Assessment of indicator microorganisms and fungi: Health risk in the Saen Saeb canal, Thailand

Abstract

The Saen Saeb canal, which is located at the center of Bangkok, Thailand, is mainly used for public transportation to avoid heavy rush-hour traffic. The canal water is heavily polluted by human activity and hardly any aquatic life can be found. Apart from the reports of coliform bacteria by the National Statistical Office in 2012, no other studies to date have been conducted in order to characterize the microorganisms present in the Saen Saeb canal. Therefore, this study aimed to investigate the prevalence of indicator microorganisms and common microorganisms in the Saen Saeb canal water and surrounding air. Water and air samples were collected from 26 station ports along the entire length of the Saen Saeb canal at 4-month intervals during June 2013-May 2014. The overall ranges of the indicator bacteria were as follows: total coliforms at 0.10-9.12×104 cfu/100 mL, fecal coliforms at 0.10-1.49×104 cfu/100 mL, fecal streptococci and enterococci at 0-2.85×104 cfu/100 mL, total heterotrophic flora at 37°C at 0.64-6.8×10‑ cfu/100 mL, and Salmonella and Shigella at 0.04-1.75×104 cfu/ 100 mL. The total fungal count ranged from 0.12-0.233×103 cfu/ mL. The most abundant fungi belonged to the Phyla Ascomycota and Zygomycota. Coliphages (ϕPS23, ϕPF21, ϕCP31, ϕNN21, and ϕAS21) which represented the fecal contamination of enteric viruses were also obtained. Analysis of 26 samples from the air sampling stations surrounding the Saen Saeb canal indicated that the dominant airborne bacteria was Bacillus spp. The overall results showed that the Saen Saeb canal and its surrounding areas contained high levels of microorganisms, especially pathogenic microorganisms. To the best of our knowledge, this is the first report that determined the extent of microbial contamination in the Saen Saeb canal. The results of this study would help increase environmental public awareness and provide useful information for sustainable water resource management. © 2017, Chiang Mai University. All rights reserved.