Link between microbial composition and carbon substrate-uptake preferences in a PHA-storing community.
The microbial community of a fermented molasses-fed sequencing batch reactor (SBR) operated under feast and famine conditions for production of polyhydroxyalkanoates (PHAs) was identified and quantified through a 16 S rRNA gene clone library and fluorescence in situ hybridization (FISH). The microbial enrichment was found to be composed of PHA-storing populations (84% of the microbial community), comprising members of the genera Azoarcus, Thauera and Paracoccus. The dominant PHA-storing populations ensured the high functional stability of the system (characterized by high PHA-storage efficiency, up to 60% PHA content). The fermented molasses contained primarily acetate, propionate, butyrate and valerate. The substrate preferences were determined by microautoradiography-FISH and differences in the substrate-uptake capabilities for the various probe-defined populations were found. The results showed that in the presence of multiple substrates, microbial populations specialized in different substrates were selected, thereby co-existing in the SBR by adapting to different niches. Azoarcus and Thauera, primarily consumed acetate and butyrate, respectively. Paracoccus consumed a broader range of substrates and had a higher cell-specific substrate uptake. The relative species composition and their substrate specialization were reflected in the substrate removal rates of different volatile fatty acids in the SBR reactor.
REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Lisboa, Portugal.
Maria G E
MG
Albuquerque
Gilda
G
Carvalho
Caroline
C
Kragelund
Ana F
AF
Silva
Maria T
MT
Barreto Crespo
Maria A M
MA
Reis
Per H
PH
Nielsen
D000085:Acetates / Q000378:metabolism; D019149:Bioreactors; D002087:Butyrates / Q000378:metabolism; D005285:Fermentation; D017404:In Situ Hybridization, Fluorescence; D008965:Molasses; D054813:Polyhydroxyalkanoates / Q000378:metabolism*; D011422:Propionates / Q000378:metabolism; D020560:Proteobacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D000085:Acetates; D002087:Butyrates; D054813:Polyhydroxyalkanoates; D011422:Propionates