Wednesday, May 4, 2011: 7:35 PM
Grand Ballroom A, 2nd fl (Sheraton Seattle)
David N. Bryant1, Stephen M. Morris2, Dave Leemans1, Steve Fish1, Stephen Taylor3, John Carvel3, Naroa Garcia4, Andrew Ellis4 and Joe A. Gallagher1, (1)Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystywth, United Kingdom, (2)Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom, (3)Aber Instruments Ltd, Aberystwyth, United Kingdom, (4)Institute of Biological, Environmental and Rural Sciences, Biocatalysts Ltd, Cardiff, United Kingdom
In the UK, grasslands occupy ca. 70% of the total agricultural land area with 38% classed as permanent (pasture). Forage grasses such as perennial rye-grass (PRG) (
Lolium perenne) have been bred to give improved yields, ruminant digestibility and nitrogen use efficiency. This has been achieved through reduced lignin (<5% DM) and increased water soluble carbohydrate (>25% DM). As such, forage grasses, harvested in their vegetative state, could provide a valuable biorefining feedstock. Key to a lignocellulosic based biorefining process is the optimisation of fibre breakdown.
Dielectric annular spectroscopy (DAS) is routinely used in yeast and mammalian fermentations to quantitatively monitor viable biomass through the inherent capacitance of live cells. Previous work had demonstrated that the fibre fraction of PRG also exhibited an inherent capacitance which decreased during saccharification. The aim of the current study was to examine the application of DAS to PRG fibre saccharification in controlled bioreactors and correlate the output to HPLC analytical data.
The work presented here demonstrates that DAS is capable of both monitoring the on-line decrease in PRG fibre capacitance (at 580 kHz and 3362 kHz) while undergoing enzymatic hydrolysis together with the subsequent increase in capacitance due to the growth of a strain of B. coagulans. Transformation of the frequency data enabled the isolation of the decreasing capacitance signal associated with hydrolysis, which was in good agreement with sugar release data determined by HPLC. The data clearly show the utility of DAS probes for on-line monitoring of simultaneous saccharification and fermentations (SSF).
