Isolation and Characterization of Escherichia coli from Tannery Wastewater with Special Reference to Chromium

Shoaib Ahmad Siddiqi*, Hina Qaiser, Rabia Iqbal, Naureen Naeem, Muhammad Amjad Khan, Asmara Imtiaz, Syeda Mona Hassan and Hammad Arshad

Abstract

ABSTRACT: With the progress of industries, environmental pollution with toxic heavy metals is spreading throughout the world. Technologies related to microbes may provide an alternative or addition to predictable method for the removal of these heavy metals. The present investigation deals with isolation and
description of chromium resistant bacteria from tannery wastewater taken from industrial area of Lahore, Pakistan. Firstly the leather industry effluent was examined for the total bacterial count and the presence of lactose fermenter and non lactose fermenter species on nutrient agar and MacConkey agar. Nutrient agar showed different colonies which were than identified by gram staining and colonies on MacConkey agar were identified by their colors as pink colonies show lactose fermenting species and off white or transparent colonies show presence of non lactose fermenting species. Potential heavy metal tolerant Escherichia coli was isolated by using Eosin methylene blue (EMB) agar medium supplemented with salts of chromium. The examination of morphological features of the obtained colonies authentically identified the isolate as Escherichia coli. The identified isolate was then exposed to different concentrations of chromium chloride to conclude the minimum inhibitory concentration (MIC) which was found out to be 160mg/mL.