Document Detail


Metabolic relationship between polyhydroxyalkanoic acid and rhamnolipid synthesis in Pseudomonas aeruginosa: comparative ¹³C NMR analysis of the products in wild-type and mutants.
MedLine Citation:
PMID:  21029757     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
Polyhydroxyalkanoic acids (PHAs) and rhamnolipids considered as biotechnologically important compounds are simultaneously produced by Pseudomonas aeruginosa. Both are synthesized from common precursors, (R)-3-hydroxyfatty acids. To find the probable metabolic relationship between their syntheses, we investigated the PHA and rhamnolipids production in four pha (phaC1, phaC2, phaZ, and phaG), four rhl (rhlA, rhlB, rhlR, and rhlI) and rpoS mutant strains of P. aeruginosa PA14 and PAO1 grown in minimal medium containing 70 mM fructose or 30 mM decanoic acid. Higher PHA accumulation was found in the rhamnolipid-negative mutants than in the wild-type strains, suggesting that 3-hydroxyfatty acid precursors become more available for PHA synthesis when rhamnolipids synthesis is absent. However, compared to the wild-type strains, rhamnolipids production was not enhanced in the four pha mutants of P. aeruginosa PA14 and PAO1 which indicates that rhamnolipids production in P. aeruginosa could be tightly regulated at the transcriptional level by a quorum-sensing response. The metabolic pathways for PHA and rhamnolipid synthesis from medium-chain-length fatty acids were also investigated using octanoic-1-¹³C acid. ¹³C NMR analysis revealed that the monomer-unit (R)-3-hydroxyoctanoate-1-¹³C being converted from the octanoic acid substrate was effectively incorporated into PHA. In the rhamnolipid synthesis, the (R)-3-hydroxyoctanoate-1-¹³C is suggested to be firstly converted to (R)-3-hydroxydecanoate-1,3-¹³C via fatty acid de novo biosynthesis pathway and then further processed into (R)-3-((R)-3-hydroxyalkanoyloxy)alkanoic acids (HAAs) via RhlA. The ratio of mono- to dirhamnolipids in the product depended on the type of carbon sources. The rhlB mutant could be exploited as an efficient producer of the important biosurfactant HAAs (e.g., ~700 mg/L HAAs was obtained when grown on 60 mM octanoic acid).
Authors:
Mun Hwan Choi; Ju Xu; Merced Gutierrez; Taesik Yoo; You-Hee Cho; Sung Chul Yoon
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-10-26
Journal Detail:
Title:  Journal of biotechnology     Volume:  151     ISSN:  1873-4863     ISO Abbreviation:  J. Biotechnol.     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-01-03     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8411927     Medline TA:  J Biotechnol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  30-42     Citation Subset:  IM    
Copyright Information:
© 2010 Elsevier B.V. All rights reserved.
Affiliation:
Nano-Biomaterials Science Laboratory, Division of Applied Life Sciences (BK21), Graduate School, Gyeongsang National University, Jinju 660-701, Republic of Korea.
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