title: Long-term biological hydrogen production by agar immobilized Rhodobacter capsulatus in a sequential batch photobioreactor.
abstract: In this study, agar immobilization technique was employed for biological hydrogen production using Rhodobacter capsulatus DSM 1710 (wild type) and YO3 (hup-mutant) strains in sequential batch process. Different agar and glutamate concentrations were tested with defined nutrient medium. Agar concentration 4% (w/v) and 4 mM glutamate were selected for bacterial immobilization in terms of rate and longevity of hydrogen production. Acetate concentration was increased from 40 to 60-100 and 60 mM gave best results with both bacterial strains immobilized in 4% (w/v) agar. Cell concentration was increased from 2.5 to 5 mg dcw mL-1agar and it was found that increasing cell concentration of wild-type strain caused decrease in yield and productivity while these parameters improved by increasing cell concentration of mutant strain. Also, the hydrogen production time has extended from 17 days up to 60 days according to the process conditions and parameters. Hydrogen production by immobilized photosynthetic bacteria is a convenient technology for hydrogen production as it enables to produce hydrogen with high organic acid concentrations comparing to suspended cultures. Besides, immobilization increases the stability of the system and allowed sequential batch operation for long-term application.
authors.affiliation: Department of Biology and Biotechnology, Islamic University of Gaza, Gaza, Palestine.
authors.forename: Kamal
authors.initials: K
authors.lastname: Elkahlout
authors.affiliation: Department of Chemical Engineering, Middle East Technical University, 06800, Ankara, Turkey.
authors.forename: Siamak
authors.initials: S
authors.lastname: Alipour
authors.affiliation: Department of Chemical Engineering, Middle East Technical University, 06800, Ankara, Turkey.
authors.forename: Inci
authors.initials: I
authors.lastname: Eroglu
authors.affiliation: Department of Biology, Middle East Technical University, 06800, Ankara, Turkey.
authors.forename: Ufuk
authors.initials: U
authors.lastname: Gunduz
authors.affiliation: Department of Biology, Middle East Technical University, 06800, Ankara, Turkey. meraly@metu.edu.tr.
authors.forename: Meral
authors.initials: M
authors.lastname: Yucel
mesh_terms: D000362:Agar / Q000737:chemistry*; D019149:Bioreactors; D018914:Cells, Immobilized / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D016354:Rhodobacter capsulatus / Q000378:metabolism*; D013997:Time Factors
chemical_list: D006859:Hydrogen; D000362:Agar
keywords: Biological hydrogen production; Immobilizing bacteria; Photobioreactor; Rhodobacter capsulatus; Sequential batch process