Microbiology For Dummies
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Today is perhaps the best time in history to be a microbiologist! The development of new experimental techniques and ability to sequence organisms without actually culturing them in the laboratory first has revealed diversity and complexity in the microbial world not previously known.

Most microorganisms can’t be grown in the lab, so they were previously unknown before the development of DNA sequencing techniques. Exploiting this microbial biodiversity for drug discovery and biotechnology applications is an exciting area of research.

With the widespread availability of antibiotics and vaccines in the last half of the 20th century, infectious diseases were thought to be under control. The emergence of antibiotic resistance and the rapid evolution of bacterial and viral pathogens have made medical microbiology an urgent and exciting field of science.

Exciting frontiers

It’s an exciting time for microbiology because the tools available to study microbes have improved a lot recently. Molecular biology (the study of nucleic acids such as DNA and RNA) has improved so much that microbiologists are now using molecular tools in many branches of the field.

These tools include DNA and RNA sequencing and manipulation, which have allowed microbiologists to understand the function of enzymes and the evolution of microorganisms, and have allowed them to manipulate microbial genomes (the genetic material of organisms).

Complete sequencing of microbial genomes is an exciting frontier because it opens the door to knowledge about the varied metabolic diversity in the microbial world. Only a fraction of the many microorganisms on earth have had their entire genomes sequenced, but from those that have, science has learned a lot about microbial genes and evolution.

One interesting example of this is the recent sequencing of the complete genome of the strain of Yersinia pestis responsible for the Black Death plague in England that decimated the human population in the 1300s. DNA collected from excavated remains was carefully sequenced to reassemble all the bacterium’s genes and showed how this strain is related to the strains of Y. pestis still around today.

A rapidly increasing field in microbiology is the study of all the microorganisms and their genes and products from a specific environment, called microbiome research. This exciting new frontier of microbiology is possible because of advances in sequencing technology and has opened our eyes to the unseen diversity of microbial life on earth.

Recent surveys of oceans, for instance, have revealed many times more species of bacteria and archaea than expected, with untold new metabolic pathways.

A popular focus of microbiome research is on the microbes that inhabit the human body. The collection of microbes that naturally live in and on the body are present in everyone and potentially play a huge role in human health and disease.

Microbiologists think this is the case because these microbes are present in numbers greater than ten times those of the cells of the human body. They account for up to 2-1/2 pounds of the adult body weight and express around 100 times more genes than we do.

Research into the microbes of the human body and all their genes is called human microbiome research and has found links between it and everything from weight gain to cancer to depression.

Remaining challenges

Microbiology is still a young science, so there are many frontiers yet to explore. For instance, it appears that scientists have described only the tip of the iceberg for the variety of microbial life on earth. In particular, the variety of viruses that infect humans are not all known. Plus, the many varieties of viruses on earth are hard to even estimate.

The study of cures for viral diseases is still a major challenge, with viruses like HIV and influenza remaining a significant challenge. Viruses like polio and measles that have been essentially eradicated in developed countries still kill and disfigure children around the world in developing countries.

As recently as 2014, India was declared polio free, only after more than $2 billion was spent mounting a massive vaccination campaign. However, infectious diseases like pneumonia are still the number-one cause of childhood death around the world because vaccines are hard to deliver in developing countries.

Research is ongoing into protection from diseases like malaria and tuberculosis. Vaccination has not proven effective for these diseases that hide from the immune system. Other strategies against malaria include infecting mosquitos (the insects that infect humans with the disease) with bacteria that kill the malaria parasite, but research is ongoing.

Vaccines are effective for prevention of infectious disease, but it’s antibiotics that are used to effectively treat active infections. After the golden age of antibiotic discovery came a long period of reliance on antibiotics by modern medicine. They were so effective in treating most infections that doctors became complacent about their use.

Mankind is now entering the antibiotic resistance phase where most, if not all, of the antibiotics now used are becoming useless against the rise of antibiotic-resistant pathogens. This has become such a serious problem that in the spring of 2014, the World Health Organization declared antibiotic resistance a global health crisis.

About This Article

This article is from the book:

About the book authors:

Jennifer C. Stearns, PhD, is an assistant professor in the department of medicine at McMaster University. She studies how we get our gut microbiome in early life and how it can keep us healthy over time. Michael G. Surette, PhD, is a professor in the department of medicine at McMaster University, where he pushes the boundaries of microbial research.

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