Generate bioactive ingredients from lactic acid bacteria.

In a five-year project slated to last through 2009, USDA-ARS scientists are in the process of developing lactic fermentation bacteria with the genetic capacity to produce natural or milk-based bioactive food ingredients. Bioactive ingredients are food components, other than those needed to meet basic human nutritional needs, that are responsible for mostly positive changes in human health.

The goal of researchers is to improve the health-promoting, functional and bioprotective properties of foods by utilizing microbial, molecular, gene, enzyme and proteomic technologies. They also are evaluating production media formulated from dairy wastes, such as whey.

Microbial and molecular biotechnology, gene, enzyme and proteomic technologies will be harnessed by the researchers to develop selected lactic fermentation and probiotic bacteria used in dairy food production with the capacity to generate bioactive peptides. Transport systems fitted with regulatory elements will be constructed to deliver genes into food-grade bacteria--streptococci, lactococci, lactobacilli.

In addition, the investigators are optimizing gene transfer and stability conditions, nutrient requirements and other growth parameters for gene product synthesis. These will be secreted in selected host systems. Superior cultures will be tested for productivity in fermentation media based on whey effluents from dairy production. Cell lines and their products will be evaluated in prototype food systems.

The lactic acid bacteria are a group of Gram-positive bacteria, non-respiring, non-spore-forming cocci or rods, which produce lactic acid as the major end product of the fermentation of carbohydrates. Lactic acid bacteria carry out their reactions--the conversion of carbohydrate to lactic acid, carbon dioxide and other organic acids--without the need for oxygen. They are microaerophilic.

Because of this, the changes that they affect do not cause drastic changes in the composition of food. Despite their complexity, the whole basis of lactic acid fermentation centers on the ability of lactic acid bacteria to produce acid, which then inhibits the growth of other, non-desirable organisms.

Further information. George Somkuti, USDA-ARS Eastern Regional Research Center, Room 1119, Dairy Processing and Products Research, 600 E. Mermaid Lane, Wyndmoor, PA 19038; phone: 215-233-6474; fax: 215-233-6795; email: george.somkuti@ars.usda.gov.