News Update
September 7, 2010

Making Bacteria Unwelcome

A U.S. Department of Agriculture (USDA) scientist and his colleagues have discovered key gene and chemical interactions that allow Escherichia coli (E. coli) O157:H7 bacteria to colonize the gut of cattle. The animals not only host, but can shed the deadly human pathogen.

Many E. coli O157:H7 outbreaks have been associated with contaminated meat products and cross-contamination of produce crops. Because the bacteria do not cause cattle to show clinical symptoms of illness, and due to other unknown variables, they can be hard to detect within cattle and the environment.

The researchers, including USDA Agricultural Research Service (ARS) animal scientist Thomas Edrington, reported how the E. coli sense a key chemical that plays a critical role in allowing the bacteria to colonize inside the cattle’s gastrointestinal (GI) tract.

Edrington is with the ARS Food and Feed Safety Research Unit in College Station, Texas. The study, published in the Proceedings of the National Academy of Sciences, was conducted at the University of Idaho, Moscow, campus. It involved researchers from several universities and was headed by Vanessa Sperandio, who is with the University of Texas Southwestern Medical Center, in Dallas.

To proliferate, E. coli express genes differently based on their environment, such as outside the cattle host, inside the cattle rumen, or even at the end of the cattle GI tract. Having a better understanding of when, why and how these bacteria colonize could lead to practical applications in the future, according to Edrington.

The researchers showed that “quorum sensing” chemicals called acyl-homoserine lactones (AHLs), which are produced by other bacteria, are present within the bovine rumen but absent in other areas of the cattle GI tract. AHLs are important because E. coli harbor a regulator, called SdiA, which senses these AHLs and then prompts the E. coli to attach and colonize.

Limiting production of the SdiA chemical, or blocking bacterial reception of the AHLs, may eventually lead to new strategies for keeping E. coli from attaching inside the animal.

— Release by USDA-ARS.

Media Webinar: Europe, Middle East & Russia Beef Markets

The beef checkoff will offer a webinar featuring John Brook, U.S. Meat Export Federation (USMEF) regional director for Europe, Russia and the Middle East, who will provide an update on beef and beef products as it relates to Europe, the Middle East and Russian markets.

Russia’s re-emergence as a major market for U.S. beef exports continued to gain earlier this year, setting a new record for muscle-cut value at the end of June. Russia is the third-largest market (behind only Mexico and Egypt) for U.S. beef variety meat in terms of both volume and value.

Europe is still a very small market, but there has been some strong growth (about 60%) this year compared to 2009. The European Union’s recent opening of a new, zero-duty quota for high-quality beef has created expanded opportunities for producers and suppliers of U.S. beef.

The Middle East is the second-largest importer of U.S. beef variety meats, and beef muscle-cut exports are showing strong growth in this vibrant area.

John will also spend time highlighting why these markets are important to U.S. producers.

If you have any questions about this webinar, please e-mail Melissa Slagle at mslagle@beefboard.org or call 402-856-2097.

— Release by the Beef Checkoff Program.

Gulf Coast Tick Infests Arkansas Livestock

A tick that can cause ear deformities in cattle is firmly established in Arkansas, say researchers with the University of Arkansas (U of A).

The Gulf Coast tick “historically resided within 100 miles of the Gulf and Atlantic coasts,” said Kelly Loftin, Extension entomologist for the U of A Division of Agriculture. “It has since been redistributed with the transport of cattle and egret migration.”

The ticks arrived in Arkansas within the past decade, he said. Loftin was a co-author on a study completed in early 2010 that verified the Gulf Coast tick’s presence in Arkansas.

The tick can transfer heartwater disease, which can cause high fever and sudden death from encephalitis. However, the disease is almost exclusively found in sub-Saharan Africa and some Caribbean islands.

The tick’s biggest effect may be another part of the head.

“What we’re going to see in Arkansas is similar to what we’ve seen in other southern states that have the tick: cases of ‘gotch ear,’ in which a cow’s ear becomes infested with ticks and causes the ear to deform.”

The problem isn’t unsolvable, Loftin said. “It can be controlled. Ear tags impregnated with insecticide will stop the tick. Spray applications will work, too.”

Loftin said the state’s cattle might not currently be overrun with Gulf Coast ticks because insecticide-impregnated ear tags on cows work so well on this tick.

“I look at this news from the standpoint that this is just going to be an additional cattle pest for farmers to deal with.”

For more information about the Gulf Coast tick’s establishment in Arkansas, read the U of A study by Rebecca Trout at www.fcla.edu/FlaEnt/fe93p120.pdf.

— Release by U of A.

Microbial Breakthrough Impacts Health, Agriculture, Biofuels

For the first time ever, University of Illinois (U of I) researchers have discovered how microbes break down hemicellulose plant matter into simple sugars using a cow rumen bacterium as a model.

“This is ground-breaking research,” said Isaac Cann, associate professor in the U of I Department of Animal Sciences and member of the Energy Biosciences Institute (EBI) in the Institute for Genomic Biology. “The implications are very broad, yet it all started with a simple rumen microbe. It’s amazing how we can draw inferences to human health and nutrition, biofuel production, and animal nutrition because of our new understanding of how a microbe works.”

The cow rumen is an excellent model to study as it’s one of the most efficient machines to deconstruct plant matter, Cann said. Microbes in the rumen break down plant matter into glucose and xylose to use as nutrients for fermentation and energy acquisition.

U of I researchers utilized DNA sequencing and transcriptomics (RNAseq approach) to determine all of the enzymes the organism, Prevotella bryantii, uses to deconstruct hemicellulose into simple sugars.

“If you don’t completely understand what is happening, you can’t improve it,” Cann said.“The U of I’s strong history in anaerobic microbiology and genomics, and the EBI’s substantial funding enabled us to achieve this milestone. To my knowledge, this was the first time that anyone has systematically demonstrated the deconstruction of the plant cell wall hemicellulose.”

Breaking down hemicellulose is one of the biofuels industry’s greatest bottlenecks. Currently, the industry has microbes that can ferment simple sugars into liquid fuels such as ethanol and butanol. But they have struggled to break down feedstocks such as corn stover, switchgrass and miscanthus.

“U of I’s research has created an enzyme cocktail that can release simple sugars from hemicellulose and in turn, help the biofuels industry progress,” Cann said.

Even though researchers used a bacterium from the cow stomach, their results apply to microbes in the human large intestine, too. Human health and nutrition researchers are interested in the similar strategies certain rumen bacteria and human intestinal bacteria use to capture energy from dietary fiber.

“By fermenting the fiber in our diets, the microbes in our large intestine help to provide about 10% of our daily energy requirement,” he said. “The microbial fermentation products or short-chain fatty acids provide nutrition to the cells that line our intestines.”

Cann added that a greater understanding of the large population of microbes in the large intestine can impact a person’s health and nutritional status. For example, a simple change in the colon’s microbial population can contribute to the development of inflammatory bowel diseases.

“Understanding how different microbes obtain energy may allow us to modify our diets to select for beneficial microbes to promote better health,” he said.

The same principles hold true for livestock, he said.

“It’s not possible to understand the nutrition of farm animals without understanding the lifestyle of the microbial populations in their gut,” Cann said. “Cattle depend on microbes to obtain their energy from both grass and concentrate diets. A better understanding of how microbes capture nutrients from plant matter can help us to make animal agriculture more efficient.”

U of I researchers are building on the knowledge gained from this study to understand how two other major rumen bacteria capture energy from cellulose and cellulose/hemicellulose.

This study, “Transcriptomic analyses of xylan degradation by Prevotella bryantii and insights into energy acquisition by xylanolytic Bacteroidetes,” was published in the Journal of Biological Chemistry. Researchers include Dylan Dodd, Young Hwan Moon, Kankshita Swaminathan, Roderick Mackie and Isaac Cann of the Energy Biosciences Institute in the Institute for Genomic Biology at the University of Illinois.

— Release by U of I.

— Compiled by Mathew Elliott, assistant editor, Angus Productions Inc.