Tobin et al_AEM v73_2007_p1383

Tobin et al_AEM v73_2007_p1383 - APPLIED AND ENVIRONMENTAL...

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A PPLIED AND ENVIRONMENTAL MICROBIOLOGY, Feb. 2007, p. 1383–1387 Vol. 73, No. 4 0099-2240/07/$08.00 1 0 doi:10.1128/AEM.02007-06 Copyright © 2007, American Society for Microbiology. All Rights Reserved. Polyphosphate Accumulation by Pseudomonas putida CA-3 and Other Medium-Chain-Length Polyhydroxyalkanoate-Accumulating Bacteria under Aerobic Growth Conditions £ Karen M. Tobin, 1 John W. McGrath, 2 Alan Mullan, 2 John P. Quinn, 2 and Kevin E. O’Connor 1 * School of Biomolecular and Biomedical Sciences, College of Life Sciences, and Centre for Synthesis and Chemical Biology, the Conway Institute for Biomolecular and Biomedical Science, University College Dublin, BelFeld, Dublin 4, Ireland, 1 and School of Biology and Biochemistry and QUESTOR Centre, the Queen’s University of Belfast, Medical Biology Centre, 97 Lisburn Rd., Belfast BT9 7BL, Ireland 2 Received 23 August 2006/Accepted 1 December 2006 Pseudomonas putida CA-3 accumulates polyphosphate (polyP) and medium-chain-length polyhydroxyalkanoate (mclPHA) concurrently under nitrogen limitation. Five other mclPHA-accumulating Pseudomonas strains are capable of simultaneous polyP and mclPHA biosynthesis. It appears that polyP is not the rate-limiting step for mclPHA accumulation in these Pseudomonas strains. Certain microorganisms can accumulate energy reserve com- pounds, including glycogen (8, 23), lipids (1, 8), polyphosphate (polyP) (8, 11), and polyhydroxyalkanoate (PHA) (8, 13). Pre- vious studies have reported the dual accumulation of such materials by various microorganisms (8, 28). However, the dual accumulation of medium-chain-length PHA (mclPHA) and polyP has not been reported. PolyP is a linear polymer ranging in length from 3 to more than 1,000 phosphate residues linked by high-energy phosphoanhydride bonds (11, 14, 16). Multiple roles have been suggested for polyP in the physiological adap- tation of microorganisms during growth and development and in response to nutritional and environmental stress (3, 14, 16, 21). PHAs are a group of biodegradable polymers accumulated by bacteria as an intracellular carbon storage material gener- ally in response to inorganic nutrient limitation in the presence of excess carbon (13, 25, 27). Polyhydroxybutyrate (PHB), the best-known PHA, contains four carbon monomers and is re- ferred to as short-chain-length PHA. PHA containing mono- mers with six or more carbons is termed medium-chain-length PHA. A link between polyP and PHB accumulation has been widely reported in studies of phosphate removal from waste- water by enhanced biological phosphorus removal, where mi- crobial sludges are exposed to alternating anaerobic/aerobic cycles (6, 28, 15). PHB accumulated in the anaerobic cycle is subsequently degraded in the aerobic cycle to provide energy for phosphate uptake and polyP biosynthesis. The proceeding anaerobic cycle results in the breakdown of the intracellular polyP, which provides energy for the uptake of organic sub- strates and results in the accumulation of PHB (12).
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This note was uploaded on 08/06/2008 for the course ESM 219 taught by Professor Holden during the Fall '07 term at UCSB.

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Tobin et al_AEM v73_2007_p1383 - APPLIED AND ENVIRONMENTAL...

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