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Doctoral Thesis
Ochre Archaeomicrobiology: Provenancing Australian Pigments through Microbial Fingerprinting Investigations into Sample Size and Temporal Variation
Murdoch University
Doctor of Philosophy (PhD), Murdoch University
2025
DOI:
https://doi.org/10.60867/00000081
Abstract
Ochre is an important component of many archaeological assemblages however the assignment of provenance remains a challenge due to its variable mineral composition and formation. While previous characterisations utilising elemental, chemical, and magnetic measurements have proven successful to provenance ochre, genomic strategies to date are under-explored. This project analysed the microbial profile of culturally significant ochre collected with Aboriginal Traditional Owners. Sites investigated included White Cockatoo (NT), Overland Corner (SA) and Tom Price (WA). This project had a trifold approach focusing on the analytical limits of ochre at differing input masses, the impacts of temporal events of bacterial diversity, and the overall ability to provenance ochre utilising bacterial means.
Over a three-year period, 308 ochre samples were collected under sterile conditions from selected sites across Australia. To assess temporal variation, repeat sampling was conducted at set intervals throughout the study period. Genetic material was optimised and purified from each sample using a solid-phase extraction protocol, and microbial community composition was characterised via 16S rRNA next-generation sequencing. Resulting sequence data were processed using the DADA2 pipeline to generate high-resolution bacterial profiles, which were subsequently used for statistical analysis.
While the iron content within ochre degrades the quality of the DNA sequence reads, the overall genetic profiles were sufficient for microbial analysis regardless of input weight. The resulting genetic profiles showed promise for the associated microbial provenance of archaeological materials, providing statistically significant site-based values for every location. The weather events experienced within the sites created significant changes within the alpha-diversity measures, the beta-diversity was unchanged, indicating that weather has no impact on the overall ability to provenance materials. This protocol can complement elemental and isotopic provenance analyses by adding more evidence to the ochre characterisation “fingerprint.”
Details
- Title
- Ochre Archaeomicrobiology: Provenancing Australian Pigments through Microbial Fingerprinting Investigations into Sample Size and Temporal Variation
- Authors/Creators
- Alexandra Cruz
- Contributors
- Shane Tobe (Supervisor) - Murdoch University, Centre for Biosecurity and One HealthCharlotte Oskam (Supervisor) - Murdoch University, Centre for Biosecurity and One HealthRachel Popelka-Filcoff (Supervisor) - The University of MelbourneAmy Roberts (Supervisor) - Flinders UniversityRobert Edwards (Supervisor) - Flinders University
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Publisher
- Murdoch University
- Identifiers
- 991005869305707891
- Murdoch Affiliation
- School of Medical, Molecular and Forensic Sciences
- Resource Type
- Doctoral Thesis
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