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A voyage to finding unculturable acidobacteriota from fynbos and arid regions in South Africa
Thesis (PhD)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1867613768296431616 |
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| access_status_str | Open Access |
| author | Pieters, Janca |
| author2 | Jacobs, Karin |
| author_browse | Jacobs, Karin Pieters, Janca |
| author_facet | Jacobs, Karin Pieters, Janca |
| author_sort | Pieters, Janca |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/134775 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:41:23.238Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/134775 A voyage to finding unculturable acidobacteriota from fynbos and arid regions in South Africa Pieters, Janca Jacobs, Karin Ter Haar, Tersia A. Stellenbosch University. Faculty of Science. Dept. of Microbiology. Fynbos -- South Africa -- Geographical distribution Acidobacteriota -- Genetics Soil microbiology -- South Africa Arid regions ecology -- South Africa Bacteria -- Cultures and culture media High-throughput nucleotide sequencing UCTD Thesis (PhD)--Stellenbosch University, 2025. Pieters, J. 2025. A voyage to finding unculturable Acidobacteriota from Fynbos and Arid regions in South Africa. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/1862c5df-d49f-4754-8558-dd1a072813e9 ENGLISH ABSTRACT: Acidobacteriota is a highly abundant and diverse bacterial phylum that dominates many ecosystems, particularly soils, where it can constitute up to 50 % of the total bacterial community. Despite their widespread presence, only a small number of species have been formally described since the phylum’s discovery three decades ago, with most remaining uncultured or difficult to cultivate. Their high abundance suggests a significant role in biogeochemical cycles and ecosystem processes, particularly in nutrient-poor soils, where microbial activity supports plant growth and ecosystem stability. This is especially relevant in arid lands, which cover approximately 40 % of Earth's land surface. In South Africa, the Nama Karoo, spanning over 135,000 km², represents one such environment where microbial communities are critical for maintaining soil fertility and ecosystem resilience in response to climate change and shifting precipitation patterns. Another key region is the Cape Floristic Region (CFR), a biodiversity hotspot home to many endemic and critically endangered species. Despite extensive research, the role of Acidobacteriota in these ecosystems remains understudied. This study aimed to explore Acidobacteriota communities in the Nama Karoo and fynbos soils of the CFR using next-generation sequencing techniques, while also isolating and taxonomically characterising novel species. A meta-analysis was conducted on all currently available data on microbial diversity alongside soil physicochemical properties in Southern African semi-arid soils to provide an overview of the current knowledge of Acidobacteriota in these environments (Chapter 2). To further expand our understanding, three locations in the Nama Karoo were selected for study (Chapter 2). In this region, 96 bulk soil samples were collected, revealing Acidobacteriota relative abundances ranging from 2.3 % to 12.17 %, with Subdivisions 3, 4, and 6 being dominant. Location-specific subdivisions, such as SD 9 and SD 2, suggested localised environmental influences, while SD 17 and SD 25 clustered together, indicating shared ecological preferences. Certain abiotic factors significantly influenced distribution patterns, highlighting specific adaptations of particular subdivisions to environmental conditions. Additionally, co-occurrence analyses revealed interactions between Acidobacteriota, Planctomycetota, and Armatimonadota, suggesting potential biofilm formation and shared environmental niches. In the CFR, 26 bulk soil samples were collected, revealing Acidobacteriota relative abundances ranging from 1.5 % to 36.25 %, with Subdivision 1 being the most dominant (Chapter 3). Notably, this study reported the first detection of Subdivisions 22 and 17 in fynbos soils. Significant community composition differences were observed, driven by soil pH, moisture content, available phosphate, electrical conductivity, and enzyme activity. In addition, a novel Acidobacteriota genus, Dedyshia gen. nov., with the type strain Dedyshia acidiphila sp. nov., was successfully isolated and taxonomically characterised (Chapter 4). Genomic analysis revealed genes for complete carbohydrate metabolic pathways, nitrogen metabolism, stress and survival-response mechanisms all of which contribute to its survival in soil environments. This study provides valuable insights into the diversity, distribution, and ecological roles of Acidobacteriota in South Africa's semi-arid ecosystems and Fynbos Biome. Furthermore, the successful isolation of a novel genus contributes to expanding global knowledge of cultivated Acidobacteriota, shedding light on their functional adaptations and ecological significance. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Doctoral 2026-01-07T10:34:46Z 2026-01-07T10:34:46Z 2025-12 Thesis https://scholar.sun.ac.za/handle/10019.1/134775 Stellenbosch University xvii, 162 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Fynbos -- South Africa -- Geographical distribution Acidobacteriota -- Genetics Soil microbiology -- South Africa Arid regions ecology -- South Africa Bacteria -- Cultures and culture media High-throughput nucleotide sequencing UCTD Pieters, Janca A voyage to finding unculturable acidobacteriota from fynbos and arid regions in South Africa |
| title | A voyage to finding unculturable acidobacteriota from fynbos and arid regions in South Africa |
| title_full | A voyage to finding unculturable acidobacteriota from fynbos and arid regions in South Africa |
| title_fullStr | A voyage to finding unculturable acidobacteriota from fynbos and arid regions in South Africa |
| title_full_unstemmed | A voyage to finding unculturable acidobacteriota from fynbos and arid regions in South Africa |
| title_short | A voyage to finding unculturable acidobacteriota from fynbos and arid regions in South Africa |
| title_sort | voyage to finding unculturable acidobacteriota from fynbos and arid regions in south africa |
| topic | Fynbos -- South Africa -- Geographical distribution Acidobacteriota -- Genetics Soil microbiology -- South Africa Arid regions ecology -- South Africa Bacteria -- Cultures and culture media High-throughput nucleotide sequencing UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/134775 |
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