title: Investigation of relationship between 2,3-butanediol toxicity and production during growth of Paenibacillus polymyxa.
abstract: Understanding the capacity of Paenibacillus polymyxa DSM 365 to tolerate increasing concentrations of 2,3-butanediol (2,3-BD) is critical to engineering a 2,3-BD-overproducing strain. Hence, we investigated the response of P. polymyxa to high 2,3-BD concentrations. In fed-batch cultures (6-L bioreactor) 2,3-BD was accumulated to a maximum concentration of 47g/L despite the presence of residual 13g/L glucose in the medium. Concomitantly, accumulation of acetoin, the precursor of 2,3-BD increased after maximum 2,3-BD concentration was reached, suggesting that 2,3-BD was reconverted to acetoin after the concentration tolerance threshold of 2,3-BD was exceeded. Cultures of P. polymyxa were then challenged with levo-2,3-BD (20, 40 and 60g/L) at 0h in a glucose medium, and a concentration dependent growth inhibition response to levo-2,3-BD was observed. The growth of P. polymyxa was completely inhibited by 60g/L levo-2,3-BD. Furthermore, P. polymyxa was challenged with incremental 2,3-BD concentrations (20, 40 and 60g/L at 12, 24 and 36h, respectively) to mimic 2,3-BD accumulation during fermentation. Interestingly, 2,3-BD was reconverted to acetoin when its concentration reached 60g/L, possibly to alleviate 2,3-BD toxicity. Collectively, our findings indicate that 2,3-BD-mediated toxicity is a major metabolic impediment to 2,3-BD overproduction, thus, making it an important metabolic engineering target towards rational design of a 2,3-BD-overproducing strain.
authors.affiliation: Department of Animal Sciences, The Ohio State University, and Ohio State Agricultural Research and Development Center (OARDC), 305 Gerlaugh Hall, 1680 Madison Avenue, Wooster, OH 44691, USA.
authors.forename: Christopher Chukwudi
authors.initials: CC
authors.lastname: Okonkwo
authors.affiliation: Renewable Energy Program, Agricultural Technical Institute, The Ohio State University, 1328 Dover Road, Wooster, OH 44691, USA.
authors.forename: Victor
authors.initials: V
authors.lastname: Ujor
authors.affiliation: Department of Animal Sciences, The Ohio State University, and Ohio State Agricultural Research and Development Center (OARDC), 305 Gerlaugh Hall, 1680 Madison Avenue, Wooster, OH 44691, USA. Electronic address: ezeji.1@osu.edu.
authors.forename: Thaddeus Chukwuemeka
authors.initials: TC
authors.lastname: Ezeji
mesh_terms: D000093:Acetoin / Q000378:metabolism; D061249:Batch Cell Culture Techniques; D056804:Biofuels; D019149:Bioreactors; D001709:Biotechnology; D002072:Butylene Glycols / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity*; D025461:Feedback, Physiological; D005285:Fermentation; D060847:Metabolic Engineering; D000070057:Paenibacillus polymyxa / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D013237:Stereoisomerism
chemical_list: D056804:Biofuels; D002072:Butylene Glycols; C026978:2,3-butylene glycol; D000093:Acetoin
keywords: 1,3- butadiene; Exopolysaccharide; Levo-2,3-butanediol; Paenibacillus polymyxa; acetoin