SCREENING FOR MICROORGANISMS USEFUL IN DETOXIFICATION OF LIGNOCELLULOSIC HYDROLYSATES

Authors: LOPEZ, MARIA - UNIV ALMERIA, SPAIN; Nichols, Nancy; Dien, Bruce; MORENO, J - UNIV ALMERIA, SPAIN; Bothast, Rodney

Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/23/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Minimizing inhibitor effects is of utmost importance for efficient fermentation of lignocellulosic hydrolysates. Several methods of detoxification have been tried and include chemical and physical treatments. However, few biological approaches have been proposed. The aim of this work is to search for microorganisms able to deplete complex mixtures of inhibitors produced during the hydrolysis of lignocellulosic substrates. Soil samples were obtained from an industrial site, and sequential enrichments were used to isolate microorganisms with specific degradative activity. Initially, selection was carried out in a defined mineral medium (TM) containing ferulic acid (5 mM), 4-hydroxymethylfurfural (15 mM), and furfural (20 mM). A total of 29 strains were isolated after 4 transfers on TM. These strains grew on and/or were tolerant to ferulic acid, hydroxymethylfurfural, and furfural. An additional transfer was made einto a corn stover acid hydrolysate (AH), and nine strains were recovered. Subsequently, based on stable growth on a range of toxic compounds, six isolates (five bacteria and one fungus) were chosen. The isolates were identified by sequencing a portion of the small subunit rDNA as species of Flavobacterium, Pseudomonas, Acinetobacter, Methylobacterium, Arthrobacter, and Wallrothiella. These strains reduced the level of toxic compounds present in AH by 50 to 100% and may be useful in developing bioprocesses for inhibitor abatement in the conversion of lignocellulosic biomass to fuels and chemicals.