Identification of enzyme-producing thermophilic bacilli isolated from marine vents of Aeolian Islands (Italy)

Abstract

Enzyme-producing thermophilic bacilli were isolated from different thermal sites located in and around Aeolian Islands (Italy) and characterised by both molecular and culture-based methods. Spore-forming bacteria with optimal growth from 45 to 70 °C were isolated from submarine vents and a geothermal well of Aeolian Islands (Italy). Eighteen selected strains were screened for extracellular enzyme presence by using nine substrates: Tween 20, Tween 80, tributyrin, soluble starch, xylan, dextran, carragenan, gelatine and casein. Sixteen isolates were able to grow at pH 9. The isolates were differentiated on the basis of restriction pattern of their amplified 16S rDNA (ARDRA) prior to 16S rRNA gene sequence analysis. On the basis of the most complete sequencing results strain V3 was identified as Geobacillus thermodenitrificans, most of isolates (10/14) was similar at high level (≥ 95%) to different reference strains of the species Bacillus licheniformis. The remaining isolates, exhibiting sequence similarity below 95%, may represent novel species of the genus Bacillus.