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Enhanced benzaldehyde tolerance in zymomonas mobilis biofilms and the potential of biofilm applications in fine-chemical production

Enhanced benzaldehyde tolerance in zymomonas mobilis biofilms and the potential of biofilm applications in fine-chemical production
Enhanced benzaldehyde tolerance in zymomonas mobilis biofilms and the potential of biofilm applications in fine-chemical production
Biotransformation plays an increasingly important role in the industrial production of fine chemicals due to its high product specificity and low energy requirement. One challenge in biotransformation is the toxicity of substrates and/or products to biocatalytic microorganisms and enzymes. Biofilms are known for their enhanced tolerance of hostile environments compared to planktonic free-living cells. Zymomonas mobilis was used in this study as a model organism to examine the potential of surface-associated biofilms for biotransformation of chemicals into value-added products. Z. mobilis formed a biofilm with a complex three-dimensional architecture comprised of microcolonies with an average thickness of 20 ?m, interspersed with water channels. Microscopic analysis and metabolic activity studies revealed that Z. mobilis biofilm cells were more tolerant to the toxic substrate benzaldehyde than planktonic cells were. When exposed to 50 mM benzaldehyde for 1 h, biofilm cells exhibited an average of 45% residual metabolic activity, while planktonic cells were completely inactivated. Three hours of exposure to 30 mM benzaldehyde resulted in sixfold-higher residual metabolic activity in biofilm cells than in planktonic cells. Cells inactivated by benzaldehyde were evenly distributed throughout the biofilm, indicating that the resistance mechanism was different from mass transfer limitation. We also found that enhanced tolerance to benzaldehyde was not due to the conversion of benzaldehyde into less toxic compounds. In the presence of glucose, Z. mobilis biofilms in continuous cultures transformed 10 mM benzaldehyde into benzyl alcohol at a steady rate of 8.11 g (g dry weight)?1 day?1 with a 90% molar yield over a 45-h production period
0099-2240
1639-1644
Li, Xuan Zhong
352996bd-e0f7-46b2-a162-045fe80e26ea
Webb, Jeremy S.
ec0a5c4e-86cc-4ae9-b390-7298f5d65f8d
Kjelleberg, Staffan
043b66b5-130c-42f2-99b3-ec3eecf3248e
Rosche, Bettina
e9461756-47b3-4697-8fc6-2a37fc524431
Li, Xuan Zhong
352996bd-e0f7-46b2-a162-045fe80e26ea
Webb, Jeremy S.
ec0a5c4e-86cc-4ae9-b390-7298f5d65f8d
Kjelleberg, Staffan
043b66b5-130c-42f2-99b3-ec3eecf3248e
Rosche, Bettina
e9461756-47b3-4697-8fc6-2a37fc524431

Li, Xuan Zhong, Webb, Jeremy S., Kjelleberg, Staffan and Rosche, Bettina (2006) Enhanced benzaldehyde tolerance in zymomonas mobilis biofilms and the potential of biofilm applications in fine-chemical production. Applied and Environmental Microbiology, 72 (2), 1639-1644. (doi:10.1128/AEM.72.2.1639-1644.2006).

Record type: Article

Abstract

Biotransformation plays an increasingly important role in the industrial production of fine chemicals due to its high product specificity and low energy requirement. One challenge in biotransformation is the toxicity of substrates and/or products to biocatalytic microorganisms and enzymes. Biofilms are known for their enhanced tolerance of hostile environments compared to planktonic free-living cells. Zymomonas mobilis was used in this study as a model organism to examine the potential of surface-associated biofilms for biotransformation of chemicals into value-added products. Z. mobilis formed a biofilm with a complex three-dimensional architecture comprised of microcolonies with an average thickness of 20 ?m, interspersed with water channels. Microscopic analysis and metabolic activity studies revealed that Z. mobilis biofilm cells were more tolerant to the toxic substrate benzaldehyde than planktonic cells were. When exposed to 50 mM benzaldehyde for 1 h, biofilm cells exhibited an average of 45% residual metabolic activity, while planktonic cells were completely inactivated. Three hours of exposure to 30 mM benzaldehyde resulted in sixfold-higher residual metabolic activity in biofilm cells than in planktonic cells. Cells inactivated by benzaldehyde were evenly distributed throughout the biofilm, indicating that the resistance mechanism was different from mass transfer limitation. We also found that enhanced tolerance to benzaldehyde was not due to the conversion of benzaldehyde into less toxic compounds. In the presence of glucose, Z. mobilis biofilms in continuous cultures transformed 10 mM benzaldehyde into benzyl alcohol at a steady rate of 8.11 g (g dry weight)?1 day?1 with a 90% molar yield over a 45-h production period

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Published date: August 2006

Identifiers

Local EPrints ID: 186821
URI: http://eprints.soton.ac.uk/id/eprint/186821
ISSN: 0099-2240
PURE UUID: ae87f790-fd44-429d-b389-c886a4bd9292
ORCID for Jeremy S. Webb: ORCID iD orcid.org/0000-0003-2068-8589

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Date deposited: 18 May 2011 13:53
Last modified: 15 Mar 2024 03:26

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Contributors

Author: Xuan Zhong Li
Author: Jeremy S. Webb ORCID iD
Author: Staffan Kjelleberg
Author: Bettina Rosche

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