Bacterial community structures and ice recrystallization inhibition activity of bacteria isolated from the phyllosphere of the Antarctic vascular plant Deschampsia antarctica

Despite the recognized interest in Antarctic bacteria, the relationship between bacteria and Antarctic plants has scarcely been studied. Studies have demonstrated that bacteria in the phyllosphere may contribute to plant growth, but their role in native plants, such as Antarctic vascular plants living in hostile environments, is still unknown. Here we explore the bacterial community structure associated with the phyllosphere of Deschampsia antarctica, and evaluate the presence of ice recrystallization inhibition (IRI) activity in crude protein extracts from phyllosphere culturable bacteria. Denaturing gradient gel electrophoresis analysis (16S rRNA genes) showed significant differences in the total bacterial community of eight sampled plants; however, members of Pseudomonadales (Pseudomonas and Psychrobacter) and Rhizobiales (Agrobacterium and Aurantimonas) orders were dominant in all of the analyzed samples. Use of enterobacterial repetitive intergenic consensus polymerase chain reaction technique also revealed a high (>76 %) genetic diversity in 265 isolates from the phyllosphere. With respect to IRI activity, 32 isolates (21 %) showed IRI activity in crude protein extracts from cold-acclimated bacterial cultures, and 5 isolates (3 %) showed IRI activity in crude protein extracts from nonacclimated cultures.