Publisher: Bachudo Science Co. Ltd

isolation of Biosurfactant/Bioemulsifier-Producing Bacteria From Soil and Sewage Sludge

S. K. C. Obi, B. N. Okolo, C. U. Anyanwu
KEYWORDS: Bioemulsifier, biosurfactant; emulsification emulsion; surface tension.


Biosurfactant-producing bacteria were isolated from sewage sludge and petroleum contaminated and uncontaminated soils. Isolates were screened for biosurfactantlbioemulsifier production in mineral salts medium with different carbon sources (glucose, sucrose, n-paraffin and kerosene) using the Du-Nouy ring technique. Nine positive isolates were obtained, namely, one Arthrobacter sp., three Bacillus spp., three Pseudomonas spp. and two Serratia spp Glucose and sucrose, as sole carbon source, produced the highest number of positive results but sucrose gave the lowest surface tension value of 39.8 dynes/cm and the most stable emulsion after 24 h with culture supernatant of a Serratia sp. Six of the isolates reduced the surface tension of the fermentation broth to less than 45 dynes/cm with sucrose and glucose as carbon source. Kerosene was the least supportive carbon source for biosurfactant production. All the nine isolates produced emulsion witn paraffin oil and olive oil while the least emulsification index (El24) obtained was with kerosene as carbon source.

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