hydrogen production and diversity of two microbial communities

hydrogen production and diversity of two microbial communities

HYDROGEN PRODUCTION AND DIVERSITY OF TWO MICROBIAL
COMMUNITIES USING CRYSTALLINE CELLULOSE AS SOLE SUBSTRATE
Alamilla-Ortiz ZL1, Escalante-Hernández AE2, Hernández-Guzmán G3, Valdez-Vazquez I4*
1
Posgrado en BioCiencias, División de Ciencias de la Vida, Universidad de Guanajuato, Ex–Hacienda El Copal Km
9 Carretera Irapuato-Silao. C.P. 36500 Irapuato, Gto.
2
Instituto de Ecología, UNAM, Ciudad Universitaria Coyoacán C.P. 04510, México D.F.
3
División de Ciencias de la Vida, Universidad de Guanajuato, Ex–Hacienda El Copal Km 9 Carretera Irapuato-Silao
A.P. 311 C.P. 36500 Irapuato, Gto.
4
Unidad Académica Juriquilla, Instituto de Ingeniería, UNAM, Juriquilla, Querétaro, Qro; C.P. 76230 México.
email: [email protected]
Abstract
Fermentative H2 production performed by microbial communities (MC) has several advantages such as high
production rates, use of non-sterile conditions, and possibility of using simple or complex substrates such as
lignocellulosic biomass. Lignocellulosic biomass (LB) is the most abundant renewable biomass on Earth, has a high
potential for its bioconversion into H 2 since it contain until 70 % of polysaccharides in form of cellulose and
hemicellulose. BL is distinguished by being refractory to physicochemical and enzymatic treatments, its efficient
conversion is only reached when complex MC are used. To this respect, heat-shock pretreatment (HSP) is commonly
applied to inocula to select H2 producers, however the MC's ability to degrade BL could be reduced since their
diversity is seriously affected. The aim of this study was to study the effects of the HSP on the H 2 production rate and
microbial diversity when crystalline cellulose as used as the sole carbon source. To this end, cow manure and heatshock pretreated cow manure (24 h/105 °C) were used as inoculum for H 2 production in 500 mL reactors with 10 g/L
of cellulose. These reactors were operated in batch mode with an initial pH of 7.0 and incubated statically at 55 °C.
Diversity of eubacteria, fungi and arquea were studied by confocal laser scanning microscopy and 454
pyrosequencing.