Poster Presentation 2-22

Screening Bacterial Consortia from Wood Eating Insect Guts for Ligninase Activity

Aarti Gidh^1*, Dinesh Talreja², Clint Williford¹ and Alfred Mikell²

¹Department of Chemical Engineering

224 Anderson Hall

Chemical Engineering

University of Mississippi

University, MS 38677

Phone: (662) 915 5028

Fax: (662) 915 7023

Email: aartigidh@hotmail.com

²Department of Biology, University of Mississippi

Lignin is the second largest source of fixed carbon in the biosphere, but resists rapid biological degradation. Lignin due to its intimate association with cellulose and hemicellulose forms a barrier to enzymatic attack. Termites, beetles and other arthropods can digest decaying wood, grass, animal dung and other lignocellulosic plant litter. Lignin-degrading filamentous bacteria have been isolated from the termite gut. Bacterial lignin degradation has also been reported to be more specific than with fungal systems, an advantage for biotechnology applications.

Bacterial counts (CFU) and protein assay techniques were used to analyze and ensure optimum growth conditions for the bacteria from the dissected fore, mid and hindgut of Popilius disjunctus (Betsy Beetles). Drop plate technique was used with agar plates incubated under aerobic, microaerophilic and anaerobic conditions. Different types of media set-ups (pH) and nutrient compositions were also tried. Biological studies were conducted to identify the bacteria.

Batch studies (200 ml) with yeast malt extract (YM) media were also conducted in duplicate with the cultures grown from the anaerobic sludge. Changes in the molecular weight distribution of Kraft lignin (L) were tracked over 26 days with HPLC (UV detector). Lignin without YM showed only polymerization (increase in molecular weight). Initial pH was adjusted to 8, but declined with incubation for flasks containing yeast malt extract (YM, YM+L). The CFU showed increased growth for flasks with YM+L, compared to YM alone. Least growth was observed in cultures with only lignin.