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The polyhydroxyalkanoate biosynthesis genes are differentially regulated in planktonic- and biofilm-grown Pseudomonas aeruginosa

Paper ID Volume ID Publish Year Pages File Format Full-Text
24964 43549 2008 11 PDF Available
Title
The polyhydroxyalkanoate biosynthesis genes are differentially regulated in planktonic- and biofilm-grown Pseudomonas aeruginosa
Abstract

The planktonic and biofilm growth mode, the presence of polyhydroxyalkanoate (PHA) granules and the nitrogen availability were considered as parameters to study the regulation of genes involved in PHA biosynthesis in Pseudomonas aeruginosa. The transcriptional start point of the phaIF gene cluster, encoding PHA granule-associated proteins with proposed regulatory function, was experimentally verified. Gfp and lacZ transcriptional reporter fusions, respectively, were used to analyse promoter activities. In planktonic growth under nitrogen limitation, the phaC promoter (PphaC) showed increased induction, while in the PHA-negative mutant the activity of PphaC was reduced to 25% of the wild type and was independent of nitrogen availability. Promoter activity in biofilms was assessed using 2, 0.05 or 0 g/l of NH4Cl as nitrogen source, respectively. PphaC activity was increased during early biofilm growth, whereas in mature biofilms PphaC activity was preferentially localised to stalks of microcolonies. Nitrogen starvation led to an increased PphaC activity at the biofilm surface. PHA granule formation was confirmed by electron microscopy in planktonic and in biofilm cells. PphaI activity in planktonic cultures was less dependent on the conditions assayed and presented an oscillatory behaviour. In biofilms, PphaI was strongly activated during early stages of biofilm development, but was inactive in mature biofilms. Under nitrogen starvation PphaI activation resembled that of PphaC. These data suggested a differential regulation of PHA biosynthesis genes in planktonic and biofilm cells, as well as an important regulatory function of PhaF, when considering nitrogen availability. Interestingly, in biofilms PHA biosynthesis gene regulation showed a spatial distribution similar to rhamnolipid biosynthesis genes.

Keywords
Pseudomonas aeruginosa; PHA; Polyhydroxyalkanoate; Biofilms
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The polyhydroxyalkanoate biosynthesis genes are differentially regulated in planktonic- and biofilm-grown Pseudomonas aeruginosa
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 133, Issue 4, 29 February 2008, Pages 442–452
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us