ABSTRACT

Metal corrosion is an electrochemical reaction between the environment and a metal, in which microbes are thought to play a very important role. These microorganisms do not only cause corrosion, but they can also inhibit or protect against corrosion. Fungi are the most dessicant – resistant microorganisms and are ubiquitous in atmospheric environments. About five fungal organisms were isolated using Starkey media from the soil of corroded pipeline tank. The influence of these fungal isolates on both rusted and non – rusted mild steel plates were studied for a period of 25 days. Among the five fungal isolates, Non – rusted Isolate (NR) – 1 and Rusted Isolate (R) – 3 showed minimum corrosion reaction on mild steel plates, based on the results of weight loss and dissolved iron content. The results revealed that the two isolates showed minimum rate of corrosion on mild steel plates due to the passive mechanism of microbes upon the plates. Therefore the above isolates (NR -1 and R- 3) was identified using molecular markers and it was found to be Aspergillus flavus and Alternaria alternata respectively.

INTRODUCTION

Corrosion is a major problem worldwide that affects a large variety of industries such as oil, refinery, shipping and nuclear power generation. It also occurs in many other industries such as water treatment, chemical processing and upkeep of historical monuments. 1 The word ”corrode” is derived from corrodere, which means ”to gnaw to pieces”. Thus corrosion can be defined as a chemical or electrochemical reaction between a material, usually a metal and its environment that deteriorate the material and its properties. 2, 3

Thus environment plays a dual role in corrosion of materials. Environment that cause corrosion are called corrosive and the materials/ metals that suffer from corrosion are called corrodible. 4 The primary factors to describe the environment are as follows: (a) Physical factors: temperature, availability of water (b) chemical composition, constituents and concentrations (c) Biological factors: Microbes. 5 Corrosion exhibit both direct and indirect effect in our daily lives. It is readily recognized on automobile body, panels, outdoor furniture, sewage and drinking water systems, construction and metal tools.

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