Screening for some Bacillus spp. inhabiting Egyptian soil for the biosynthesis of biologically active metabolites

Author: N. M. Morsi ¹, N. M. Atef ^1* and H. El-Hendawy ²

Received 27 January 2010, accepted 11 April 2010.

Abstract

In this study, a number of Bacillus strains were isolated from soil collected from different areas of the experimental fields belonging to the faculty of Agriculture, Cairo University. The isolates which showed antimicrobial effects were identified as Bacillus licheniformis, B subtilis, B. sphaericus, B. circulans (3 isolates), B. badius, B. azotoformans, Brevibacillus brevis (2 isolates), and an unidentified isolate. The activity of crude filtrate, obtained from the aerobically grown isolates, using four different media, was evaluated in vitro against indicator microorganisms including phytopathogenic bacteria and fungi as well as food spoiling bacteria namely Xanthomonas campestris, Pseudomonas marginalis, Erwinia carotovora, E. chrysanthemi, Fusarium moniliforme, F. equiseti, Staphylococcus aureus and Escherichia coli. The antimicrobial activity of each of the Bacillus isolates differed greatly towards the indicator organisms regarding the medium used for growth. This activity was potent when the isolates were grown in nutrient broth, while nearly no activity was detected when molasses-yeast extract medium was used. Phytopathogenic bacteria were the most susceptible microorganisms compared to phytopathogenic fungi and food-spoiling bacteria. Some of the antimicrobial compounds produced by Bacillus spp. were identified by using GC-MS analysis. These compounds may be dibutyl phthalate, phenyl acetic acid, phthalic acid and kasugamycin, production of these compounds were by the bacterial isolates B₂, B₃, B₁₆ and B₆,respectively.

Key words: Bacillus spp., phytopathogenic microorganisms, biologically active compounds.