Characterization of iron Bacterium Gallionella ferruginea isolated from the drinking water of the collector wells in Northern Sri Lanka.

Abstract

The objective of the study was to isolate, identify and characterize the organism/s responsible for the brownish slime colour and bad odour of the water from the collector wells at Vallipuram area of the Northern Sri Lanka. The iron concentrations in the collector well samples that are free of fecal coliform bacteria, varied from 0.093 to 0.307 mg.l-1 during the day time. Based on the microscopic biochemical and molecular characterization, the bacterial strain isolated from the collector wells was identified as Gallionella ferruginea. They are gram negative kidney-shaped mycoplasmodial bodies found in clusters. The colonial growth was powdery, opaque and flat in elevation. The biochemical characterization showed the positive interpretation for indole and catalase tests while methyl red, citrate, Voges-Proskaeur, urease production, nitrate reduction, tyrosine utilization, acetoin production and oxidase tests showed negative. The bacteria were capable of fermenting glucose with the production of acid in anaerobic condition, but not in aerobic condition thus confirmed as Gallionella ferruginea. This bacterial strain grew well in iron added liquid media at temperatures between 25–40oC and the optimum growth was observed at 35oC. Though Gallionella grew well at a broad range pH values between 6.0–10.0, the optimum growth was obtained at neutral pH. Addition of NaCl in the iron added liquid media can inhibit the growth and multiplication of Gallionella ferruginea.