Abstract
Although there is great interest in cultivable Antarctic microorganisms for potential biotechnology applications, little is known about the microbial diversity and the metabolic potential of samples from Antarctic environments. Two hundred and fifty bacterial isolates were obtained from Antarctic soil and from rhizosphere samples of the Antarctic plants Colobanthus quitensis and Deschampsia antarctica. The samples were screened using amplified ribosomal DNA restriction analysis (ARDRA) and identified by 16S rRNA sequencing. Their metabolic potential was predicted in silico using the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUS) tool. Additionally, the strains were screened for the production of amylases, proteases, cellulases and chitinases at 4, 12 and 25 A degrees C. The bacterial isolates obtained were classified into the phyla Proteobacteria, Arthrobacter, Firmicutes and Bacteroidetes. The species belonging to the genus Pseudomonas were predominant in all the soil and rhizosphere samples. Twenty-one different Operational Taxonomic Units (OTUs) were detected, and the functional profile of each OTU indicated that most of the predicted genes were related to metabolic functions. Among the OTUs, one affiliated with the genus Rhodococcus sp. (OTU 7) and one affiliated with the genus Rhizobium sp. (OTU 18) showed the largest numbers of predicted genes for amino acid and carbohydrate metabolism and for xenobiotics. The traditional enzyme screening indicated that only proteases were produced by all the bacterial isolates and that the bacterial isolates with greatest predicted metabolic potential (OTUs 7 and 18) also presented the greatest diversity of enzyme production. The results suggested that gene prediction might reflect, at some level, the real metabolic plasticity of the microorganisms and provide a tool for screening promising biotechnological strains, including strains producing multiple enzymes.