Isolation And Characterization Of Biosurfactants Produced From The Methanol Pulp Extract Of Spondias Mombin.

Abstract

Pseudomonas aeruginosa was grown to produce biosurfactants using a batch cultivation system in which the media components were not replenished during fermentation. Four different culture media were used. Medium I contained basal mineral medium (BMM) and Spondias mombin (SM) as carbon source. Medium II consisted of basal mineral medium (BMM) and equal ratio of Spondias mombin and glucose (SM+GLC) as carbon substrate. Medium III consisted of basal mineral medium (BMM) and glucose (GLC) only as carbon source while Medium IV was composed of only nutrient broth (NB) and served as the control medium. Tween 80 was used as standard surfactant. The quantitative and qualitative phytochemical screening of Spondias mombin extract showed the presence of alkaloids (0.07mg/g), flavonoids (0.16mg/g), steroids (0.16mg/g), carbohydrate (5.30%), protein (1.40%), fats (2.54%), fibre (0.67%), ash (1.59%) and moisture (88.48%). The results of Pseudomonas aeruginosa growth estimation in culture broth between day one and twelve showed that the four culture media encouraged growth of Pseudomonas aeruginosa at different rates. The culture broth supernatants were then screened for biosurfactant activity after a period of twelve days. The results of haemolytic activity in all the four culture media showed that clear zones of haemolysis on blood agar for medium I, II, III, and IV were 3.4cm, 2.6 cm, 1.5 cm and 1.1 cm respectively. The oil drop collapse test occurred in 30 seconds in medium I and between 1 to 3 minutes in other media. The oil spreading/displacement ctivity revealed that medium I had average clear zone of diameter 3.8 cm, medium II (2.7cm), medium III (1.6 cm) and medium IV (0.7cm). The emulsification activity of Cwas greater than 50% in media I and II, but less than 50% in media III and IV. The results of temperature stability of the biosurfactants in the four culture broth supernatants after incubation was stable across a temperature range of 30 to 900C. The pH stability of the biosurfactants across a range of pH 2 to 6 revealed that the emulsification index was reduced between pH 2 to 6 indicating that the stability of biosurfactants was affected in acidic medium. The results of the biosurfactant yields showed that 4.8 g/L, 3.8 g/L, 2.6 g/L and 1.7 g/L were produced for medium I, II, III and IV respectively. The yields of the biosurfactants in the various media showed that medium I performed best. The results of the biochemical characterization of biosurfactants showed that carbohydrate concentrations in the various media were: medium I (0.6 g/L), medium II (0.46 g/L), medium III (0.35 g/L) and medium IV (0.06 g/L). The quantitative lipid analysis of biosurfactants isolated from each of the culture medium was found to be 0.44 g/L (medium I), medium II (0.3 g/L), medium III (0.13 g/L) and medium IV (0.01 g/L).The result of the characterization of the biosurfactants for protein determination revealed that no protein was detected in each of the culture media indicating that the biosurfactants produced were of glycolipid-type