Effect of Temporal Sample Preservation on the Molecular Study of a Complex Microbial Community in the Gut of the Termite Microcerotermes sp.

Abstract

We investigated the effect of preserving samples with ethanol and acetone on molecular analyses of a complex microbial community in the gut of the termite Microcerotermes sp. Although the yield of DNA extracted from the guts decreased as the period of preservation increased (three days, one week, and one month), terminal-restriction fragment length polymorphism (T-RFLP) profiles of bacterial 16S rRNA genes amplified from the extracted DNA were conserved with respect to the occurrence of major taxa. Bacterial diversity detected in the analyses decreased only slightly after the preservation, and an analysis of clones demonstrated that the difference in terms of coverage was statistically insignificant before and one month after preservation with acetone, the treatment which resulted in the greatest dissimilarity in T-RFLP. However, the relative abundance of some taxonomic groups was remarkably changed after one month of preservation, especially in acetone. The results suggest that both ethanol and acetone well preserve bacterial DNA from a complex gut community, but that the DNA should be extracted as soon as possible. If the period of preservation exceeds one week, the molecular community profiles should be interpreted with caution, and it is better to avoid abundance-based comparisons.