Biosurfactants are one of the microbial bioproducts that are naturally synthesized and are applicable for many industrial purposes. In this study, antibacterial, stability and antibiotic susceptibility of biosurfactant was evaluated. Biosurfactants produced from different substrates (groundnut cake, cassava flour waste, pome, cooking oil, engine oil, cassava waste water, molasses, cassava peel, potato) by Pseudomonas taenensis were evaluated for antibacterial activity using agar well diffusion method. Antibiotics susceptibility of Pseudomonas taenensis was carried out using different antibiotics (augmentin, ofloxacin, tetracyclin and ciprofloxacin, cotrimoxazole, pefloxacin, amoxylin, ceftriazone, nitrofuranton and gentamycin). The stability of the biosurfactant was evaluated by adjusting the biosurfactant to: pH (2, 4, 6, 8, 10 and 12) using 1M NaOH and 1M HCl, temperature (4, 30, 37, 55, 75 and 100 °C) and NaCl (0, 5, 10, 15, 20 and 25 %). Results showed that only biosurfactant produced using cassava waste water as substrate was sensitive to Escherichia coli while biosurfactant produced using cassava flour waste, pome and molasses were sensitive to Staphylococcus aureus. Biosurfactant-producing isolate (Pseudomonas taenensis) was sensitive to four antibiotics (augmentin, ofloxacin, tetracyclin and ciprofloxacin) and resistant to six antibiotics (cotrimoxazole, pefloxacin, amoxylin, ceftriazone, nitrofuranton and gentamycin). Biosurfactant was stable over all the wide ranges of pH, temperature and sodium chloride concentrations investigated. This study therefore revealed that biosurfactant have good stability, thus, could survive environmental stress; Not all biosurfactant and biosurfactant producers have antimicrobial and antibiotic property.