Isolation and Characteristics of Biotechnologically Important Antagonistic Thermophilic Bacteria from Rhizosphere of Haloxylon salicornicum

Rhizobacteria are an active part of microbial population in the rhizosphere of plants. In this study, twenty rhizobacteria were isolated from the rhizosphere of a perennial grass, Haloxylon salicornicum, found in Cholistan desert, an arid landmass near Bahawalpur Pakistan, in one set of experimental conditions. Colony characteristics, biochemical and molecular analyses of these isolates were performed. All isolates were bacilli, gram positive with off-white colonies and exhibited typical bacilli colony morphology. None of the isolates was gelatinase, urease, indole, H2S and catalase producer. Eleven isolates were amylase producers and 8 isolates were acid producers. All isolates fermented glucose, 3 fermented lactose and 19 fermented fructose. Molecular data revealed that out of twenty isolates, 14 isolates showed 91-99% identity with Brevibacillus borstelensis, 4 with Bacillus subtilis (97-98%) and 2 with Bacillus licheniformis (94-99%) through BLAST analysis. All identified bacterial isolates cladded with their respective groups in the phylogenetic tree. Many (11-15 out of 20) of the isolates were more effective in inhibiting growth of the tested bacterial strains as compared to the positive control (Ampicillin 50 μg/disc). We conclude that bacilli are the predominant form populating rhizosphere of this desert grass. Among the isolated bacteria Brevibacillus borstelensis, Bacillus subtilis and Bacillus licheniformis are the most predominant species.