Structure and characterization of flavolipids, a novel class of biosurfactants produced by Flavobacterium sp. strain MTN11.
Herein we report the structure and selected properties of a new class of biosurfactants that we have named the flavolipids. The flavolipids exhibit a unique polar moiety that features citric acid and two cadaverine molecules. Flavolipids were produced by a soil isolate, Flavobacterium sp. strain MTN11 (accession number AY162137), during growth in mineral salts medium, with 2% glucose as the sole carbon and energy source. MTN11 produced a mixture of at least 37 flavolipids ranging from 584 to 686 in molecular weight (MW). The structure of the major component (23%; MW = 668) was determined to be 4-[[5-(7-methyl-(E)-2-octenoylhydroxyamino)pentyl]amino]-2-[2-[[5-(7-methyl-(E)-2-octenoylhydroxyamino)pentyl]amino]-2-oxoethyl]-2-hydroxy-4-oxobutanoic acid. The partially purified flavolipid mixture isolated from strain MTN11 exhibited a critical micelle concentration of 300 mg/liter and reduced surface tension to 26.0 mN/m, indicating strong surfactant activity. The flavolipid mixture was a strong and stable emulsifier even at concentrations as low as 19 mg/liter. It was also an effective solubilizing agent, and in a biodegradation study, it enhanced hexadecane mineralization by two isolates, MTN11 (100-fold) and Pseudomonas aeruginosa ATCC 9027 (2.5-fold), over an 8-day period. The flavolipid-cadmium stability constant was measured to be 3.61, which is comparable to that for organic ligands such as oxalic acid and acetic acid. In summary, the flavolipids represent a new class of biosurfactants that have potential for use in a variety of biotechnological and industrial applications.
Bodour
Adria A
AA
Department of Earth and Environmental Science, The University of Texas-San Antonio, San Antonio, Texas 78249, USA.
Guerrero-Barajas
Claudia
C
Jiorle
Beth V
BV
Malcomson
Mark E
ME
Paull
Amanda K
AK
Somogyi
Arpad
A
Trinh
Long N
LN
Bates
Robert B
RB
Maier
Raina M
RM
D000473:Alkanes; D001673:Biodegradation, Environmental; D045703:Emulsifying Agents; D005417:Flavobacterium / Q000254:growth & development / Q000378:metabolism*; D008074:Lipoproteins / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D012995:Solubility; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry* / Q000145:classification / Q000378:metabolism*
D000473:Alkanes; D045703:Emulsifying Agents; D008074:Lipoproteins; D008823:Micelles; D013501:Surface-Active Agents; C007932:n-hexadecane