Screening and Characterization of Bacillus Strains Producing Highly Thermostable Amylase from Various Hot Springs of Algeria

HIGHLIGHTS Screening extremophile Bacillus strains from various Hot Springs Characterization Of Bacillus Strains Producing Highly Thermostable Amylase Genetic identification of the best strains

Abstract Currently thermostable Amylase represents a broad biotechnological interest and desired by a various industries. In this study, forty-six bacterial strains belonging to the genus Bacillus were isolated from various hot springs in the North West of Algeria based on their ability to degrade starch and produce amylase in Starch Agar medium. The majority of isolates showed a positive amylolytic activity. In order to select the most thermostables amylase the effect of temperature on enzymes was estimated, therefore the study of amylase thermostability was culminated by the selection of Four Strains having an interesting optimum of activity and range of stability, reaching 75 °C for the strains HBH1-2, HBH1-3, HBH3-1and 85 °C for the strain HC-2, This indicates that the Enzyme produced by retained strains have optimum activity at high temperature. The identity of the selected strains was established on the basis of the morphological, biochemical characteristics and phylogenetic position as determined by 16S Ribosomal DNA gene sequencing. The whole strains belonged to the genus Bacillus and their phylogeny were also reported in this study.

Characterization of a hyperthermophilic sulphur-oxidizing biofilm produced by archaea isolated from a hot spring

Background: Sulphur-oxidizing microorganisms are widely used in the biofiltration of total reduced sulphur compounds (odorous and neurotoxic) produced by industries such as the cellulose and petrochemical industries, which include high-temperature process steps. Some hyperthermophilic microorganisms have the capability to oxidize these compounds at high temperatures (N60°C), and archaea of this group, for example, Sulfolobus metallicus, are commonly used in biofiltration technology. Results: In this study, a hyperthermophilic sulphur-oxidizing strain of archaea was isolated from a hot spring (Chillán, Chile) and designated as M1. It was identified as archaea of the genus Sulfolobus (99% homology with S. solfataricus 16S rDNA). Biofilms of this culture grown on polyethylene rings showed an elemental sulphur oxidation rate of 95.15 ± 15.39 mg S l-1 d-1, higher than the rate exhibited by the biofilm of the sulphur-oxidizing archaea S. metallicus (56.8 ± 10.91 mg l-1 d-1). Conclusions: The results suggest that the culture M1 is useful for the biofiltration of total reduced sulphur gases at high temperatures and for other biotechnological applications.

Thermophilic bacteria in Moroccan hot springs, salt marshes and desert soils

The diversity of thermophilic bacteria was investigated in four hot springs, three salt marshes and 12 desert sites in Morocco. Two hundred and forty (240) thermophilic bacteria were recovered, identified and characterized. All isolates were Gram positive, rod-shaped, spore forming and halotolerant. Based on BOXA1R-PCR and 16S rRNA gene sequencing, the recovered isolates were dominated by the genus Bacillus (97.5%) represented by B. licheniformis (119), B. aerius (44), B. sonorensis (33), B. subtilis (subsp. spizizenii (2) and subsp. inaquosurum (6)), B. amyloliquefaciens (subsp. amyloliquefaciens (4) and subsp. plantarum (4)), B. tequilensis (3), B. pumilus (3) and Bacillus sp. (19). Only six isolates (2.5%) belonged to the genus Aeribacillus represented by A. pallidus (4) and Aeribacillus sp. (2). In this study, B. aerius and B. tequilensis are described for the first time as thermophilic bacteria. Moreover, 71.25%, 50.41% and 5.41% of total strains exhibited high amylolytic, proteolytic or cellulolytic activity respectively.