Oral Presentation Australian Microbial Ecology 2019

Biogeography of actinobacteria in Australian and North Antarctica soils (#7)

Gupta Vadakattu 1 , Ricardo Araujo 2 , Andrew Bissett 3 , Frank Reith 4 , Chris Franco 2
  1. Agriculture and Food, CSIRO, Adelaide
  2. Medical Biotechnology, Flinders University, Adelaide, SA
  3. Oceans and Atmosphere, CSIRO, Hobart
  4. Land and Water, CSIRO, Glen Osmond, SA, Australia

Actinobacteria, Gram+ bacteria with DNA containing a high G+C percentage, represent one of the most abundant taxon identified in the soils across a diverse range of ecological regions worldwide. Actinobcteria area sought after due to their ability to produce a variety of bioactive metabolites and antibiotics, which has been extensively used to improve human and plant health. The abundance and distribution of soil actinobacteria is considered to be distinct from other microflora due to their size, ability to withstand extreme environments and dispersion abilities. Using the ‘Biomes of Australian Soil Environments’ (BASE) project generated database for bacterial (16S) diversity across environmental gradients at Australian continental scale, we developed a continental portrait of Australian Actinobacterial communities. A total of 20,931,120 high-quality reads were analysed and 197 different taxonomical groups (assigned at genus level) were classified as Actinobacteria. At the OTU level, 6,887 OTUs were found in the studied samples; 24 OTUs (0.003%) showed more than 100,000 reads each (frequent OTUs), while 4,624 OTUs (67%) showed less than 1,000 reads each (rare OTUs). The most common Actinobacteria families were Actinosynnemataceae, AK1AB1_02E, Frankiaceae, Gaiellaceae and Rubrobacteraceae. Extreme environments (cold - North Antarctica; warm – warm deserts) showed higher numbers of ‘endemic’ OTUs belonging to the taxa Euzebya, Nocardioides, Gaiella, Mycobacterium, Nocardioides, Pseudonocardia, Robrobacter and Streptomyces. The most pronounced effects on the composition of Actinobacteria at family and genus levels (either in presence or absence of Antarctica data) were associated with pH, climate (humidity and annual temperatures) and Ca availability. Additionally, at the OTU level, a second level of association was found for region, Koppen climate classification, land use, vegetation and soil classification. Although Land use effect was seen at regional and local level, the effects were not observed at continental scale. The high similarity between a group of OTUs found in Antarctica and King Island could be attributed to geogenic factors and the ability of Actinobacteria to persist in the soils for long periods.