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

Abstract

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 X 9 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 B 49 demonstrated higher biohydrogen yield and cellulose hydrolysis ratio compared with the mono-cultured tests. Bioaugmentation with co-cultures X 9 + B 49 efficiently improved cellulose hydrolysis and subsequent hydrogen production rates from carboxymethyl cellulose. The strain X 9 significantly hydrolyzed corn stalks pretreated with H 2SO 4, NaOH, and NH 3 soaking, and steam explosion in 10–12 h. Hydrogen was yielded in conjunction with the noted cellulose hydrolysis. The steam explosion + hydrolysis/fermentation with X 9 present the most effective method amongst the four tested pretreatments for hydrolyzing cellulose and yielding hydrogen.