This press relase is available in Spanish. Spoilage1(损坏,糟蹋) bacteria that can cause red coloration of pickles3' skin during fermentation(发酵) may actually help clean up dyes(染料) in textile industry wastewater, according to a U.S. Department of Agriculture (USDA) study.
Some species of Lactobacilli-food-related microorganisms-can cause red coloring when combined with tartrazine(酒石黄) , a yellow food-coloring agent used in the manufacture of dill pickles(腌黄瓜) . Now Agricultural Research Service (ARS) microbiologist Ilenys Pérez-Díaz and her colleagues have found that these spoilage Lactobacilli also may have environmental benefits. ARS is USDA's principal intramural scientific research agency.
The scientists from the ARS Food Science Research Unit in Raleigh, N.C., noted4 that several Lactobacilli modify azo dyes(偶氮染料) , which are used in the textile industry and may wind up in wastewater if untreated. These azo dyes impart vivid and warm colors such as red, orange and yellow to fabric5. Though many azo dyes are nontoxic, some have been found to be mutagenic(诱变的) .
This is the first report that food-related microorganisms can transform azo dyes into non-mutagenic substances. The findings from this work have been reported in the Journal of Applied6 Microbiology.
According to Pérez-Díaz, considerable effort has been made to identify microorganisms capable of degrading azo dyes in wastewater. If food-grade Lactobacilli capable of degrading a range of azo dyes were identified, they might become organisms of choice for wastewater treatment applications.
This discovery was made during Pérez-Díaz's search for the culprit(犯人,罪犯) responsible for causing some commercial dill pickles to have red spoilage bacteria. Pérez-Díaz and her colleagues isolated7 Lactobacilli from spoiled jars of hamburger dill pickles and used those isolates8 to inoculate9 non-spoiled jars of hamburger dill pickles. Jars that contained brines(卤水,盐水) with tartrazine developed the red hue10 on the pickle2 skins; those that had turmeric(姜黄) or no added coloring did not.
Seven treatments were tested to find a preventive measure for red-colored spoilage. Pérez-Díaz found that adding sodium11 benzoate prevented bacterial12 growth and the development of red-colored spoilage in hamburger pickles.