Year

2018

Season

Summer

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

First Advisor

Dr. Dale Casamatta

Second Advisor

Dr. Anthony Rossi

Third Advisor

Dr. Judith Ochrietor

Fourth Advisor

Mrs. Amy Keagy

Department Chair

Dr. Cliff Ross

College Dean

Dr. George Rainbolt

Abstract

Cyanobacteria are a group of photo-oxygenic bacteria found in nearly every ecosystem, but much cyanobacterial diversity, in various habitats, has yet to be explored. Cyanobacteria are often conspicuous components of photosynthetic flora, providing significant carbon and nitrogen inputs to surrounding systems. As possible primary colonizers of stone substrates not native to this region, cyanobacteria isolated from headstones may provide biogeographically informative data. An exploratory study of lichen-dominated microbial consortia, growing on headstones, was conducted to isolate and identify novel microaerophytic cyanobacteria, and resulted in the establishment of four novel cyanobacterial taxa. Phylogenetic analyses of photobionts in one tripartite lichen revealed two novel taxa: Brasilonema lichenoidesand Chroococcidiopsis lichenoides. Using a total evidence approach, analyzing ecology, morphology, ITS structure, and molecular data two additional taxa were described: Brasilonema geniculosusand Calothrix dumas. Analysis of secondary structures of the Internal Transcribed Spacer (ITS) regions of the 16S-23S operon in cyanobacteria are commonly used in cyanobacterial taxonomy studies and were applied to the identification of the new taxa in this study. However, the relationship between ITS structures, hairpin loops (helices) in a region of non-coding DNA, has not been thoroughly evaluated. The 16S-23S operon is one of many in prokaryotes with multiple copies and there is evidence that operons may vary due to differential selective pressures or drift. A study was undertaken analyzing ITS operons from 224 previously published cyanobacterial taxa for domain inclusion and exclusion, intragenomic heterogeneity of ITS operons, and the possible relevance of variable selective pressures affecting individual domains. Analysis revealed highly variable ITS domain inclusion even in complete sequences, as well as high variation between domains containing two or no tRNA sequences. Recommendations were made to standardize ITS analysis in the future to account for this possible variation. Further study is required to statistically demonstrate to what extent ITS secondary structures correlate with taxonomy.

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