This study investigates the bacterial communities in Antarctic soils across the continent and sub-Antarctic islands, aiming to assess whether bacterial diversity and distribution align with the current Antarctic Conservation Biogeographic Regions (ACBRs). The researchers used 16S rRNA gene amplicon datasets to analyze bacterial phylogenetic patterns and environmental drivers. Key findings include: 1. **Bacterial Diversity and Community Composition**: Soil bacterial diversity and community composition did not fully conform to the ACBR classification. Only 19% of the variability was explained by the ACBR classification, with significant differences observed between continental and maritime Antarctic regions. Bacterial communities showed partial overlap within these regions but did not fully reflect the division into separate ACBRs. 2. **Bioclimatic Influence**: Bacterial communities were partially shaped by bioclimatic conditions, with 28% of dominant genera showing habitat preferences linked to at least one of the bioclimatic variables. These genera were also identified as indicator taxa for the ACBRs. 3. **Regional Clustering**: Samples from different ACBRs showed significant clustering, with the highest clustering observed between samples from the continental and maritime Antarctic regions. The North Victoria Land (ACBR8) samples showed the highest microbial compositional differences compared to other ACBRs, possibly due to higher temperatures and precipitation rates. 4. **Unexplained Variance**: A high percentage of unexplained variance was observed when considering both ACBR classification and bioclimatic variables. This suggests that microbial communities are influenced by multiple environmental factors and dynamics, including geographical distance, soil histories, and climate legacies. 5. **Conclusion**: The current ACBR subdivision of the Antarctic continent does not fully reflect bacterial distribution and diversity. The study provides a comprehensive baseline for biodiversity conservation efforts and highlights the need for more extensive campaigns to systematically sample and characterize Antarctic and sub-Antarctic soil microbial communities. Keywords: Antarctic Conservation Biogeographic Regions (ACBRs), Antarctic soil microbiome, Biogeography, Microbial diversity, Regionalization, Soils, Bioclimatic variablesThis study investigates the bacterial communities in Antarctic soils across the continent and sub-Antarctic islands, aiming to assess whether bacterial diversity and distribution align with the current Antarctic Conservation Biogeographic Regions (ACBRs). The researchers used 16S rRNA gene amplicon datasets to analyze bacterial phylogenetic patterns and environmental drivers. Key findings include: 1. **Bacterial Diversity and Community Composition**: Soil bacterial diversity and community composition did not fully conform to the ACBR classification. Only 19% of the variability was explained by the ACBR classification, with significant differences observed between continental and maritime Antarctic regions. Bacterial communities showed partial overlap within these regions but did not fully reflect the division into separate ACBRs. 2. **Bioclimatic Influence**: Bacterial communities were partially shaped by bioclimatic conditions, with 28% of dominant genera showing habitat preferences linked to at least one of the bioclimatic variables. These genera were also identified as indicator taxa for the ACBRs. 3. **Regional Clustering**: Samples from different ACBRs showed significant clustering, with the highest clustering observed between samples from the continental and maritime Antarctic regions. The North Victoria Land (ACBR8) samples showed the highest microbial compositional differences compared to other ACBRs, possibly due to higher temperatures and precipitation rates. 4. **Unexplained Variance**: A high percentage of unexplained variance was observed when considering both ACBR classification and bioclimatic variables. This suggests that microbial communities are influenced by multiple environmental factors and dynamics, including geographical distance, soil histories, and climate legacies. 5. **Conclusion**: The current ACBR subdivision of the Antarctic continent does not fully reflect bacterial distribution and diversity. The study provides a comprehensive baseline for biodiversity conservation efforts and highlights the need for more extensive campaigns to systematically sample and characterize Antarctic and sub-Antarctic soil microbial communities. Keywords: Antarctic Conservation Biogeographic Regions (ACBRs), Antarctic soil microbiome, Biogeography, Microbial diversity, Regionalization, Soils, Bioclimatic variables