Resumo

Introduction and Objectives: Spores of Bacillus atrophaeus ATCC 9372 are attractive microorganism for pharmaceutical and biotechnological areas due wide application and facility to obtain molecules’ production for industrial interests. Biosurfactants, which are included in these bioproducts have antimicrobial, antiadhesive, antitumoral activities and high added value. The objective of this work was to evaluate the production of biosurfactants which are displayed into the extracellular medium by B. atrophaeus spores in order to improve their production. Material and Methods: Aliquotes of 1 mL of Bacillus atrophaeus ATCC 9372 (initial concentration from 10² up to 10⁶ spores/mL) were inoculated in 50 mL and 100 mL of TSB (Tryptic Soy Broth) in 250 mL erlermeyers which were covered with a lid and gauze, separately, and displayed on shaker (T-420 model, Tecnal) at 37ºC and 150 rpm for 24 hours. The supernatant and pellet were separated by centrifugation (5804 model, Eppendorf) at 4ºC and 5000 rpm for 30 minutes. The expression of biosurfactants was measured into supernatant, for each inoculum concentration, in triplicate, using tensiometer (K9 model, Krüss) and distilled water as standard solution (superficial tension ( γ ) = 75.5 mN/m). Results and Conclusion: Using 50 mL of TSB in erlemeyers covered with gauze, the superficial tension of 51.9 mN/m was obtained in an initial concentration of 10⁶ spores/mL and 52.9 mN/m in an initial concentration of 10² spores/mL (average pH of 6.9 and 7.3 for pellet and supernatant, respectively). Bacillus atrophaues inoculated in 50 mL of TSB in 250 mL erlenmeyer covered with lid has showed the same fashion with a γ = 51.7 mN/m in an initial concentration 10⁴ spores/mL and γ = 50.7 mN/m in an initial concentration 10² spores/mL. The pH of this experiment was 7.5 (pellet) and 6.9 (supernatant). When Bacillus atrophaeus was inoculated in 100 mL of TSB with gauze, it was showed that the tension was higher than 50 mL experiments, reaching γ = 61.3 mN/m (inoculum concentration 10⁶ spores/mL). The procedure using an initial concentration of Bacillus atrophaeus 10² spores/mL with 50 mL of TSB in 250 mL erlenmeyers covered with gauze was performed from 1 up to 6 days, showing a mean superficial tension of 50.8 mN/m. In this study, all data has shown that the expression of biosurfactants was independable of initial microorganism population.