Linked Life Data

11796172

Source:http://linkedlifedata.com/resource/pubmed/id/11796172

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2002-1-17
pubmed:abstractText
The rhamnolipid biosurfactant produced by Pseudomonas aeruginosa influences various processes related to hydrocarbon degradation. However, degradation can only be enhanced by the surfactant when it stimulates a process that is rate limiting under the applied conditions. Therefore we determined how rhamnolipid influences hexadecane degradation by P. aeruginosa UG2 under conditions differing in hexadecane availability. The rate of hexadecane degradation in shake flask cultures was lower for hexadecane entrapped in a matrix with 6 nm pores (silica 60) or in quartz sand than for hexadecane immobilized in matrices with pore sizes larger than 300 nm or for hexadecane present as a separate liquid phase. This indicates that the availability of hexadecane decreased with decreasing pore size under these conditions. The rate-limiting step for hexadecane entrapped in silica 60 was the mass transfer of substrate from the matrix to the bulk liquid phase, whereas for hexadecane present as a second liquid phase it was the uptake of the substrate by the cells. Hexadecane degradation in batch incubations was accelerated by the addition of rhamnolipid or other surfactants in all experiments except in those where hexadecane was entrapped in silica 60, indicating that the surfactants stimulated uptake of hexadecane by the cells. Since rhamnolipid stimulated the degradation rate in batch experiments to a greater extent than any of the other 14 surfactants tested, hexadecane uptake was apparently more enhanced by rhamnolipid than by the other surfactants. Although rhamnolipid did not stimulate the release of hexadecane from silica 60 under conditions of intense agitation, it significantly enhanced this rate during column experiments in the absence of strain UG2. The results demonstrate that rhamnolipid enhances degradation by stimulating release of entrapped substrate in column studies under conditions of low agitation and by stimulating uptake of substrate by the cells, especially when degradation is not limited by release of substrate from the matrices.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0168-1656
pubmed:author
pubmed:issnType
Print
pubmed:day
28
pubmed:volume
94
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
195-212
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
The enhancement by surfactants of hexadecane degradation by Pseudomonas aeruginosa varies with substrate availability.
pubmed:affiliation
Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't