Informatics Publishing Limited

Abstract

Corrosion is a leading cause of pipelines failure in the oil and gas industries because of the activities of microbial populations.  The aim of the study was to assess microbial diversity associated with corrosive biofilms of oil pipelines in two sites (Warri in Delta and Oshie in Rivers States) within the Niger Delta region of Nigeria. Coupons were inserted into the inner surfaces of the pipelines (9’’, 10’’, 18’’ and 24’’ diameter) through the access valves for a period of 127 days. The coupons were detached from the inner surfaces of the pipelines at the end of 127 days and biofilms formed on the surfaces of each coupon were scraped with sterile razor blades and collected into sterile bottles containing 5 ml phosphate-buffered saline at pH 7 and taken to the laboratory for the cultivation fungi. The results from Rivers State (site 1) showed the following fungal species: Verticillium dahlae, Botrytis cineriae, Penicillium nalgiovese Humicola. grisae, Monilia balanitis,, Saccharomyces cerevisae, Aspergillus fumigates,. semitectum, Helminthosporium maydis and Eurotium repens. In Delta State (site 2) the fungal species detected were: Verticillium dahlae, Botrytis cinerae, Penicillium corylophilum Humicola grisae, Monilia balanitis,r, Saccharomyces ccerevisiae,Fusrium oxysporum,  Aureobasidium pullulans, Aspergillus fumigatus and Hormoconis resinae. The results revealed a Sorenson’s coefficient (cc) of 0.60, indicating that fungal communities in site 1 and 2 have a bit of overlap or similarity. The results further showed that diversity and evenness in site 2 are much higher than in site 1. Fungal populations in sites 2 are not only higher in the number of species present, but the individuals in the community are distributed equitably among these species.  This shows that pipelines located in site 2 (Delta State) are likely to be severely corroded than site 1 (River State). Microbial communities in biofilms developed on surfaces of metals in natural environments are heterogeneous and there is significant uncertainty concerning how many of these organisms contribute to corrosion of metals. Therefore, the thorough knowledge of microbial species inhabiting biofilms of oil pipelines will give effective means of detecting, monitoring and control of corrosion of oil pipelines; this will significantly reduce pollution of agricultural lands and the environment by oil spillages in the Niger Delta.

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