title: Enhanced 1,3-propanediol production by a newly isolated Citrobacter freundii strain cultivated on biodiesel-derived waste glycerol through sterile and non-sterile bioprocesses.
abstract: The production of 1,3-propanediol (PD) by a newly isolated Citrobacter freundii strain [FMCC-B 294 (VK-19)] was investigated. Different grades of biodiesel-derived glycerol were employed. Slightly lower PD biosynthesis was observed in batch experiments only when crude glycerol from waste-cooking oil trans-esterification was utilized and only at elevated initial substrate concentrations employed. Batch bioreactor cultures revealed the capability of the strain to tolerate elevated amounts of substrate (glycerol up to 170 g/L) and produce quantities of PD in such high substrate concentrations. Nevertheless, maximum PD quantities (45.9 g/L) were achieved at lower initial glycerol concentrations (∼100 g/L) employed, suggesting some inhibition exerted due to the increased initial substrate concentrations. In order to improve PD production, a fed-batch fermentation was carried out and 68.1g/L of PD were produced (the highest PD quantity achieved by C. freundii strains so far) with yield per glycerol consumed ∼0.40 g/g and volumetric productivity 0.79 g/L/h. Aiming to perform a more economical and eco-friendlier procedure, batch and fed-batch fermentations under completely non-sterile conditions were carried out. During non-sterilized fed-batch process, 176 g/L of raw glycerol were converted to 66.3g/L of PD, suggesting the potentiality of the non-sterile fermentation by C. freundii FMCC-B 294.
authors.affiliation: Department of Food Science and Technology, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Metsoviti
authors.forename: An-Ping
authors.initials: AP
authors.lastname: Zeng
authors.forename: Apostolis A
authors.initials: AA
authors.lastname: Koutinas
authors.forename: Seraphim
authors.initials: S
authors.lastname: Papanikolaou
mesh_terms: D061249:Batch Cell Culture Techniques; D056804:Biofuels; D019149:Bioreactors; D001709:Biotechnology / Q000379:methods*; D016971:Citrobacter freundii / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D003470:Culture Media; D005285:Fermentation; D005990:Glycerol / Q000378:metabolism*; D011409:Propylene Glycols / Q000378:metabolism*; D013242:Sterilization
chemical_list: D056804:Biofuels; D003470:Culture Media; D011409:Propylene Glycols; C041787:1,3-propanediol; D005990:Glycerol