host-microbe interaction

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A Case of the Missing Microbes

Most animals depend on their gut microbes for digestive help. The caterpillar, however, seems to lack resident gut microbes all together.

By characterizing the microbial composition across 124 species of caterpillars from North America and Costa Rica, Tobin Hammer and colleagues at the University of Colorado Boulder found that caterpillars do not have microbial friends living in their gut. Fecal material from the caterpillars contained several orders of magnitude fewer microbes compared to other organisms. (more…)

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A Bacterium You Can See With the Naked Eye

It is commonly believed that bacteria are microscopic – stealthy and hidden from the naked eye. But the bacterium, Epulopiscium fishelsoni, is a microbial behemoth you can see with the human eye alone. First discovered in the intestines of a brown surgeonfish in the Red Sea in 1985, this giant bacterium was first classified as a protist because of its large size. In 1993, rRNA sequencing revealed that this organism is actually a bacterium.

Epulopiscium varies between 10- to 20-fold in length and has a volume more than 2,000 times that of a typical bacterium. They range from 200 - 700 microns in length, about the size of a grain of table salt. But being big does have its downsides. (more…)

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Think again before you compost that

Spring has arrived, gardens are planted, and now, we eagerly await the harvest of fruits and vegetables. This spring awakening brings not only new plant life, but fungi also come out to feast. Phytophthora root rot is a common fungal disease in plants, infecting over 250 plant genera including peppers, tomatoes, berries, and eggplants. At least a hundred species of fungi are responsible for phytophthora root rot. Chemical efforts to treat phytophthora root rot have been ineffective to control disease and have mostly been banned. So what is a gardener or farmer to do? (more…)

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Eaten alive from the inside: predatory bacteria kill pathogenic bacteria from the inside out

When it comes to predators, we naturally think of large, agile, and powerful animals on the prowl. But we often don’t think about the most abundant predators on our planet, predators of the microscopic world. In the depths of the microbial universe, predatory bacteria (those that feast upon other bacteria) have emerged. These bacteria are now ubiquitous in terrestrial and marine environments. Predatory bacteria penetrate the outer membrane of bacterial prey and ingest their prized nutrients, killing the prey. (more…)

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Microbes in costumes trick the immune system

Halloween has finally arrived and everyone around you has been busy working on their costumes in anticipation for this glorious day of tricks and treats. Come Halloween night, you may not even recognize the faces behind the costumes. How would you tell apart friends with a sweet tooth from foes ready for some tricks?

For some bacteria, putting on costumes is an everyday event when it comes to tricking the immune system. The immune system distinguishes the body's own cells from those of invading bacteria and viruses. Since the microbe's outer membrane is usually the first thing the immune system sees, the body takes advantage of molecules found on the outer membrane to generate an immune response. This seems like a wise defense mechanism but microbes have several tricks up their sleeves; they disguise themselves from the immune response by changing molecules on their outer membrane (antigenic variation) or by turning on and off expression of genes encoding for surface molecules (phase variation). (more…)