SCREENING AND COMPARATIVE ANALYSIS OF BIOSURFACTANT-PRODUCING BACTERIA ISOLATED FROM VARIABLY CONTAMINATED SITES OF KARACHI COAST
Keywords:
Biosurfactant, Screening, Characterization, ContaminationAbstract
Screening and comparison of biosurfactant-producing bacteria isolated from variably contaminated sampling sites of Arabian Sea coast of Karachi was conducted. Sampling sites were divided into three categories based on contamination: “highly contaminated (HC)”, “moderately contaminated (MC)” and “undisturbed/ uncontaminated (UC)”. Isolates were screened through a combination of seven screening tests. All the tests were conducted using three hydrocarbons crude oil, xylene, and hexane. For hemolytic activity maximum number (36%) of isolates from MC showed best activity. The oil spreading method revealed the highest occurrence (40%) of all the isolates from UC area. BATH assay, Emulsification Index and Emulsification assay revealed positive adherence and emulsification with at least one of the hydrocarbons tested in more than 95% of the isolates irrespective of sampling areas. Best adherence potential was observed with hexane in maximum number of isolates. Emulsification Index was best in isolates with crude oil and in Emulsification assay best results were observed with xylene. For CTAB agar plate assay and drop-collapse method highest percentages of isolates (60% and 96% respectively) from HC area showed positive results. These results indicate potential of biosurfactant production in isolates, but performance was variable with respect to different screening tests and hydrocarbons tested.
The significance of the study is to isolate biosurfactant producing bacteria from contaminated sites of Karachi. Biosurfactants are naturally occurring amphiphilic molecules present in the environment. They are efficiently used in various industries like food processing, pharmaceutical, healthcare, agricultural and in bioremediation of polluted environment. The isolation of microbes from marine water is supposed to be a good producer. Biosurfactant have advantages of low toxicity, easy biodegradability, high foaming, and can perform under extreme conditions. These molecules can reduce surface and interfacial tension in aqueous and hydrophobic phases. As compared to chemical synthesized surfactants, microbial produced surfactants are miscellaneous and structurally diverse in nature. These distinctive properties of biosurfactant make them a potential user for industries and the best alternative of synthetic surfactant.
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Copyright (c) 2026 Faiza A. Ansari, Bashir Ahmed, Erum Shoeb, Jameela Akhtar, Khaizran Siddiqui, Ariba Naz, Uzma Badar (Author)
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