A MEDIUM OPTIMIZATION STRATEGY FOR IMPROVEMENT OF GROWTH AND METHANE PRODUCTION BY METHANOBACTERIUM-THERMOAUTOTROPHICUM

Citation
G. Bretler et Iw. Marison, A MEDIUM OPTIMIZATION STRATEGY FOR IMPROVEMENT OF GROWTH AND METHANE PRODUCTION BY METHANOBACTERIUM-THERMOAUTOTROPHICUM, Journal of biotechnology, 50(2-3), 1996, pp. 201-212
Citations number
25
Categorie Soggetti
Biothechnology & Applied Migrobiology
Journal title
ISSN journal
01681656
Volume
50
Issue
2-3
Year of publication
1996
Pages
201 - 212
Database
ISI
SICI code
0168-1656(1996)50:2-3<201:AMOSFI>2.0.ZU;2-7
Abstract
Methanobacterium thermoautotrophicum, strain Hveragerdi, has been cult ivated in a completely defined mineral salts medium, under strictly an aerobic conditions with CO2 and H-2 as sole carbon and energy source, respectively. During optimization of the medium an iron limitation was identified that could not be overcome by the simple addition of iron- -or iron complexed with nitrilotriacetate (NTA)--to the medium, due to the formation of insoluble FeS complexes. In order to define a medium optimization strategy, and to avoid laborious empirical optimization procedures, a theoretical model has been developed in order to describ e the solubility of iron and other mineral species in the medium as a function of the concentration of sulfur and NTA. This model may be app lied for the optimization of any medium component. With this informati on sulfide has been replaced by a combination of cysteine and thiosulp hate in conjunction with a non-toxic reducing agent (titanium (III) ci trate). Using this defined medium precipitation was avoided and an iro n limitation was overcome resulting in a 5-fold improvement of the fin al biomass concentration from 2-3 g l(-1) to 11.2 g l(-1) together wit h a 2-fold increase (from 45 to almost 100%) in the conversion of CO2 and H-2 to CH4, even at gas flow rates as high as 6 1 min(-1).