Effect of Cultural Conditions on Biosurfactant Production by Candida sp. Isolated from the Sap of Elaeis guineensis
I. V. Nwaguma *
World Bank Africa Centre of Excellence, Centre for Oilfield Chemicals Research, University of Port Harcourt, East-West Road, Choba, River State, Nigeria.
C. B. Chikere
Department of Microbiology, Faculty of Science, University of Port Harcourt, East-West Road, Choba, River State, Nigeria.
G. C. Okpokwasili
Department of Microbiology, Faculty of Science, University of Port Harcourt, East-West Road, Choba, River State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Aims: This study is aimed at determining the effect of cultural condition on biosurfactant production by Candida sp. isolates from saps of Elaeis guineensis.
Methodology: Chemical analysis of the sap was carried out. Yeast isolates from the sap were screened for biosurfactant production based on emulsification index (E24), emulsification assay, haemolytic assay, oil displacement test, CTAB and tilted glass slide ability. The best biosurfactant-producing yeast isolate was identified based on its phenotypic, microscopic, and biochemical characteristics. The emulsification capacity of the produced biosurfactant on selected oils was studied. Optimum cultural and nutritional requirements (temperature, pH, inoculum concentration, nitrogen sources and carbon sources) for biosurfactant production by the isolate were determined.
Results: The characteristics of the sap from Elaeis guineensis were reducing sugar (0.51 ± 0.03 mg/ml), alcohol (14.04 ± 0.15%), specific gravity (0.827±0.024), and pH (5.68±0.03). The crude biosurfactant produced displaced a thin film of crude oil on petri dish by 55 mm, and revealed high emulsification index (E24) of 52.5% using Olive oil as substrate compared to E24 of 60.6% by sodium dodecyl sulphate (SDS). Based on colonial, microscopic, and biochemical characteristics, the isolate SA2 was identified as Candida sp. The crude biosurfactant showed varying capacity in emulsifying the different oils that were examined. Optimization data revealed maximum biosurfactant production after 7 days of incubation, inoculum concentration of 10%, at temperature of 20ºC, pH of 2 with cassava peel as substrate.
Conclusion: The study has demonstrated the capacity of Candida sp. from the sap of Elaeis guineensis to produce biosurfactant utilizing cassava peel as substrate. The use of cassava peel, which represents a low-cost substrate, is important in reducing the cost of biosurfactant production. Moreover, using yeasts from Elaeis guineensis make the production process ecologically friendly.
Keywords: Biosurfactant, Candida sp, optimization, Elaeis guineensis