The change in bacterial community structure during the anaerobic digestion of medium density fiberboard as determined by T-RFLP

Abstract

Medium Density Fiberboard (MDF) is a material commonly used to construct furniture and is an engineered product made up of wood particles bonded with the adhesive resin, urea-formaldehyde. In the presence of the resin, MDF is not recyclable; therefore, it is normally burned or thrown in a landfill. The compound is easily hydrolyzed into urea and formaldehyde that potentially leach toxins. However, it can be decontaminated with microorganisms under the anaerobic condition, converting the components into biogas such as methane, carbon dioxide, and renewable energy sources. This study aims to characterize the microbial community changes during the anaerobic degradation of MDF. Specifically, observing any decreased or increased key taxonomic groups of bacteria through out the period when MDF was being digested under anaerobic conditions, producing gases including methane and carbon dioxide. DNA extraction of the first sample (sample A) was solely from diluted cow manure, then additional samples (Sample B-D) were taken from an inoculum consisting of MDF, cow manure, and water. According to the general total gas production trend, time specific samples were selected for DNA extraction from samples B-D. DNA extraction of each sample was replicated to limit random bias. Then the PCR-amplified 16S rRNA target genes that belonged to different taxonomic groups were examined to study bacterial community structure and dynamics by using terminal restriction fragment length polymorphism (T-RFLP). Finally, Phylogenetic Assignment Tool (PAT) was used to interpret the peaks from the profile to identify the groups of bacteria community. As expected, there were changes in structure of microbial communities and it was characterized that there were close relationships between sample B and sample D that were located in the high rate of gas production.