Abstract
Food spoilage organisms were isolated using standard procedures on Nutrient Agar, Cetrimide Agar and Pseudomonas Agar Base (supplemented with CFC). The samples were categorized as animal products (raw fish, egg, raw chicken, corned beef, pasteurized milk) and plant products (vegetable salad, water leaf ( Talinium triangulare ), boiled rice, tomatoes and pumpkin leaf ( Teifairia occidentalis ).They were characterised as Pseudomonas putida, Pseudomonas aeruginosa, Pseudomonas stutzeri, Burkholderia pseudomallei, Serratia rubidaea, Corynebacterium pilosum, Bacillus subtilis, Bacillus mycoides , Bacillus laterosporus, Bacillus laterosporus , Serratia marcescens, Bacillus cereus, Bacillus macerans, Alcaligenes faecalis and Alcaligenes eutrophus. Preliminary screening for biosurfactant production was done using red blood haemolysis test and confirmed by slide test, drop collapse and oil spreading assay. The biosurfactant produced was purified using acetone and the composition determined initially using Molisch’s test, thin layer chromatography and gas chromatography mass spectrometry. The components were found to be ethanol, amino acids, butoxyacetic acid, hexadecanoic acid, oleic acid, lauryl peroxide, octadecanoic acid and phthalic acid. The producing organisms grew readily on several hydrocarbons such as crude oil, diesel oil and aviation fuel when used as sole carbon sources. The purified biosurfactants produced were able to cause emulsification of kerosene (19.71-27.14%) as well as vegetable oil (16.91-28.12%) based on the emulsification index. This result suggests that the isolates can be an asset and further work can exploit their optimal potential in industries.
Highlights
Biosurfactants or microbial surfactants are surface metabolites produced by bacteria, yeast and fungi having very different chemical structures and properties (Ron & Rosenberg, 2001)
Scientists have commonly turned to contaminated sites as sources for the isolation of biosurfactant-producing and hydrocarbondegrading microorganisms which have produced varied results such as Peudomonas fluorescens from petroleum-contaminated soil (Barathi & Vasudevan, 2001), naphthalene degrading Bacillus pumilis strain isolated from oil sludge (Calvo, Toledo, & Gonzalez-Lopez, 2004), and Candida glabrata UCP 1002 obtained from petroleum hydrocarbons contaminated soil samples (Sarubbo, de Luna, & de Campos-Takaki, 2006)
Lee, and Hwang (2000) found that very often, the growth of microorganisms on hydrocarbons is accompanied by the emulsification of insoluble carbon sources in the culture medium and in most cases has been attributed to the production of emulsifying agents in the presence of these substrates
Summary
Biosurfactants or microbial surfactants are surface metabolites produced by bacteria, yeast and fungi having very different chemical structures and properties (Ron & Rosenberg, 2001). These biosurfactants are amphiphilic molecules of microbial origin whose hydrophobic and hydrophilic domains depend on the carbon sub-. They are potential alternatives of chemically synthesized surfactant in a variety of applications because of their advantages such as lower toxicity, higher biodegradability, better environmental compatibility, lower critical micelle concentration, ease of production, ability to be synthesized from renewable resources, higher foaming, higher selectivity, specific activity at extreme temperature, pH and salinity (Ilori, Amobi, & Odocha, 2005). The objective of this work is to isolate biosurfactantproducing bacteria from food waste as an alternative to environmental samples (water and soil) and to screen for emulsification ability
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