AEM Accepts, published online ahead of print on 23 October 2009

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Appl. Environ. Microbiol. doi:10.1128/AEM.01774-09
Copyright (c) 2009, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Genome shuffling of Clostridium diolis DSM 15410 for improved 1,3-propanediol production

Burkhard Otte, Eike Grunwaldt, Osama Mahmoud, and Stefan Jennewein^*

Fraunhofer Institut für Molekularbiologie und Angewandte Ökologie, Forckenbeckstrasse 6, 52074 Aachen Germany

^* To whom correspondence should be addressed. Email: Stefan.jennewein{at}ime.fraunhofer.de.

Several microorganisms are known for their efficient anaerobic conversion of glycerol to 1,3-propanediol, with Clostridium diolis DSM 15410 as one of the better performers in terms of molar yield and volumetric productivity. However, this is still insufficient to compete with established chemical processes. Previous studies have shown that high concentrations of 1,3-propanediol, glycerol and fermentation side products can limit the productivity of C. diolis DSM 15410. Here we describe the use of genome shuffling of the strict anaerobe C. diolis DSM 15410 for improved 1,3-propanediol fermentation. Using chemical mutagenesis, strains with superior substrate and product tolerance were isolated and a higher product yield was obtained. These superior strains were then used for genome shuffling and selection for 1,3-propanediol and organic acid tolerance. After four rounds of genome shuffling and selection, significant improvements were observed, with one strain attaining a 1,3-propanediol volumetric yield of 85 g/l. This result represents an 80% improvement as compared to the parental wild-type strain.