Similarity in growth response of Aspergillus terreus isolates under mimic hydrothermal vent conditions suggests no physiological growth barrier between terrestrial and marine environments

Abstract

This study investigated the phylogeny of 17 isolates of Aspergillus terreus, cultured from soil, macroalgae, hydrothermal vent sediment in terrestrial and marine environments, and their growth response under combined effect of sea salt concentration (0 g l-1 or 30 g l-1), temperature (25 degrees C or 45 degrees C), pH (3 or 7). The isolates did not form clades corresponding to their ecological origin based on a combined phylogenetic analysis of five DNA regions (internal transcribed spacers of ribosomal DNA, calmodulin, beta-tubulin, elongation factor 1-alpha, RNA-polymerase second large subunit). All isolates were able to grow under all tested conditions, including 45 degrees C/pH 3, environmental conditions possible at a hydrothermal vent site. The growth rate of the isolates was generally higher at 25 degrees C than at 45 degrees C and at pH 7 than at pH 3, and was similar at 0 g l-1 and 30 g l-1 sea salt concentrations. These results collectively suggest that the ocean is a sink of both marine and terrestrial isolates of A. terreus, which has the physiological and genetic capacities to grow in both environments.