title: Continuous xylanase production with Aspergillus nidulans under pyridoxine limitation using a trickle bed reactor.
abstract: A trickle bed reactor (TBR) with recycle was designed and tested using Aspergillus nidulans with a pyridoxine marker and over-expressing/secreting recombinant client xylanase B (XynB). The pyridoxine marker prevented the fungus from synthesizing its own pyridoxine and fungus was unable to grow when no pyridoxine was present in the medium; however, enzyme production was unaffected. Uncontrolled mycelia growth that led to clogging of the TBR was observed when fungus without a pyridoxine marker was used for XynB production. Using the fungus with pyridoxine marker, the TBR was operated continuously for 18 days and achieved a XynB output of 41 U/ml with an influent and effluent flow rate of 0.5 ml/min and a recycle flow rate of 56 ml/min. Production yields in the TBR were 1.4 times greater than a static tray culture and between 1.1 and 67 times greater than yields for SSF enzyme production stated in the literature.
authors: Department of Biosystems Engineering, Oklahoma State University, 111 Agriculture Hall, Stillwater, OK 74078, USA. Electronic address: michael.mueller@pfi-biotechnology.de.
authors: Michael
authors: M
authors: Müller
authors: Department of Microbiology and Molecular Genetics, Oklahoma State University, 307 Life Sciences East, Stillwater, OK 74078, USA. Electronic address: rolf.prade@okstate.edu.
authors: Rolf A
authors: RA
authors: Prade
authors: Department of Microbiology and Molecular Genetics, Oklahoma State University, 307 Life Sciences East, Stillwater, OK 74078, USA.
authors: Fernando
authors: F
authors: Segato
authors: Department of Biosystems Engineering, Oklahoma State University, 111 Agriculture Hall, Stillwater, OK 74078, USA. Electronic address: hasan.atiyeh@okstate.edu.
authors: Hasan K
authors: HK
authors: Atiyeh
authors: Department of Biosystems Engineering, Oklahoma State University, 111 Agriculture Hall, Stillwater, OK 74078, USA. Electronic address: mark.wilkins@okstate.edu.
authors: Mark R
authors: MR
authors: Wilkins
mesh_terms: D001233:Aspergillus nidulans / Q000201:enzymology*; D018533:Biomass; D019149:Bioreactors; D003470:Culture Media / Q000737:chemistry; D043364:Endo-1,4-beta Xylanases / Q000096:biosynthesis*; D004867:Equipment Design; D005285:Fermentation; D005838:Genotype; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology / Q000379:methods; D011736:Pyridoxine / Q000737:chemistry*
chemical_list: D003470:Culture Media; D043364:Endo-1,4-beta Xylanases; D011736:Pyridoxine
keywords: Biomass; Bioreactors; Enzymes; Filamentous fungi