Production of fermentation products containing rhamnolipids

A process for producing rhamnolipids by bacterial fermentation comprising:

• A) preparing a bacterial seed culture comprising at least one rhamnolipid producing bacteria;
• B) preparing a fermentation medium in a suitable fermentation vessel, said fermentation medium comprising a carbon source, a nitrogen source, and a non-nitrogen source comprising phosphorus, sulfur, potassium, sodium, calcium, magnesium, chloride, iron, manganese, zinc, boron, cobalt, copper, and molybdenum;
• C) adding the bacterial seed culture comprising rhamnolipid producing bacteria and at least one of air and oxygen to the fermentation medium to form a fermentation broth;
• D) growing the rhamnolipid producing bacteria in said fermentation broth;
• E) periodically adding additional quantities of said nitrogen source to allow said rhamnolipid producing bacteria to grow until said non-nitrogen source is substantially consumed, wherein rhamnolipid producing bacteria growth substantially stops and rhamnolipids are produced;
• F) periodically supplementing said nitrogen source maintain a substantially non-decreasing rate of rhamnolipids production until the rhamnolipid concentration in the fermentation broth reaches a concentration of from about 50 g/L to about 200 g/L;
• G) removing some or all of the fermentation broth and harvesting the rhamnolipids contained therein.

A method for reducing or eliminating excessive foaming during the growth phase of fermentation-based rhamnolipid production comprising:

• A) determining a quantity of each one of said at least one carbon source, at least one nitrogen source, and non-nitrogen source necessary to grow said rhamnolipid producing bacteria to a desired cell concentration;
• B) forming an initial fermentation medium comprising some or all of said quantity of the at least one carbon source necessary to grow said rhamnolipid producing bacteria to the desired cell concentration, some or all of said quantity of said non-nitrogen source necessary to grow said rhamnolipid producing bacteria to the desired cell concentration, and a first portion said quantity of the at least one nitrogen source necessary to grow said rhamnolipid producing bacteria to the desired cell concentration, wherein said initial fermentation medium comprises phosphorus, sulfur, potassium, sodium, calcium, magnesium, chloride, iron, manganese, zinc, boron, cobalt, copper, and molybdenum;
• C) adding said rhamnolipid producing bacteria to said initial fermentation medium to form said fermentation broth and growing said rhamnolipid producing bacteria until the first portion of said at least one nitrogen source has been substantially consumed;
• and
• D) adding any remaining carbon source and non-nitrogen source to said fermentation broth and gradually adding a remaining portion of said quantity of said at least one nitrogen source to said fermentation broth, to continue growing said rhamnolipid producing bacteria at a rate that is slow enough to reduce or substantially eliminate excessive foaming until the remaining portion of said quantity of nitrogen source has been substantially consumed or growth of said rhamnolipid producing bacteria stops.