Transport and intracellular metabolism of major feed compounds by ruminal bacteria: the potential for metabolic manipulation

Current knowledge of the uptake and metabolism of the major energy yielding and nitrogenous nutrients that are naturally available to ruminal bacteria is reviewed. The potential use of metabolic engineering to manipulate these metabolic pathways and improve nutrient utilization in ruminant animals is briefly discussed. Metabolic engineering is the use of recombinant DNA techniques to enhance microbial function by manipulating enzymatic, transport and regulatory functions of the cell. Examples of the use of metabolic engineering in industrial fermentation are also given.