Dr Caitlin Romanis

Municipal wastewater treatment facilities (WWTFs) are prone to the proliferation of cyanobacterial species which thrive in stable, nutrient-rich environments. Dense cyanobacterial blooms frequently disrupt treatment processes and the supply of recycled water due to their production of extracellular polymeric substances, which hinder microfiltration, and toxins, which pose a health risk to end-users. A variety of methods are employed by water utilities for the identification and monitoring of cyanobacteria and their toxins in WWTFs, including microscopy, flow cytometry, ELISA, chemoanalytical methods, and more recently, molecular methods. Here we review the literature on the occurrence and significance of cyanobacterial blooms in WWTFs and discuss the pros and cons of the various strategies for monitoring these potentially hazardous events. Particular focus is directed towards next-generation metagenomic sequencing technologies for the development of site-specific cyanobacterial bloom management strategies. Long-term multi-omic observations will enable the identification of indicator species and the development of site-specific bloom dynamics models for the mitigation and management of cyanobacterial blooms in WWTFs. While emerging metagenomic tools could potentially provide deep insight into the diversity and flux of problematic cyanobacterial species in these systems, they should be considered a complement to, rather than a replacement of, quantitative chemoanalytical approaches.

Two cyanobacterial strains, one collected from an epidermal mat present on a dead bottlenose dolphin and the other as a bioaerosol 457 m (1500¿ft) above the river, were recently analysed from the St. Johns River, Jacksonville, Florida, USA. Both samples had major phenotypic plasticity which confused morphological identification. Amplicon sequencing of the 16S rRNA gene from the isolates revealed that both samples were closely aligned (branch bootstrap support¿=¿100%) with the recently erected genus Komarekiella. Whole genome sequencing and phylogenetic construction also supported the isolation of a new species of cyanobacteria branching from the Nostoc clade. A total evidence approach of molecular, genetic, and ecological examination of these strains supported the erection of a new species, Komarekiella delphini-convector. A prior study determined that the dolphin with the epidermal mat had low levels of microcystins/nodularins (MCs/NODs) in the hepatic tissue. To investigate whether these toxins originated from the epidermal mat, immunoassay (ELISA) and 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) techniques were conducted on the original mat and subsequent culture samples. The results from both analyses were not conclusive. Genome mining was conducted and revealed diverse biosynthetic capabilities of this species but could not support toxin-producing potential. Further analytical work is required to determine the pathogenic capacity of this epizoic species.