Abstract

Sihem Ben Maachia*, Rafik Errakhi, Florence Mathieu, Mohamed Chérif and Ahmed Lebrihi

Two Bacillus sp. strains (B29 and B27) isolated from soil in the South of Tunisia were tested for their abilities to produce antimicrobial compounds. Both strains showed antimicrobial activity against Grampositive and Gram-negative bacteria, yeasts and fungi. The produced compounds were extracted by using four different solvents. The hexane extract allowed to obtain maximum of activity of the strain B29. The activity of the strain B27 was not elucidated by the four solvents used. Bio-autography results of B29 hexane extract revealed presence of different antibiotics and antifungal compounds with different Rf values of 0.3 and 0.76 for antifungal compounds and of 0.12, 0.14, 0.19 and 0.3 for antibiotics. Two active fractions were isolated from the culture broth of the strain B29 using semi-preparative HPLC. Partial sequencing of the 16S RDNA gene was used to identify both of Bacillus strains. They may be assigned to new Bacillus species.