Antarctic soils may hold a distinctive microbial diversity. A large-scale genetic analysis, published in PNAS, found that 42 of the 46 Arthrobacter strains identified in the study’s Antarctic soil samples—about 91%—were not detected in samples from elsewhere in the world.
The researchers focused on Arthrobacter, a bacterial genus found widely in soils around the globe, rather than surveying all microbial life in Antarctica. The results suggest that the continent’s geographic isolation may have helped shape a local population of strains found nowhere else in the study’s comparisons.
Genomic analyses also indicated traits consistent with adaptation to Antarctica’s harsh conditions, but did not support every expected feature. In particular, the researchers found no evidence of exceptional resistance to extreme dryness, a major challenge in the continent’s dry valleys. The strains’ optimal growth temperatures were lower than the average for other bacteria worldwide, yet still higher than the temperatures they encounter in frozen soil.
The findings differ from earlier observations of marine bacteria associated with Antarctic invertebrates, some of which can grow at temperatures of up to 35°C in laboratory cultures. In the soil study, the striking result was the apparent geographic exclusivity of many Arthrobacter strains.
Further research will be needed to determine whether this degree of endemism is specific to Arthrobacter or is also found in other groups of Antarctic soil microbes.
Sources: Xataka.