Conducting research on the medicinal properties of plants in the Biskra region, southern Algeria, is indeed a valuable and commendable endeavor. The rich biodiversity of Algerian vegetation provides an excellent opportunity to explore and understand the potential medicinal properties of various plants. Studying the antimicrobial activity of plant extracts is a common approach in microbiology and biochemistry. This method allows researchers to assess the ability of plant compounds to inhibit bacterial growth. For this purpose, we performed, using standard methods, the antimicrobial activity of extracts of six spontaneous plant species: Astragalus depressus L., Atractylis humilus L., Atractylis flava Desf.,Euphorbia guyoniana Boiss. & Reut., Euphorbia bupleuroides Desf. and Aloe vera (L.) Burm. F. against nine selected bacterial strains.The obtained results revealed that the different extracts of the studied plants gave different levels of antibacterial activity against all the microorganisms tested and that the n-butanol extract of Euphorbia bupleuroides at 2 mg showed the highest antibacterial activity with 27.66 mm in zone of inhibition against E. coli spp., followed by n-butanol extract of Astragalus depressus 5 mg with 21.00 mm inhibition zone against S.aureus ATCC25923 while the others showed moderate to low activities except for the two extracts A.humilus BuOH 5 mg and Aloe vera PE 2.5 mg that did not show any effectiveness. From these results we conclude that S. aureus ATCC25923 and S. aureus ATCC29213 are the most sensitive strains while E. coli ATCC25922 is the most resistant strain. However, all studied plant extracts are considered bacteriostatic compared to the MBC / MIC ratio values, which are ≥ 4. It appears from these results that plant extracts from certain studied plants have potential applications as natural alternatives for preservation or as antimicrobial substances. This is likely due to the presence of active substances in these extracts, which are notable for their specific chemical compositions.