Master of Science (MS)
The Formosan subterranean termite (FST), a pest species native to China and introduced to the U.S., is obligatorily dependent on its gut microbiota. Using high-throughput 16S rRNA gene sequencing, the effects of long-term alcohol storage and geographic location on the bacteria composition of the FST colonies were investigated. Initial studies found the use of amplified ribosomal DNA restriction analysis (ARDRA) to be unpractical due to its higher costs compared to the direct sequencing of 16S rRNA gene sequences. Using nine FST colonies consisting of fresh and alcohol-stored Lousiana FST colonies and alcohol-stored China FST colonies, 237 bacteria ribotypes were identified from 1876 clones based on a <97% sequence similarity criterion. Twenty-four of the ribotypes were artifact sequences and were excluded from subsequent analyses. Most of the remaining ribotypes were novel (70.89% of total ribotypes). Termite-specific bacteria dominated the bacteria composition in the FSTs (66.45% of total clones). Only 3.34% of the total clones were similar to environmental bacteria. Thirteen bacteria phyla were represented: Bacteroidetes (42.91% of total clones), Firmicutes (30.49%), Spirochaetes (11.30%), Actinobacteria (5.70%), Proteobacteria (2.24%), Tenericutes (1.55%), candidate division Termite Group 1 (1.01%), candidate division TM7 (0.64%), Verrucomicrobia (0.59%), Planctomycetes (0.48%), candidate division Synergistes (0.21%), candidate division ZB3 (0.05%) and Cyanobacteria (0.05%). The Bacteroidetes ribotype previously identified to be dominant in FST from Japan, was also among the dominant phyla in all the FST colonies of this study (38.71% of total clones). Differential DNA degradation occurred in the alcohol-stored FST samples, leading to higher proportions of the gram-positive bacteria such as Actinobacteria, Bacilli and Clostridia and lower proportions of the gram-negative bacteria such as Bacteroidetes and Spirochaetes compared to the fresh FST samples. Long-term alcohol storage of the FST led to the discovery of less abundant ribotypes when the predominant ribotype was reduced. Geographic region did not show detectable influence on the FST bacteria composition. This was likely due to the multiple introduction of FST from China into the U.S. Future studies using T-RFLP to sample the bacteria community from FST colonies randomized across each geographical region would be useful in confirming the observations from this study.
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Ho, Huei-Yang, "Comparisons of bacterial community within the abdomens of Formosan subterranean termites, fresh- and alcohol-stored, from their native (China) and introduced (U.S.) range" (2008). LSU Master's Theses. 3982.