Biodegradation
ENVIRONMENTAL ENGINEERING SCIENCE
Volume 21, Number 4, 2004
© Mary Ann Liebert, Inc.
Biosurfactant Enhancement of Microbial Degradation of Various Structural Classes of Hydrocarbon in Mixed Waste Systems
Suresh Inakollu,1 Huang-Chin Hung,2 and Gina S. Shreve2,*
1Enviro
Matrix Inc.
Detroit, MI 48202
2Department of Chemical Engineering and Materials Science
Wayne State University
Detroit, MI 48202
ABSTRACT
This study examines the effect of two rhamnolipid biosurfactants on the first-order biodegradation rate constant for a microbial consortium growing on a mixture of hydrocarbons representing four structural classes of hydrocarbons. The microbial biodegradation rate of hexadecane, dodecane, benzene, toluene, iso-octane, pristane (2,6,10,14 tetramethyl pentadecane), naphthalene, and phenanthrene in the presence and absence of a mixture of rhamnolipid biosurfactant was determined. A first-order biodegradation model was applied in these studies to better discern the differential solubilization and biodegradation rates for specific structural classes of hydrocarbons in hydrocarbon mixtures. The biodegradation rate was enhanced by the addition of biosurfactant levels above the critical micelle concentration for all hydrocarbon species except phenanthrene and naphthalene. The time required for complete removal of each of hydrocarbons from the culture was shortened due to the presence of surfactant, indicating a clear pattern in their order of removal based upon their structural class. The rhamnolipid biosurfactants enhanced the rate of linear alkane biodegradation more than the biodegradation rate of the monoaromatics. The rate constants for hexadecane and dodecane increased by 111 and 76% to 4.7 and 0.3 mg/h, respectively, while those of benzene and toluene increased by 34 and 65% to 3.1 and 4.0 mg/hr, respectively. The branched alkane degradation rate constants were also increased by 71% for iso-octane and 39% for pristane. In contrast,
Volume 21, Number 4, 2004
© Mary Ann Liebert, Inc.
Biosurfactant Enhancement of Microbial Degradation of Various Structural Classes of Hydrocarbon in Mixed Waste Systems
Suresh Inakollu,1 Huang-Chin Hung,2 and Gina S. Shreve2,*
1Enviro
Matrix Inc.
Detroit, MI 48202
2Department of Chemical Engineering and Materials Science
Wayne State University
Detroit, MI 48202
ABSTRACT
This study examines the effect of two rhamnolipid biosurfactants on the first-order biodegradation rate constant for a microbial consortium growing on a mixture of hydrocarbons representing four structural classes of hydrocarbons. The microbial biodegradation rate of hexadecane, dodecane, benzene, toluene, iso-octane, pristane (2,6,10,14 tetramethyl pentadecane), naphthalene, and phenanthrene in the presence and absence of a mixture of rhamnolipid biosurfactant was determined. A first-order biodegradation model was applied in these studies to better discern the differential solubilization and biodegradation rates for specific structural classes of hydrocarbons in hydrocarbon mixtures. The biodegradation rate was enhanced by the addition of biosurfactant levels above the critical micelle concentration for all hydrocarbon species except phenanthrene and naphthalene. The time required for complete removal of each of hydrocarbons from the culture was shortened due to the presence of surfactant, indicating a clear pattern in their order of removal based upon their structural class. The rhamnolipid biosurfactants enhanced the rate of linear alkane biodegradation more than the biodegradation rate of the monoaromatics. The rate constants for hexadecane and dodecane increased by 111 and 76% to 4.7 and 0.3 mg/h, respectively, while those of benzene and toluene increased by 34 and 65% to 3.1 and 4.0 mg/hr, respectively. The branched alkane degradation rate constants were also increased by 71% for iso-octane and 39% for pristane. In contrast,
References: ARONSTEIN, B.N., and ALEXANDER, M. (1993). Effects of a nonionic surfactant added to the soil surface on the desorption and biodegradation of sorbed aromatic compounds in soil. Environ. Sci. Technol. 25, 1728–1732. BURY, S.J., and MILLER, C.A. (1993). Effect of micellar solubilization on biodegradation rates of hydrocarbons. Environ. Sci. Technol. 27, 104–110. GOSWAMI, P., and SINGH, D. (1991). Different modes of hydrocarbon uptake by two Pseudomonas species. Biotechnol. two anionic glycolipid biosurfactants. J. Phys. Chem. 105 (50), 12596–12600. INAKOLLU, S., and SHREVE, G.S. (2002). Differential solubilization of hydrocarbon specie from complex NAPL mixtures by rhamnolipid biosurfactants. Environ. Sci. Technol. KING, J.P., and MARTEL, L.P. (1989). Using Oil Spill Dispersants on the Sea. Washington, DC: National Research Council; National Academy Press. systems. Environ. Sci. Technol. 25(11), 1920–1926. RITTMANN, B.E., and JOHNSON, N.M. (1989). Rapid biological cleanup of soils contaminated with lubricant oil. Water Sci. Technol. 21, 209–214. SEKELSKY, and SHREVE, G.S. (1999). Kinetic model of biosurfactant enhanced hexa-decane biodegradation by Pseudomonas aeruginosa. Biotechnol. Bioeng. 63(4), 401–409. THANGAMANI, S., and SHREVE, G.S. (1994). Effect of anionic biosurfactant on hexadecane purification in multiphase systems ENVIRON ENG SCI, VOL. 21, NO. 4, 2004