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Applied and Environmental Microbiology, July 2009, p. 4676-4686, Vol. 75, No. 14
0099-2240/09/$08.00+0     doi:10.1128/AEM.02486-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Community Structure Evolution and Enrichment of Glycogen-Accumulating Organisms Producing Polyhydroxyalkanoates from Fermented Molasses{triangledown}

Ana R. Pisco,1 Simon Bengtsson,2 Alan Werker,2 Maria A. M. Reis,1 and Paulo C. Lemos1*

REQUIMTE/CQFB, Chemistry Department, FCT/Universidade Nova de Lisboa, 2829-516 Caparica, Portugal,1 AnoxKaldnes AB, Klosterängsvägen 11A, SE-226 47 Lund, Sweden2

Received 30 October 2008/ Accepted 13 May 2009

An open mixed culture was enriched with glycogen-accumulating organisms (GAOs) by using a sequencing batch reactor and treating an agroindustrial waste (sugar cane molasses) under cyclic anaerobic-aerobic conditions. Over a 1-year operating period, the culture exhibited a very stable GAO phenotype with an average polyhydroxyalkanoate (PHA) content of 17% total suspended solids. However, the GAO microbial community evolved over the course of operation to a culture exhibiting unusual characteristics in producing PHAs comprised of short-chain-length monomers, namely, 3-hydroxybutyrate, 3-hydroxy-2-methylbutyrate, 3-hydroxyvalerate, and 3-hydroxy-2-methylvalerate, and also, up to 31 mol% of the medium-chain-length (MCL) monomer 3-hydroxyhexanoate (3HHx). Microbial community analysis by fluorescence in situ hybridization revealed a concurrent long-term drift in the GAO community balance, from mainly "Candidatus Competibacter phosphatis" to mainly Defluviicoccus vanus-related organisms. The production of 3HHx was confirmed by 13C nuclear magnetic resonance (NMR) and appeared to be related to the increased presence of D. vanus-related GAOs. These results suggest a broadened spectrum of material, chemical, and mechanical properties that can be achieved for biopolymers produced by open mixed cultures from fermented waste. The increased spectrum of polymer properties brings a wider scope of potential applications.

* Corresponding author. Mailing address: REQUIMTE/CQFB, Chemistry Department, FCT/UNL, 2829-516 Caparica, Portugal. Phone: 351 212949617. Fax: 351 212948385. E-mail: pac{at}dq.fct.unl.pt

{triangledown} Published ahead of print on 22 May 2009.

Applied and Environmental Microbiology, July 2009, p. 4676-4686, Vol. 75, No. 14
0099-2240/09/$08.00+0     doi:10.1128/AEM.02486-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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