evaluation of the microbial quality of the river nile waters at damietta branch, egypt

Abstract

This study aims to the evaluation of the microbial quality of the River Nile water at Damietta Branch. Water samples were taken from the branch, during the period from autumn, 2005 till the summer of 2006. Some environmental parameters such as temperature, transparency, depth and pH were monitored. In addition, the bacteriological analyses involved total viable bacterial counts (TVBCs), total coliforms (TC) and estimation of faecal coliforms (FC), faecal streptococci and pathogenic bacteria. The results of physicochemical parameters showed that the temperature values varied from 17°C to 25°C and the transparency from 40cm to 220cm. Whereas, the depths varied from 3m to 25m and pH values from 7.24 to 8.44. The bacteriological analyses showed that TVBCs ranged from 10.8x107 to 150 x107 cfu/ml and from 8.8x107 to152 x107cfu/ml at 22°C and 37°C, respectively. However, maximum counts were recorded during summer and the minimal were detected in winter. The results of the faecal indicators counts revealed that their densities increased from up- to down stream. The pathogenic bacteria were identified using API 20E strip system (BioMereux). One hundred pathogenic bacterial isolates representing eleven genera were identified to species level. This included, the following suggested names: Esherichia coli (16%), Klebsiella pneumoniae (14%), Pseudomonas aeruginosa (12%), Pseudomonas flourcsence (4%), Salmonella colerasuis (11%), Shigella sp. (9%), Serratia liquefaciens (8%), Proteus vulgaris (8%), Acinetobacter sp.(7%), Brenneria nigrifluens (5%), Flavimonas oryzihabitans (3%) and Chryseomonas lutecla (3%). The results of the present investigation revealed that, the River Nile water at Damietta Branch was subjected to sewage pollution during the study period.