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We isolated 100 morphologically-distinct halotolerant/halophilic yeasts from five estuarine sediments in Qua Iboe estuary, South-South Nigeria. A three-way analysis of variance (ANOVA) of the distribution was significant at p < 0.01; adjusted r2 = 0.851 suggesting that 85.1% of the variations in the number of halotolerant/halophilic yeast could be explained by the model. Sample, media and salt level main effects were all significant at p < 0.01, r2 = 0.732; 0.403 and 0.463 respectively. Only 17% of the yeasts demonstrated biosurfactant production potential by the oil displacement assay. Positive isolates were identified by macro/micro-morphological and physiological characterizations as species of Torulaspora, Pichia, Saccharomyces, Candida, Debaryomyces, Kluyveromyces, Schizosaccharomyces, Rhodotorula and Hortaea but the dominant halotolerant genus was Candida. Douglas creek sample harbored the highest number of halotolerant biosurfactant-producing yeasts probably by reason of its better proximity to Qua Iboe terminal where petroleum activity is high. Biosurfactants produced by all 17 yeasts could reduce surface tension to < 40 mN/m suggesting that halotolerant/halophilic yeasts in stressed environments secrete only effective surface-active compounds or not at all. Significant but moderate correlations existed between all correlate pairs involving oil displacement activity, surface tension, critical micelle concentration and emulsification activity of biosurfactants. The Pillai's Trace test of a one-way multivariate analysis of variance (MANOVA) involving surface tension reduction, oil displacement activity and emulsification activity was significant at F (48,102) = 3119.004, p < 0.005, partial ƞ2 = 0.999.Read Complete Article at ijSciences: V82019052065 AND DOI: http://dx.doi.org/10.18483/ijSci.2065 |
