Two-stage fungal biopulping for improved enzymatic hydrolysis of wood

Peculiarities of brown-rot fungi and biochemical Fenton reaction with regard to their potential as a model for bioprocessing biomass

“…In this context, a bio-mimetic brownrot non-enzymatic system (Goodell et al 2000) as well as a complete brown-rot fungus biopulping treatment (Ray and Murphy 2011) has been proposed for use in lignocellulytic depolymerization for industrial applications to improve monomeric sugar solubilization. A limited (but increasing) number of studies have recently shown a significant improvement in the enzymatic hydrolysis yield of monomeric sugars from brown-rot fungus-biopulped lignocellulosic materials (Giles et al 2011;Schilling et al 2009;Monrroy et al 2011). However, studies demonstrating that such biological pretreatment offers technical and economic advantages over other forms of pretreatment do not exist.…”

Single versus simultaneous species treatment of wood with Ceriporiopsis subvermispora and Postia placenta for ethanol applications, with observations on interspecific growth inhibition

“…Single stage biopulping was performed using modification of previously described techniques (Giles et al, 2011, Giles et al 2012a, Giles et al, 2012b. Prior to inoculation onto wood, C. subvermispora and P. placenta isolates were subcultured in low nitrogen malt extract agar (20 g malt extract, 20 g agar L À1 in deionized water) at 28 C for 7e10 d. A fungal plug from the malt extract agar plate of each species was then placed in 500 mL of low nitrogen malt extract liquid medium (20 g malt extract L À1 in deionized water) and incubated at 28 C for 7e10 d. For each treatment, 1 g (oven dry weight) of wood chips was placed into 20 mL glass scintillation vials and distilled water was added to increase moisture content to 70%.…”

“…Recently, searches for low cost methods of biomass pretreatment have sparked interest in natural woody biomass degradation processes. One such process, generally referred to as "biopulping", utilizes living wholeorganism fungi as a low-energy pretreatment to degrade lignocellulosic biomass for industrial paper and/or potential biofuel production (P erez et al, 2002;Tortella et al, 2008;Vimala and Nilanjana, 2009;Giles et al, 2011Giles et al, , 2012a. Of particular interest are filamentous wood decay fungi belonging to the order Polyporales (within the phylum Basidiomycota), which are ecologically central in the breakdown and nutrient recycling of forest residues (i.e.…”

“…Depending upon biomass type and desired breakdown products, exposure to the respective lignolytic and cellulolytic activities of both white rot and brown rot fungi may also be useful as a biopulping strategy. Staged biopulping using successive exposures to white rot and/or brown rot fungi have recently been explored as methods for increasing carbohydrate availability for subsequent enzymatic hydrolysis into glucose (Lee et al, 2008;Giles et al, 2011Giles et al, , 2012a. While staged successive applications of both white and brown rot fungi have been found to significantly increase the sugar yield of enzymatic hydrolysis, the process requirements of staged fungal exposures have disadvantages that may impede commercial adoption.…”

“…While staged successive applications of both white and brown rot fungi have been found to significantly increase the sugar yield of enzymatic hydrolysis, the process requirements of staged fungal exposures have disadvantages that may impede commercial adoption. In particular, previous staged treatments required that the biomass be sterilized between fungal exposures, and each fungus required a minimum 30 day colonization period for effective biopulping (Giles et al, 2011). A potential but untested solution to minimize these energy (biomass sterilization) and time (~60 day) costs is simultaneous co-exposure of the biomass to both fungi at the same time.…”