...From the pages of Agricultural Research magazine
Understanding how probiotics
influence development and
health of a young turkey's
gastrointestinal system is
a major component of ARS
collaborative research with
Mexican scientists. Visiting
scientist Memo Tellez (seated)
and Mexican graduate students
currently studying at the
University of Arkansas work
with physiologist Annie Donoghue
(behind Tellez) to evaluate how
these bacteria enhance the
enteric function. Standing
left to right are Alberto
Torres, Gerardo Nava, and
Probiotics are live, nonpathogenic bacteria that contribute
to the health and balance of the intestinal tract. They are given orally
to poultry to help the birds fight illness and disease. Prebiotics are
nondigestible foods or nutrients that probiotics need to stimulate metabolism.
They feed the beneficial bacteria and modify the composition of intestinal
microflora so probiotics can predominate.
Annie Donoghue is a poultry physiologist and research
leader at the ARS Poultry Production
and Product Safety Research Unit in Fayetteville, Arkansas. She's part
of a team of researchers finding new healthful bacteria to feed poultry
and beat back harmful pathogens while also making the poultry grow more
Donoghue is leading and coordinating the research team in several areas of probiotic research. Her husband, Dan Donoghue, is heading the Campylobacter work at the Department of Poultry Science at the University of Arkansas. Billy Hargis is leading the Salmonella work there. Guillermo Tellez, a visiting professor from the College of Veterinary Medicine at National Autonomous University of Mexico in Mexico City, was recently appointed as a researcher with the University of Arkansas and is exploring the interactions between the gut and bacteria. The team also includes several graduate students from both the United States and Mexico who have been integral team members on this project.
Candidate good bacteria
outcompete pathogens in
the laboratory. Here,
physiologist Annie Donoghue
gives a combination of these
bacteria to a turkey poult to
test their efficacy in the
Pathogens such as Salmonella and Campylobacter are the main causes of foodborne illness from poultry consumption. The research team wants to reduce microbial populations typically found in live poultry before they're processed for food. They're trying to get a better understanding of how probiotics influence the microbial environment of the gut and how they interact with other bacteria.
On the Market and in the Pipeline
One of the ways they are attempting to do this is identify good bacteria
(probiotics), test their ability to outcompete the bad bacteria in the
laboratory, and then use them to protect poultry.
The concept of the good bacteria outcompeting the bad is known as competitive exclusion and has been around for many years. Bacteria are fed to newly hatched poults and these bacteria occupy sites in the intestinal tract that would be optimal for pathogen attachment and colonization. Since the nonpathogenic bacteria get to the intestinal sites first and are able to colonize the gut, they reduce the opportunity for pathogenic bacteria to establish in newly hatched poults when they are most susceptible to infection.
Physiologist Annie Donoghue
and graduate student John
Holliman inspect plates to
identify bacteria that can
growth. Candidate bacteria are
placed in the center of a
plate containing Campylobacter.
Those that outcompete this
pathogen form a clear zone
(circle) of inhibition.
In fact, ARS scientists have been on the forefront of
this research. The Food and Feed Safety Research Unit in College Station,
Texas, developed PREEMPT, a blend of 29 organisms that can be sprayed
over newly hatched chicks to keep Salmonella from settling in
their intestines. It was licensed by FDA (U.S. Food and Drug Administration)
and manufactured commercially as a prophylactic. And ARS scientists
at the Poultry Microbiological Research Unit in Athens, Georgia, developed
the Mucosal Starter Culture to prevent the growth of Salmonella
and Campylobacter in newborn chicks. It is awaiting FDA approval.
The Fayetteville team consisting of ARS and University of Arkansas researchers have added a new dimension to this process by testing the ability of potential probiotic bacteria to outcompete the pathogens in vitro. Previous cultures have been less stringently screened. Commercial producers in developing countries had some success, but questions arose because some cultures were undefined (meaning not all the bacteria have been identified) and there is a fear in the United States and Europe that they could contain emerging pathogens.
Visiting scientist Memo
Tellez adds a probiotic
culture to the drinking water
of turkey poults. This field
trial is to test the
culture's ability to reduce
foodborne pathogens and
enhance growth and health
of the birds.
"The biggest challenge is determining the correct types and quantity of probiotics because of the numbers and diversity of microbes and the poorly understood interactions between the microbes and the intestine," Donoghue says.
So far the team has screened more than 4 million enteric isolates to come up with several promising probiotic combinations. The University of Arkansas and ARS have filed a patent on the selection techniques.
A Test To Identify Probiotics
"By using these preselected good microbes, we hope to produce
inexpensive, defined cultures with the ability to reduce or exclude
specific pathogens and enhance enteric health in poultry," Donoghue
says. "We've developed multiple in vitro selection systems for
identification of candidate organisms."
When they find potential probiotics, the researchers test and identify
the individual microbes in their labs and send them to the Arkansas
Livestock and Poultry Commission's diagnostic laboratory in Springdale
as a backup check. They also test these individual isolates to eliminate
potentially harmful microflora by injecting them into turkeys and chickens
and evaluating these birds for lesions and rates of disease and death.
Donoghue says the organisms they are selecting are very easy to propagate
in batch culture, using inexpensive growth media. These bacteria are
all facultative aerobes, meaning that they are oxygen tolerant. Producing
such organisms on a commercial scale is expected to be much less expensive
than some cultures that include strict anaerobes requiring complex equipment
This new method makes it much less expensive to produce probiotics.
This could both lower the price of poultry and make it less likely to
be a source of foodborne illnesses.By Jim
Core, Agricultural Research Service Information Staff.
This research is part of Food Safety (Animal and Plant Products),
an ARS National Program (#108) described on the World Wide Web at www.nps.ars.usda.gov.
Annie Donoghue is in the USDA-ARS Poultry Production and Product Safety Research Unit, Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701; phone (479) 575-2413, fax (479) 575-4202.
ARS's Reach Is Worldwide
Collaborations such as the Poultry Production and Product Safety Research
Unit's partnership with the University of Arkansas and Mexican scientists
to gain new insights into use of beneficial bacteria in poultry wouldn't
be possible without support from the ARS Office of International Research
Many ARS research projects are designed to tackle problems that have
impacts felt around the world. OIRP helps ARS researchers conduct research
in nations where mutual interests exist in areas including animal health,
biotechnology and biosafety, protection of crop health and pest control,
food safety, and water and environmental conservation.
With guidance from OIRP, ARS researchers throughout the United States
and overseas are collaborating with scientists from several nations,
including Brazil, Israel, and countries of the former Soviet Union.
Besides investigating food safety, Mexican counterparts are collaborating
on several projects.
For example, ARS researchers in Kerrville, Texas, are working with
scientists from Mexico's National Research Institute of Forestry and
Agriculture (INIFAP) in Cuernavaca, Morelos, to determine the nature
and scope of resistance in southern cattle ticks and horn flies to pyrethroid
and organophosphate pesticides. Their work includes developing practical
guidelines to manage this resistance and protect livestock. They hope
to create assays to monitor such resistance.
In another joint project, Mexican scientists in the Toluca Valley are
screening potato genotypes that ARS scientists are developing for resistance
to late blight (Phytopthora infestans), the most important potato
disease worldwide. Since all known strains of late blight have occurred
in the Toluca Valley, this cooperation is imperative if new varieties
are to resist potential future strains.
Eileen Herrera is an international affairs specialist with OIRP. She
indicates that many projects focus on issues that affect productivity,
trade between the United States and Mexico, and natural resources management
along our shared border. She says OIRP recently completed a pilot program
to exchange graduate students and postdoctoral researchers between Mexico
and the United States. She said the program not only increased cooperation
between the neighboring nations, but it also had the added benefit of
improving professional development within ARS, since the program emphasized
participation from the agency's early-career scientists.
Herrera says the latest direction in their relationship with Mexican
research institutions was to increase and enhance cooperation through
a series of five workshops, in partnership with INIFAP, ARS's counterpart
agency in Mexico. "The workshops are a mechanism for a more strategic
approach to cooperation between ARS and Mexican research institutions,"
Herrera says. "My hope is that within the next few years, we will
take what has already been a productive relationship between scientists
and their respective research locations and build on it to make it more
comprehensive at the agency level."By Jim
Core, Agricultural Research Service Information Staff.
Good for People Too?
Probiotics are good for people, too. All animals have naturally occurring beneficial probiotics in their guts. One commonly known probiotic, Lactobacillus acidophilus, is naturally present in foods such as yogurt, grains, and meat products. And prebiotics such as inulin have been used extensivelyparticularly in Europe and Japan where they're now included in many food products from sports drinks to baby formula.
"Probiotics Protect Poultry From Pathogens" was published in the January 2004 issue of Agricultural Research magazine.