NITROGEN OPTIMIZATION ON RHAMNOLIPID BIOSURFACTANT PRODUCTION FROM Pseudoxanthomonas sp. G3 AND PRESERVING TECHNIQUES

• Main Author: Ghina Utami, Salsabila
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/42436
• Institution: Institut Teknologi Bandung

Biosurfactant is a compound of metabolizing microorganisms, functioning to reduce surface tension, act as an emulsifier, dispersant, anti-adhesive, and others. As a result of these capabilities, biosurfactants are used in various industries, increasing demand for it every year. Optimization of biosurfactant production needs to be done to increase production quantity, but reduce prouduction cost. This study aims to determine the type of nitrogen source and the most optimal concentration for biosurfactant production by Pseudoxanthomonas sp. G3. and determine the most effective biosurfactant preservation method. The method used in this research is biosurfactant production by Pseudoxanthomonas sp.G3 using minimal salt medium with an addition of 2% light crude oil as a carbon source and 3 kinds of nitrogen sources in the form of urea, sodium nitrate, and ammonium nitrate. The activity of biosurfactants from each nitrogen source were measured by emulsification index (E24), interfacial tense (IFT), oil drop assay, and biosurfactant dry weight. Biosurfactant production is carried out and then preserved using 3 different treatments, (a) Without the addition of preservatives, (b) Addition of potassium sorbate 0.2% (w/v) as preservative, and (c) Stored in powder form. Each were stored at room temperature. However, treatments a and b were also stored at 4oC. The results of this study show that biosurfactant production using sodium nitrate as a nitrogen source provides the highest activity and yield values. The E24 value was 76.63%, the clear zone diameter was 0.875 cm, the decrease in IFT was 35.4%, and the biosurfactant dry weight was 0.45 g/L. Growth curve and production curve were made with 3 concentrations of sodium nitrate (0.3%; 0.6%; 1.2% (w/v)). It was found that maximum cell growth occurred at 24 hours incubation while maximum biosurfactant production occurred at 72 hours incubation. Based on the results of the production curve, the optimum sodium nitrate concentration is 0.3% (w/v). Microbial contamination occurred at week 3 of storage, with treatment without the addition of preservatives and stored at room temperature having the highest number of contamination. During storage, the activity of biosurfactants (emulsification and IFT) decrease. The conclusion of this study is the most optimal nitrogen source for biosurfactant production by Pseudoxanthomonas sp. G3 is sodium nitrate 0.3% (w/v), and the most effective biosurfactant preservation method is by adding potassium sorbate stored at 4oC.