PRODUCTION OF BIOSURFACTANT BY ACTINOMYCETES ISOLATED FROM PLASTIC-ENRICHED COMPOSTING SOIL

Abstract

This study examined the production of biosurfactant by plastic-enriched composting- soil actinomycetes. Starch casein medium was used for the isolation of the actinomycetes. The plastic-enriched composting soil samples were obtained from Edo State Waste Management Dumpsite located at Iyowa Community in Benin City, Edo State, Nigeria. From the physico-chemical parameters analysed, it was revealed that the presence of plastic compost in the soil resulted in increase in the mean value of chloride content (12.81± 0.33 mg/kg). The total hydrocarbon and carbon contents were 2.60±0.04 and 2.09±0.3 (mg/kg) respectively and were appreciably high owing to plastic debris and organic waste deposited in the site. The biosurfactant producing organism isolated in the study was confirmed to be Streptomyces sp. based on morphological and biochemical tests. The isolate was screened for their ability to produce biosurfactant. The biosurfactant produced was screened for its emulsification activity and surface tension reduction ability by subjecting them to varied temperatures, pH and salt contents. The biosurfactant was found to have a better surface tension of 101.00±0.00 dynes/cm at a lower temperature than at a higher temperature but was reverse for the emulsification activity as it was better at a higher temperature of 121oC (36.33±0.67) than a lower temperature. Furthermore, surface tension and emulsification activity were better at an alkaline pH of 10(118.00± 1.00) and (34.33± 0.33) respectively. There were little effects of salt concentration on biosurfactants surface tension and emulsification activity. The biosurfactant produced from Streptomyces sp was confirmed at be a glycolipid.