The Effect of on the Monitoring of Faecal Indicator Bacteria.

The survival of () bacteria, the most common faecal indicator bacteria (FIB), may be significantly affected by cyanobacteria present during a harmful algal bloom (HAB). Therefore, the effect of on the survival of FIB and coliforms was investigated. Microcosms containing two species of ( and ) were established and then inoculated with four reference strains of (ATCC 25922, 8739, 51813, and 11775) to explore the cyanobacteria-bacteria dynamics at a laboratory setting. Monitoring over several days showed normal growth of , with or without the presence of . However, was shown to dramatically decrease the survival of over time. Analysis of microcystin production by was found to correlate with loss of , suggesting a toxic effect of microcystins on bacteria. This phenomenon was also demonstrated for a natural consortium of and coliform bacteria by inoculating with contaminated lake water. The results indicate that the use of as FIB may be greatly compromised in the presence of spp. such as during a HAB when associated toxins are produced.