Thermo-aerobic bacteria from geothermal springs in Saudi Arabia

Abstract

Biodiversity in geothermal springs in Saudi Arabia appears scanty and has not been thoroughly investigated. Geothermal springs are scattered in several areas in Saudi Arabia. Water samples were collected from ten hot springs and analyzed for different physical and chemical parameters. Fifteen isolates of thermo-aerobic bacteria were found. Bacillus cereus, B. licheniformis, B. thermoamylovorans, Pseudomonas sp., Pseudomonas aeruginosa and Enterobacter sp. were dominant in hot springs. Genetic relatedness indicated that eleven Bacillus spp. grouped together formed several clusters within one main group with high similarity. Plastic composite support tubes (PCS) were employed to stimulate the bacterial growth at high temperatures. The optimum temperature of isolates was 60°C. Thus, different blend of PCS were used to enhance the growth at higher temperatures. PCS blended with 20 and 15% (w/w) of dates pits and 5% (w/w) of yeast extract stimulated the growth of B. thermoamylovorans at 90°C.

Key words: Thermophilic bacteria, geothermal springs, genetic relatedness, extreme environments, 16S rDNA sequencing.