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.