Production of biosurfactants aspergillus niger and rhodotorula sp isolated from sugar cane bagasse dumpsite: A comparative study

Abstract

Biosurfactants are amphiphilic and surface-active compounds produced by microorganisms. Their relevance can be seen in petroleum, agriculture and pharmaceutics. Environmental pollution from agricultural wastes and by products has reached its peak and alternate applications of these wastes for other possible benefits are the current trends. This study compared the physicochemical properties and activity of biosurfactants produced from fungi isolated from sugar cane bagasse dumpsite. Two species of fungi were isolated and identified from sugar cane bagasse and identified as Aspergillus niger and Rhodotorula sp. by physiological and morphological tests. They were grown on mineral salt medium (MSM) for 14 days using sugar cane bagasse as carbon source. The microbial broths were assayed for biosurfactant production using drop collapse method, oil displacement method, and emulsification method. The emulsification activity of biosurfactants produced by Rhodotorula sp. recorded 51.133±4.964% which was significantly different when compared to that of Aspergillus niger (48.067±3.126%). The Aspergillus niger performed poorly in the drop collapse test assay (DCTA). There was a significant difference in the clear zone formation (CZF) produced by Rhodotorula sp (0.167±0.029 cm) when compared to that of the Aspergillus niger (0.133±0.289 cm). Biosurfactants produced were isolated using acid precipitate method and characterized primarily to yield high levels of carbohydrate and lipids. The biosurfactant produced by Rhodotorula sp. had a higher wetting and emulsification activity. This study suggests that the crude biosurfactants isolated from Rhodotorula sp shows promising possibilities for a wider application in pharmaceutical industries where emulsion is important towards efficiency in production.