An enzyme is a substance that acts as a catalyst to induce a specific reaction and in a rapid manner. Most enzymes are derived from microorganisms and are largely responsible for the breakdown of organic matter. Enzymes are also important for those gardening organically, as organic fertilizer requires a high level of microbial activity in order for absorption. On top of helping with nutrient uptake, enzymes will also help prevent excess materials from building up around the root system and causing problems. Enzymes occur naturally in soil, and so for most outdoor gardens, there is no need for supplemental enzymes. However, in certain areas where the soil lacks enzymes, or in a soilless garden, these enzymes are absent. Adding enzymes to these hydroponic operations will boost the level of microbial activity in the root system, and allow for more efficient nutrient absorption.