New bacilli from shallow hydrothermal vents of Panarea Island (Italy) and their biotechnological potential

Abstract

Aims: To characterize bacilli isolated from shallow hydrothermal vents of Panarea Island (Italy) and evaluate their biotechnological potential.

Methods and results: Fifteen isolates were characterized by culture and molecular methods. Eleven isolates were thermophilic, six isolates were alkalophilic and four of them were haloalkalophilic. After 16S rRNA gene sequencing, four strains, exhibiting sequence similarity below 95% with deposited strains, may represent novel species of bacilli. One strain was strictly related to Geobacillus subterraneus, but shared phenotypic characteristics for which it could be considered a new strain of this species. Four strains were affiliated with different Bacillus spp. Most isolates produced gelatinase, lipases and amylase, and some were mercury tolerant. Exopolysaccharides (EPS) production was tested adding different sugars (glucose, sucrose, trehalose, fructose, ribose, xylose and mannose, 1% w/v) as a carbon source in a minimal medium. The highest EPS yield (185 mg l(-1)) was reached by strain 1A70 utilizing ribose as a carbon source.

Conclusions: Novel strains of Geobacillus and indigenous ribotypes of Bacillus with biotechnological potential inhabit shallow vents of Panarea Island.

Significance and impact of the study: New strains of thermophilic bacilli from Panarea are producers of useful biomolecules for industrial purposes as well as environmental and biotechnological applications.