Cylindrospermopsin (CYN), a potent hepatotoxin produced by Cylindrospermopsis raciborskii has been detected in many drinking water supplies of Queensland. Irrespective whether the toxin occurs in the source water, water resource managers have to provide consumers with drinking water, free from cyanotoxins. Recent and ongoing research has demonstrated that CYN is removed during chemical treatment however some concern remains regarding the formation of potentially harmful disinfection byproducts. Biological degradation is an alternative method of degrading cyanotoxins during pretreatment of drinking water.

The aim of this study was to assess whether bacteria are capable of degrading CYN and even more so to isolate and culture organisms, which have the capacity to degrade CYN in water. The method used was based on a multistep enrichment and isolation technique. A sample of water that had previously demonstrated biodegradative activity for CYN was spiked with an aqueous C. raciborskii cellular extract.The water was then incubated at a constant temperature in the dark. Subsamples were regularly taken and analysed for CYN using HPLC/MS/MS to determine if degradation was occurring. Once log linear degradation was found a subsample was collected and was added to a medium containing purified CYN. The steps were repeated and when during the second run more than 80% of the CYN was degraded the sample was centifuged, supernatant decanted and the pellet washed several times. The cleaned pellet was resuspended and an aliquot added to a fresh medium containing purified CYN. This procedure was repeated several times. On the final enrichment an aliquot of pellet was streaked on to solidified medium containing purified CYN. Single colonies from these plates were transferred back into sterile medium containing purified CYN and toxin concentrations monitored to ensure isolation of CYN degradative bacteria was accomplished.

These bacterial isolates were subjected to numerous analyses to determine their identification. Initial results indicate all degradative orgainsms isolated were gram negative coccobacilli. Sequencing of the genome of these isolates is still in progress.