Featured Research

from universities, journals, and other organizations

Protecting Romaine Lettuce From Pathogens

Date:
July 3, 2008
Source:
USDA/ Agricultural Research Service
Summary:
Knowing the preferences of foodborne pathogens such as Escherichia coli O157:H7 is essential to a successful counterattack on these microbes. That's why microbiologists are scrutinizing the little-understood ability of E. coli O157:H7 and Salmonella enterica to contaminate romaine lettuce.

ARS research assistant Danielle Goudeau inoculates a romaine lettuce leaf with E. coli O157:H7 to study the pathogen's biology on salad greens.
Credit: USDA

Knowing the preferences of foodborne pathogens such as Escherichia coli O157:H7 is essential to a successful counterattack on these microbes. That's why Agricultural Research Service (ARS) microbiologist Maria T. Brandl and University of California-Berkeley colleague Ronald G. Amundson are scrutinizing the little-understood ability of E. coli O157:H7 and Salmonella enterica to contaminate romaine lettuce.

Brandl is with the ARS Produce Safety and Microbiology Research Unit, part of the agency's Western Regional Research Center in Albany, Calif.

In experiments, the scientists exposed romaine lettuce leaves to E. coli O157:H7 and found that, after 24 hours, populations of the microbe were 10 times higher on young leaves than on middle ones.

One explanation: The young leaves are a richer nutritional "hunting ground" for E. coli. They exude about three times more nitrogen and about 1.5 times more carbon than do the middle leaves, Brandl and Amundson reported.

Scientists have known for decades that plants exude compounds--from leaves and roots--that bacteria and fungi can use as food. But the romaine lettuce study, published earlier this year in Applied and Environmental Microbiology, is the first to document the different exudate levels in romaine lettuce leaves of the two age classes. It's also the first to show that E. coli can do more than simply bind to the leaves; it also can multiply.

Adding nitrogen to the middle leaves boosted E. coli growth and further pointed to a key role of nitrogen in helping this pathogen. For that reason, a strategy that decreases nitrogen fertilizer use in romaine lettuce fields may be worth investigating, Brandl noted.

According to James A. Lindsay, ARS national program leader for food safety research, commodity-specific food safety guidelines for producing and harvesting leafy greens such as lettuce have been developed. That was done through industry, government and academic collaboration, in an effort to support Good Agricultural Practices, or GAPs.


Story Source:

The above story is based on materials provided by USDA/ Agricultural Research Service. Note: Materials may be edited for content and length.


Cite This Page:

USDA/ Agricultural Research Service. "Protecting Romaine Lettuce From Pathogens." ScienceDaily. ScienceDaily, 3 July 2008. <www.sciencedaily.com/releases/2008/06/080629081503.htm>.
USDA/ Agricultural Research Service. (2008, July 3). Protecting Romaine Lettuce From Pathogens. ScienceDaily. Retrieved August 30, 2014 from www.sciencedaily.com/releases/2008/06/080629081503.htm
USDA/ Agricultural Research Service. "Protecting Romaine Lettuce From Pathogens." ScienceDaily. www.sciencedaily.com/releases/2008/06/080629081503.htm (accessed August 30, 2014).

Share This




More Health & Medicine News

Saturday, August 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Liberia Continues Fight Against Ebola

Liberia Continues Fight Against Ebola

AFP (Aug. 30, 2014) Authorities in Liberia try to stem the spread of the Ebola epidemic by raising awareness and setting up sanitation units for people to wash their hands. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
California Passes 'yes-Means-Yes' Campus Sexual Assault Bill

California Passes 'yes-Means-Yes' Campus Sexual Assault Bill

Reuters - US Online Video (Aug. 30, 2014) California lawmakers pass a bill requiring universities to adopt "affirmative consent" language in their definitions of consensual sex, part of a nationwide drive to curb sexual assault on campuses. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
3 Things To Know About The Ebola Outbreak's Progression

3 Things To Know About The Ebola Outbreak's Progression

Newsy (Aug. 29, 2014) Here are three things you need to know about the deadly Ebola outbreak's progression this week. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins