title: The effects of cell recycling on the production of 1,3-propanediol by Klebsiella pneumoniae.
abstract: The effects of both biomass age and cell recycling on the 1,3-propanediol (1,3-PDO) production by Klebsiella pneumoniae were investigated in a membrane-supported bioreactor using hollow-fiber ultrafiltration membrane module in two separate experiments. It was determined that older cells have a negative effect on 1,3-PDO production. The concentrations of by-products, such as acetic acid and ethanol, increased in cultures with older cells, whereas the concentrations of succinic acid, lactic acid and 2,3-butanediol decreased. The effect of cell recycling was comparatively studied at a cell recycling ratio of 100 %. The results showed that cell recycling had also negative effects on 1,3-PDO fermentation. It was hypothesized that both cell recycling and biomass age caused metabolic shifts to undesired by-products which then inhibited the 1,3-PDO production. On the other hand, the use of hollow-fiber ultrafiltration membrane module was found to be very effective in terms of removal of cells from the fermentation broth.
authors.affiliation: Bioengineering Department, Faculty of Engineering, Ege University, Bornova, 35100, Izmir, Turkey, gizemavci@gmail.com.
authors.forename: Fatma Gizem
authors.initials: FG
authors.lastname: Avci
authors.forename: Damla
authors.initials: D
authors.lastname: Huccetogullari
authors.forename: Nuri
authors.initials: N
authors.lastname: Azbar
mesh_terms: D018533:Biomass; D019149:Bioreactors; D005285:Fermentation; D007711:Klebsiella pneumoniae / Q000378:metabolism*; D008567:Membranes, Artificial; D011409:Propylene Glycols / Q000378:metabolism*; D014462:Ultrafiltration
chemical_list: D008567:Membranes, Artificial; D011409:Propylene Glycols; C041787:1,3-propanediol