Investigation of Whole Genome Phylogeny and Genetic Analysis of Cyclic Lipopeptide Biosynthesis Genes in Antagonistic Strains of Bacillus
Total Page:16
File Type:pdf, Size:1020Kb
Investigation of Whole Genome Phylogeny and Genetic Analysis of Cyclic Lipopeptide Biosynthesis Genes in Antagonistic Strains of Bacillus by Emma Groulx A thesis submitted to the Faculty of Graduate and Postdoctoral Affairs in partial fulfillment of the requirements for the degree of Master of Science in Biology To Carleton University Ottawa, Ontario © 2017 Emma Groulx Acknowledgements I would first like to thank Dr. Myron Smith and Dr. Tyler J. Avis for being my co- supervisors and providing me with support and guidance throughout my graduate studies. I greatly appreciate the opportunity to continue my education and gain more research experience. Special thanks go out to Dr. Alex Wong and Dr. Nicolas Rodrigue for their guidance and assistance in data analysis and interpretation of results. I would like to thank Prabhjeet Basra for assistance with sequencing protocols and assessment of sequencing data. I would also like to thank Thomas Bujaki for technical assistance and for emotional support over the past two years. Lastly, I would like to thank all my family and friends who supported me throughout my graduate years. ii Abstract Disease suppressive composts and soil were found to contain bacteria belonging to the genus Bacillus that were antagonistic to plant pathogens. It is known that these species of bacteria produce antimicrobial compounds called cyclic lipopeptides. These bacteria produce three families of lipopeptides (surfactins, fengycins and iturins), however not all the isolates produce all of the lipopeptides. The genetics behind the production of these lipopeptides is not as well known. The objective of this study was to confirm the identity of the bacterial isolates using whole genome phylogeny and identify the Bacillus cyclic lipopeptide biosynthesis genes. Fifteen isolates of Bacillus subtilis, two isolates of B. megaterium and one isolate each of B. badius and Brevibacillus borstelensis were sequenced using an Illumina Miseq system and phylogenetic analysis was performed using protein-coding alignments. The cyclic lipopeptide genes were identified using nucleotide and protein blasts. It was shown that the identity of the bacterial isolates resembled the identity assigned using 16S rRNA sequences, with the exception of B. subtilis isolates CU12 and M9-3. It was also determined that the B. subtilis isolates and the B. borstelensis isolate possessed the gene operons for the cyclic lipopeptides whereas B. megaterium and B. badius isolates did not. Key Words: Bacillus, biocontrol, Brevibacillus, cyclic lipopeptides, phylogenetics. iii Table of contents Acknowledgements ......................................................................................................................... ii Abstract .......................................................................................................................................... iii Table of contents ............................................................................................................................ iv List of tables ................................................................................................................................... vi List of figures ............................................................................................................................... viii Chapter 1: Introduction ................................................................................................................... 1 1.1. Food security .................................................................................................................... 1 1.2. Fungicides ........................................................................................................................ 1 1.3. Biological control ............................................................................................................. 2 1.4. Composts as sources of microbial control agents ............................................................ 3 1.5. Bacillus and related bacteria ............................................................................................ 3 1.5.1. Bacillus .......................................................................................................................... 3 1.5.2. Brevibacillus .................................................................................................................. 4 1.6. Cyclic lipopeptides ........................................................................................................... 5 1.6.1. Surfactin......................................................................................................................... 6 1.6.2. Iturin .............................................................................................................................. 6 1.6.3. Fengycin ........................................................................................................................ 7 1.6.4. Nonribosomal peptide synthetases of Bacillus cyclic lipopeptides ............................... 8 1.7. Species identification ....................................................................................................... 9 1.8. Objectives and hypotheses ............................................................................................. 11 1.8.1. Objectives .................................................................................................................... 11 1.8.2. Hypotheses................................................................................................................... 11 Chapter 2: Materials and methods ................................................................................................ 12 2.1. Bacteria material ................................................................................................................ 12 2.2. Whole-genome sequencing and assembly.......................................................................... 13 2.3. Multiple sequence alignment and phylogenetic analysis ................................................... 14 2.4. Identification of CLP genes................................................................................................ 15 iv Chapter 3: Results ......................................................................................................................... 17 3.1. General assembly statistics................................................................................................. 17 3.2. Phylogenetic analysis ......................................................................................................... 18 3.2.1. Brevibacillus phylogenetic relationships ..................................................................... 18 3.2.2. Bacillus phylogenetic relationships ............................................................................. 20 3.3. BLAST analysis of cyclic lipopeptide biosynthesis genes ................................................ 23 Chapter 4: Discussion ................................................................................................................... 27 4.1. Evaluation of phylogenetic relationships of Bacillus and Brevibacillus isolates ............... 27 4.2. Evaluation of CLP biosynthesis genes ............................................................................... 31 4.3. Future work ........................................................................................................................ 40 Chapter 5: Conclusion................................................................................................................... 41 Chapter 6: References ................................................................................................................... 42 Appendixes ................................................................................................................................... 55 v List of tables Table 1: Identity and source of bacteria isolates from compost material ................................ 12 Table 2: Reference genomes in Bacillus phylogenetic tree, obtained from NCBI ................. 14 Table 3: Reference genomes in Brevibacillus phylogenetic tree, obtained from NCBI ......... 15 Table 4: Statistics for the Bacillus and Brevibacillus genome assemblies ............................. 17 Table 5: Summary of nucleotide BLAST hits of CLP genes in bacterial isolates .................. 25 Table 6: Summary of nucleotide and protein BLAST results for CLP genes in bacterial isolates ……………………………………………………………………………………... 26 Table 7: Cyclic lipopeptides produced and presence of CLP genes by bacterial isolates ...... 35 Table A1: Nucleotide and protein BLAST results of CLP genes for Bacillus subtilis isolate B9-1 …................................................................................................................................ 56 Table A2: Nucleotide and protein BLAST results of CLP genes for Bacillus subtilis isolate B9-5 .................................................................................................................................... 57 Table A3: Nucleotide and protein BLAST results of CLP genes for Bacillus subtilis isolate B9-7 .................................................................................................................................... 58 Table A4: Nucleotide and protein BLAST results of CLP genes for Bacillus subtilis isolate B9-8 ...................................................................................................................................