These organisms are heterotrophic and generally have complex nutritional requirements because they lack many biosynthetic capabilities.
Most species have multiple requirements for amino acids and vitamins.
Because of this, lactic acid bacteria are generally abundant only in communities where these requirements can be provided. Lactic acid bacteria are used in the food industry for several reasons. Their growth lowers both the carbohydrate content of the foods that they ferment, and the pH due to lactic acid production. It is this acidification process which is one of the most desirable side-effects of their growth. The pH may drop to as low as 4.0, low enough to inhibit the growth of most other microorganisms including the most common human pathogens, thus allowing these foods prolonged shelf life.