants and Fungal Villains & Knights
by Moselio Schaechter in Small Things Considered
by Gemma Reguera
In a recent post I shared with you some amazing things I had learnt about coprophilous (‘dung-loving’) fungi that spit their spores like pros. What I did not tell you then is that my six-year-old son also fell in love with the spitting fungi (dung + spit = child’s interest!) and wanted to learn more. So we spent hours watching online videos until we stumbled upon a BBC’s Planet Earth video narrated by the great David Attenborough about ant parasitic fungi in the genus C........ Read more »
Pontoppidan MB, Himaman W, Hywel-Jones NL, Boomsma JJ, & Hughes DP. (2009) Graveyards on the move: the spatio-temporal distribution of dead ophiocordyceps-infected ants. PloS one, 4(3). PMID: 19279680
Andersen SB, Ferrari M, Evans HC, Elliot SL, Boomsma JJ, & Hughes DP. (2012) Disease dynamics in a specialized parasite of ant societies. PloS one, 7(5). PMID: 22567151
- July 9, 2012
- 05:12 PM
- 493 views
Fishing With Algae For Malaria Vaccines
by Moselio Schaechter in Small Things Considered
by James Gregory
Malaria is a big killer and a major worldwide health concern. The number of malaria-related deaths has fallen to approximately 650,000 in 2010, from well over 1 million just ten years ago, thanks to the World Health Organization (WHO) and to philanthropic organizations, including the Bill and Melinda Gates Foundation. This effort, composed of drug-based treatment and insecticide-treated bed nets (ITNs), was nothing short of heroic, but unfortunately it is not sustainable. Mal........ Read more »
Gregory JA, Li F, Tomosada LM, Cox CJ, Topol AB, Vinetz JM, & Mayfield S. (2012) Algae-produced pfs25 elicits antibodies that inhibit malaria transmission. PloS one, 7(5). PMID: 22615931
- July 2, 2012
- 03:13 PM
- 238 views
Oddly Microbial: 86 Million Year-Old Deep Seabed Mystery Cells
by Moselio Schaechter in Small Things Considered
by Marcia Stone
Life in a high-pressured environment with practically nothing to eat might be ok for high-fashion models, but it’s an unlikely lifestyle choice for a single cell whose usual overriding goal is to become two cells. Yet the largest living ecosystem on Earth—the deep biosphere—is comprised of microbes so energy starved that the average cell divides only once every thousand or even several thousand years.
Even what these cells are is unclear because they are so different........ Read more »
Røy H, Kallmeyer J, Adhikari RR, Pockalny R, Jørgensen BB, & D'Hondt S. (2012) Aerobic microbial respiration in 86-million-year-old deep-sea red clay. Science (New York, N.Y.), 336(6083), 922-5. PMID: 22605778
- June 18, 2012
- 01:00 PM
- 271 views
How an Endosymbiont Earns Tenure
by Moselio Schaechter in Small Things Considered
by S. Marvin Friedman
Plastids and mitochondria are organelles in eukaryotic cells that originated from bacterial endosymbionts via invasion or enslavement or a synergistic amalgamation, depending on your viewpoint. Since these events occurred more than one billion years ago, it has not been possible to trace the evolutionary steps in the transition from endosymbiont to mature organelle, a process referred to as organellogenesis. Enter the protozoan amoeba, Paulinella chromatophora. This pro........ Read more »
Nowack EC, & Grossman AR. (2012) Trafficking of protein into the recently established photosynthetic organelles of Paulinella chromatophora. Proceedings of the National Academy of Sciences of the United States of America, 109(14), 5340-5. PMID: 22371600
- May 31, 2012
- 12:35 AM
- 747 views
Are Phages the Answer?
by Moselio Schaechter in Small Things Considered
by S. Marvin Friedman
The emergence of multiple drug-resistant bacterial strains, the prevalence of recalcitrant biofilm configurations, and the reluctance of the pharmaceutical industry to initiate new antibiotic discovery programs have led to the development of a formidable population of bacterial pathogens that is increasingly difficult to control. After a long but successful era of research that had all but eliminated serious threats from bacterial infections, we are now facing this dire pr........ Read more »
Alemayehu D, Casey PG, McAuliffe O, Guinane CM, Martin JG, Shanahan F, Coffey A, Ross RP, & Hill C. (2012) Bacteriophages φMR299-2 and φNH-4 can eliminate Pseudomonas aeruginosa in the murine lung and on cystic fibrosis lung airway cells. mBio, 3(2). PMID: 22396480
Paul VD, Sundarrajan S, Rajagopalan SS, Hariharan S, Kempashanaiah N, Padmanabhan S, Sriram B, & Ramachandran J. (2011) Lysis-deficient phages as novel therapeutic agents for controlling bacterial infection. BMC microbiology, 195. PMID: 21880144
- May 28, 2012
- 01:00 PM
- 590 views
Cell Division Through DNA Curtains
by Moselio Schaechter in Small Things Considered
by Gemma Reguera
Despite the apparent simplicity of bacterial cells, their cell division cycle is a complex developmental program that couples cellular growth to the replication and segregation of chromosomes and the division of the cell’s cytoplasm (aka cytokinesis) (Fig. 1). The bacterial cell division cycle starts with the commitment of the cell to reproduce. This is the step in which, forgive the pun, size truly matters. During active growth, the cell’s size changes to accommodate in........ Read more »
Lee JY, Finkelstein IJ, Crozat E, Sherratt DJ, & Greene EC. (2012) Single-molecule imaging of DNA curtains reveals mechanisms of KOPS sequence targeting by the DNA translocase FtsK. Proceedings of the National Academy of Sciences of the United States of America, 109(17), 6531-6. PMID: 22493241
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