FOOD-GRADE VECTOR SUITABLE FOR TRANSFORMING A FOOD-GRADE HOST CELL, USE OF SAID VECTOR FOR TRANSFORMING FOOD-GRADE HOST CELLS AND USE OF SAID TRANSFORMED CELLS IN BIOTRANSFORMATION PROCESSES

摘要

A food-grade vector is provided which is suitable for transforming afood-grade host cell and is incapable of replicating autonomously in said host cell, said vector comprising: 1) at least one stretch of nucleotides capable of hybridizing with chromosomal DNA of the non-transformed host cell enabling said vector to integrate stably into the chromosome of said host cell after transformation and 2) at least one stretch of foreign DNA selected from: a) stretches comprising at least one DNA sequence that codes for at least one product enabling the transformed host cell to metabolize a substrate that cannot be metabolized by the nontransformed host cell, wherein at least said DNA sequence and the product encoded by said DNA sequence are foreign for a prototrophic strain of said non-transformed host cell b) stretches comprising at least one DNA sequence that codes for at least one product enabling the transformed host cell to grow in the presence of a food grade, natural bacteriocidal agent, wherein at least said DNA sequence and the product encoded by said sequence are foreign for the non-transformed host cell. The food-grade host is preferably a lactic acid bacterium. The foreign DNA preferably codes for an enzyme essential for metabolizing an oligosaccharide or codes for a proteinase and a maturase or codes for a foodgrade natural bacteriocidal agent and/or immune proteins for such an agent and/or proteins involved in the proper secretion of such an agent.