News » Chapter 26 Microbial Ecology

The biofilm matrix

Contributed by mromalley on Aug 09, 2013 - 03:22 PM

In the microbial world, cooperation between multiple species is a novel way to combat the pressures of nutrient limitation, chemical damage, and other struggles that microorganisms constantly face. As such, dynamic and complex communities are frequently formed. An example of this is the biofilm—a thick, highly structured aggregate of microorganisms that often forms in aqueous environments, particularly along surfaces or at water-air interfaces. Biofilms owe their success to the fact that, under the correct conditions, many bacteria can secrete proteins, polysaccharides, and other materials into their immediate environment. When enough organisms accumulate in one location, this effect compounds to produce a dense network of extracellular polymeric substances, often termed EPS. The result is the formation of microscopic labyrinths, containing porous water channels, enzymes to degrade biopolymers into communal nutrients, even reseviors of naked DNA from lysed cells that other bacteria can uptake into their own genome. In this 2010 publication, researchers at the University of Duisburg-Essen performed an in-depth analysis of the structure of biofilm EPS and how they mediate the lives of the organisms within them.


Living at the mouth of an underwater volcano

Contributed by adtheis on Aug 09, 2013 - 12:22 PM

Deep-sea hydrothermal vents play host to an exciting array of marine life. At the base of these ecosystems are intricate communities of microorganisms. These bacteria and achaea survive at an astonishing range of temperatures, from more than 120°C at the mouth of the vents, to less than 10°C farther away. Characteristic to some genera is the assembly of orange and white “mats,” masses of bacteria turned colorful from the oxidation of sulfur. A recent article focuses on the dynamics of these communities, specifically in their relationships with temperature, at the Guaymas Basin hydrothermal vents in the Gulf of California

To eat or to be eaten? The complex lives of Dictyostelium discoideum and Pseudomonas fluorescens

Contributed by zretzlaff on Aug 02, 2013 - 09:44 AM

Dictyostelium discoideum is a eukaryotic microbe that lives a unique lifestyle that involves changing from a unicellular to multicellular organism. Recent studies have shown that not only is it unique in this aspect, but it is unique in that it actually cultivates its own food supply, being dubbed the world’s “smallest farmer” amongst microbiologists. This article is based on a recent study led by Debra Brock at the Washington Universty of St. Louis.

Dictyostelium discoideum is a heterotrophic, soil-living amoeba, and it’s unique in the fact that is starts out as a unicellular organism, but becomes a multicellular organism later in life. This occurs when its unicellular pieces come together to from a slug that can move around in the soil. But it’s not just unique in this aspect. It is also a rare species because it has been proven to carry its bacterial prey around with it and essentially “farm” it for a larger food supply

A Community of Microbes Help Protect Plants from Disease.

Contributed by jkmladucky on Aug 01, 2013 - 12:09 PM

The immune system of animals is extremely complex and helps defend against a plethora of diseases. Plants, on the other hand, are not as lucky when it comes to defense. Plants have a few systems to stop chemicals and diseases from moving in, but overall are very susceptible to infection. Scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory have found that many plants are relying on microbes in the soil to defend themselves against diseases and pathogens.

Human Microbiome Project

Contributed by sciencesmith on Jul 25, 2013 - 01:55 PM

Typically we think of biomes as large communities of organisms covering vast areas; but a new idea of microbiome is becoming popularized as our understanding of microorganisms grows. The human body is just such a microbiome. For every one human cell in the body there are 10 microbial cells! If that sounds like disportionate amount and you find yourself wondering how it is possible to have more microbial cells than human cells, consider the fact that a typical microbe cell is much smaller than a human cell and can fit in between the spaces of human cells. In a 200 pound adult, it roughly amounts to 2-6 pounds.

These microbes are mostly bacterial, many of which are critical to the body’s healthy growth and function. Bacteria live inside our digestive system and help our bodies digest nutrients and synthesize vitamins. Many also help our immune systems fight disease or even other harmful bacteria. In return these bacteria receive their own small share of nutrients. Like it or not, our bodies are ecosystems complete with niches that other organisms compete for.

The microbial communities surrounding radioactive waste dumps

Contributed by adtheis on Jul 23, 2013 - 02:47 PM

Growing interest in nuclear power is often hindered by the question of what to do with the radioactive byproducts. One solution is to bury them. In Mol, Belgium, at the HADES research center, scientists have discovered communities of microbes living in the clay surrounding structures that house nuclear waste. Some species of microorganisms are known to have detrimental effects on the materials used for these structures. Researchers have delved hundreds of meters underground in search of what kinds of microbial communities are present, and what relationship they might have with the poisonous compounds we've introduced to them

The Microbial Effects of Climate Change

Contributed by paustian on Jun 28, 2013 - 03:07 PM

It isn't often when scientists and policy makers think about the effects of climate change that they consider the microbial population. Microbes are 60% of the biomass on earth and have profound effects on the global environment. As a demonstration of this, Professor Ferran Garcia-Pichel of Arizona State University has studied the microbes present in desert soil using new molecular survey techniques. These methods allow researchers to rapidly characterize the population of microbes present.

Another benefit to wetlands - Carbon sinks

Contributed by paustian on Jun 25, 2013 - 03:15 PM

Balnca Bernal and William Mitsch have just published a paper in the Journal of Environmental Quality that looks at the potential of wet lands to serve as carbon sinks. Their paper shows that wetlands accumulate 242 g of carbon m-2 yr-1. This is 70% more than a natural wetland. Wetlands are great at trapping carbon because when plants that  grow in the shallow water die, they fall into the water and must be degraded anaerobically. This is a much slower process, and a significant fraction of the carbon may not be degraded for thousands of years. Wet lands are also a great way for farmers to prevent farm runoff, purify the water and provide habitat for wildlife.  You can also read a press release about the research.

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