Microbiographies detail the interesting lives, history, and fun facts of different microbes. We hope that you enjoy learning about these fascinating tiny creatures that live all around, on, and inside of us. If you are attending ASM Microbe 2017, please stop by our Symposium on June 1st. Details are available here.
Thanks to Paul-Enguerrand "Pablo" Fady from the Department of Microbiology and Immunology at McGill University (commonly known as "MIMM") for writing up these microbiograhies as part of a larger project to spread awareness about the problem of antimicrobial resistance. MIMM is an interdisciplinary department committed to excellence in teaching, research, and service in the areas of infection and immunity. Students in MIMM are afforded many opportunities to explore these areas by leveraging cutting-edge technologies to solve practical problems throughout their education. To view more of MIMM's efforts that started with our CDC Do Something About Antibiotics Challenge, please click here.
As this beautiful plushie shows, Streptomyces are filamentous bacteria, which look and act a lot like fungi when observed under a microscope. This can lead to confusion when growing a culture of these bacteria in the lab, as they are all-too-easily confused with fungal contamination!
Streptomyces are “good bacteria,” but not the kind you are most likely thinking of. Species of this genus do not make up a significant portion of the human microbiome, and so do not contribute directly to our health, but they have saved countless lives by providing an important source of antibiotics. These are the types of microbes that students taking part in SWI’s crowdsourced research hope to find in their soil samples as they are known to be strong antibiotic producers.
The list of available antibiotics produced by bacteria in this genus is far too long to reproduce here, but includes extremely common compounds such as tetracycline, chloramphenicol, and daptomycin. Next time you fall ill with a bacterial or fungal disease, you may well be treated with a derivative of a Streptomyces compound.
This plushie of Pseudomonas aeruginosa provides a perfect example for the phrase: “Never judge a book by its cover.” While it may appear deceptively cute, the organism itself is highly dangerous: it is one of the six species included in the list of “ESKAPE” pathogens. These are antibiotic-resistant hospital-acquired illnesses, which are particularly difficult to treat.
As with all bacteria, our knowledge of this species is rather incomplete, and new discoveries are being made every day. Pseudomonas aeruginosa was commonly referred to as a “soil microbe,” but has since been found to be part of the human microbiome — the communities of bacteria living in and on humans. It has also been found in water, and has even been taken to space as part of NASA experiments into the effects of spaceflight on microbes!
Back on Earth, P. aeruginosa is particularly present on human skin and in our lungs, and does not usually cause disease. However, hospital patients who need catheters or who are badly burnt are at risk of serious infection from this species. This type of microbe, which takes advantage of pre-existing immunosuppression in patients, is called an “opportunistic” microbe.
Simply being opportunistic doesn’t make P. aeruginosa a “bad bacterium,” however. As part of the human microbiome, it has also been shown to guide the immune system and promote inflammation. This tends to be perceived as “bad,” as it increases the risk of tissue damage caused by the human immune system. In reality, this means that it also helps maintain the balance in case of infection by promoting a response to clear the infection. Every cloud has a silver lining.
Humans have an extremely deep link with Lactococcus lactis. As its Latin name suggests, this species has long been exploited in the production of milk products like cheese. In fact, lawmakers in Wisconsin (the USA’s foremost cheese-producing state) were so enamored with L. lactis that they voted to make it the official state microbe in the Assembly; unfortunately, the bill was not picked up by the Senate.
This organism is used because it is particularly well adapted to “eating” lactose, a sugar found in milk, which they convert to lactic acid. The acidic environment makes soluble proteins insoluble, contributing to the formation of the clumps we know as “milk curd.” This process is commonly called “curdling” and also involves the enzyme rennet. As this bacterium and its products are entirely non-toxic (to say the least), humans regularly consume the Lactococcus lactis along with the cheese it was used to make.
However, this humble spherical bacterium is noteworthy for more than its milk-curdling properties. It was used in “the first human trial with a genetically engineered, therapeutic bacterium.” In this trial, the bacterium released IL-10, a protein, in the guts of patients with Crohn’s disease. The result: 8/10 patients saw a “clinical benefit,” with 50% of all patients treated going into complete remission.
The same experiment had been attempted, but with the protein delivered systemically (i.e. not released at a local site). The results for those experiments had shown 23.5% and 33% remission — substantially lower than when Lactococcus lactis released the protein locally! Our increasing understanding of microbiology is reshaping what is possible in biology and medicine.
Though it may look a little like an alien squid, bacteriophages (phage) like this are actually viruses that only infect bacteria and are found predominantly in seawater. In addition to their looks, their names can also sound quite alien: ΦX174, T7, and λ phage all sound like they were taken right out of a science-fiction story.
ΦX174 is a phage of particular note: many prolific biologists have made incredible strides when working with this virus. Fred Sanger (inventor of modern DNA sequencing) published the whole genome of ΦX174 40 years ago, paving the way for a new era of biology.
ΦX174, however, is a bacteriophage without a tail. This plushie looks much more like a mycobacteriophage or a λ phage. The latter is a virus discovered by a pioneer of microbiology, Esther Lederberg. Her contributions to the field, though not appropriately recognised at the time because of her being a woman, are invaluable. Her work on λ phage as well as on bacteria led to profound changes in our understanding of genetic transfer in microorganisms.
In some places outside of the United States, bacteriophages are used to fight antibiotic-resistant bacteria. This technology was largely developed in the former Soviet Republic of Georgia, originally due to a lack of access to antibiotics. In the United States, this therapy has only been permitted on rare instances as a last resort due to current FDA regulations that would make it extremely difficult to approve for general use and as it is very individualized.
Phages have already played a key role in advancing biomedical science, but their story seems far from over.
For more fun reading on phages, please click here.
Don’t let the googly eyes on this adorable microbe fool you. This is a dangerous pathogen! Klebsiella pneumoniae is one of the 6 pathogens that Small World Initiative researchers focus on — the ESKAPE pathogens. These are recognised as being the leading causes of antibiotic-resistant hospital-acquired illnesses and are particularly difficult to treat.
Klebsiella pneumoniae mainly causes pneumonia in already-ill patients. It is what is known as an “opportunistic pathogen” — a disease-causing microbe that will take advantage of any opportunity to cause infection. In this case, “opportunity” means “weakened immune defenses”; this means that Klebsiella pneumoniae affects people who are already sick with diseases such as HIV/AIDS.
In recent years, carbapenem-resistant strains of K. pneumoniae have emerged globally. Unfortunately, according to the CDC, carbapenems tend to be used as “the last line of defense against Gram-negative infections” that already exhibit resistance to other antibiotics. Without significant research into new antibiotics, carbapenem-resistant Klebsiella pneumoniae is likely to pose a major health threat in the coming years. Thankfully, SWI is part of a growing movement aimed at addressing the lack of available antibiotics and discovering new antimicrobials to treat resistant infections.
As with most bacteria, people tend to have a negative association with Streptococcus species. This is because many species in this genus are pathogenic. Many people suffer from “strep throat” infections and might only consider Streptococcus species as strictly pathogenic. In fact, nothing could be further from the truth!
One of the most prominent species of the Streptococcus genus, Streptococcus pneumoniae, is a leading cause of pneumonia. Children under the age of 5 are particularly at-risk of infection by this bacterium, yet it is found in the airways of 60% of healthy preschool children. As is the case for many bacteria, the many ways in which the species interacts with its host have yet to be fully understood.
Another example of streptococcal bacteria benefitting humans is our use of Lactococcus lactis. This species is intimately linked with human activity and is used industrially in the production of dairy products such as cheese.