Bioaugmented hydrogen production from carboxymethyl cellulose and partially delignified corn stalks using isolated cultures

Dark fermentation of carboxymethyl cellulose to produce biohydrogen using mono-culture or co-culture of isolated strains was studied. Three isolates were noted to effectively hydrolyze cellulosic substrates and degrade the metabolites to hydrogen and volatile fatty acids. The strain Clostridium acetobutylicum X₉ was noted to have the highest hydrogen yield amongst the three isolates in all tests. Co-cultures of any two of the three isolates and with another strain Ethanoigenens harbinense B₄₉ demonstrated higher biohydrogen yield and cellulose hydrolysis ratio compared with the mono-cultured tests. Bioaugmentation with co-cultures X₉ + B₄₉ efficiently improved cellulose hydrolysis and subsequent hydrogen production rates from carboxymethyl cellulose. The strain X₉ significantly hydrolyzed corn stalks pretreated with H₂SO₄, NaOH, and NH₃ soaking, and steam explosion in 10-12 h. Hydrogen was yielded in conjunction with the noted cellulose hydrolysis. The steam explosion + hydrolysis/fermentation with X₉ present the most effective method amongst the four tested pretreatments for hydrolyzing cellulose and yielding hydrogen. © 2008 International Association for Hydrogen Energy.