title: Alkaline conditions stimulate the production of 1,3-propanediol in Lactobacillus panis PM1 through shifting metabolic pathways.
abstract: A novel Lactobacillus panis PM1 isolate was found to be capable of converting glycerol to 1,3-propanediol (1,3-PDO), an increasingly valuable commodity chemical. In this study the effects of various process parameters, including glucose and glycerol concentrations, inoculum size, temperature, aeration, pH, and carbon source were examined to determine the optimal conditions for the production of 1,3-PDO using a culture method simulating late log to early stationary phases. Inoculum size did not influence the production of 1,3-PDO, and temperature variance showed similar 1,3-PDO production between 25 and 37 °C under the examined conditions. Glycerol concentration and pH played a primary role in the final concentration of 1,3-PDO. The highest production occurred at 150-250 mM glycerol when 50 mM glucose was available. Alkaline initial conditions (pH 9-10) stimulated the production of 1,3-PDO which concurrently occurred with increased acetic acid production. Under these conditions, 213.6 mM of 1,3-PDO were produced from 300 mM glycerol (conversion efficiency was 71 %). These observations indicated that the production of 1,3-PDO was associated with the shift of the metabolic end-product ethanol to acetic acid, and that this shift resulted in an excess concentration of NADH available for the processing of glycerol to 1,3-PDO.
authors: Food and Bioproduct Sciences, College of Agriculture and Bioresources, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8, Canada.
authors: Douglas A S
authors: DA
authors: Grahame
authors: Tae Sun
authors: TS
authors: Kang
authors: Nurul H
authors: NH
authors: Khan
authors: Takuji
authors: T
authors: Tanaka
mesh_terms: D058491:Bacterial Load; D001711:Biotransformation; D002244:Carbon / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry*; D005990:Glycerol / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007778:Lactobacillus / Q000187:drug effects* / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D010100:Oxygen / Q000378:metabolism; D011409:Propylene Glycols / Q000378:metabolism*; D013696:Temperature
chemical_list: D003470:Culture Media; D011409:Propylene Glycols; C041787:1,3-propanediol; D002244:Carbon; D005990:Glycerol; D010100:Oxygen
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