Influence of gaseous end-products inhibition and nutrient limitations on the growth and hydrogen production by hydrogen-producing fermentative bacterial B49

Hydrogen-producing bacterial strain B49 (HPB B49, AF481148 in EMBL) was grown in a synthetic medium with glucose as substrate, enabling the precise quantification of each nutrientʹs contribution to growth. Hydrogen production had a correlation with cell growth and the consumption of glucose and soluble protein. Liquid end-products of fermentation, predominantly ethanol, acetate and in minor amounts lactate, accumulated in the medium. Gaseous end-products comprised hydrogen and carbon dioxides. Growth of the bacterium in fresh media sparged with hydrogen and carbon dioxide showed that the hydrogen partial pressure in the fermentor had no influence on the growth rate and hydrogen production, however, the carbon dioxide affected the hydrogen fermentation and growth of HPB B49. As regards nutrients, iron and magnesium ion could induce metabolic change and affect the growth and the hydrogen production by HPB B49.