Prosophis juliflora (Sw.) DC. commonly known as “mesquite” is a native tree of tropical America
and is naturalized in many countries including Egypt and India. In the present study, the antimicrobial activities
of acetone, chloroform, diethyl ether, methanol, ethanol and DMSO extract of P. juliflora was studies. The extracts
and the tetracycline as control were tested in vitro against 6 bacterial species and 4 fungal species by well
diffusion method. Escherichia coli, Bacillus subtilis, Serratia marcescens, Klebsiella pneumoniae, Staphylococcus
aureus, Pseudomonas fluorescens, Phomopsis leptostromiformis var. occidentalis, Pestalotia foedans, Fusarium
oxysporum and Paeciliomyces variotii were used in this investigation. The results indicated that DMSO extract
exhibited the better antibacterial activity against Escherichia coli (21mm), Serratia marcescen (16 mm),
Staphylococcus aureus (17.9mm), Pseudomonas fluorescens (16.5 mm), Paeciliomyces variotii (13.2 mm) and
Phomopsis leptostromiformis (11mm). The methanol extract exhibited the better activity against Bacillus
subtilis(23 mm) and Pestalotia foedans (16 mm). The Ethanol extract showed better activity against Klebsiella
pneumoniae (11 mm) and interesting found that no extract showed activity against the fungi Fusarium oxysporum.
