Development of a Potentially New Algaecide for Controlling Harmful Cyanobacteria Blooms Which is Ecologically Safe and Selective

Abstract

Harmful cyanobacterial blooms (HCBs) caused by Microcystis aeruginosa are of great concern as they negatively affect the aquatic environment and human health. Chemical methods could rapidly eradicate HCBs and have been used for many decades. However, many chemical reagents are not recommended to eliminate HCBs in the long term, given the possible destructive and toxic effects of the chemicals employed on non-target aquatic organisms. We developed a new algaecide, 2-((1,3,4-thiadiazol-2-yl)­thio)-N-(4-chlorophenyl) acetamide (Q2), to control harmful cyanobacteria while being environmentally friendly and selective. In our study, Q2 effectively inhibited cyanobacterial growth, especially of M. aeruginosa, but did not affect eukaryotic algae in test concentrations. A critical mechanism was revealed by transcriptome and metagenomic results showing that Q2 affects multiple cellular targets of cyanobacteria for HCB control, including the destruction of organelles, damage in the photosynthesis center, as well as inhibition of gas vesicle growth, and these changes can be highly relevant to the decrease of quorum-sensing functional KEGG pathways. Furthermore, Q2 did not affect the microbial composition and could recover the disrupted aquatic functional pathways in a short period. This is different from the impact on ecosystem functioning of the traditionally used harmful algaecide diuron. All these results verified that Q2 could be friendly to the aquatic environment, providing a new directional choice in managing HCBs in the future.

Plastoquinone synthesis inhibition by tetrabromo biphenyldiol as a widespread algicidal mechanism of marine bacteria

“…The RNA samples were then reverse transcribed into cDNA using the SuperScript First-Strand synthesis system with random hexamers for RT-PCR (Invitrogen, USA). PCR was performed with the following pair of 18 S rRNA gene primers, SSU0817F and 1196 R [ 65 ]. The PCR reaction system was as follows: 4 μl 5 × FastPfu buffer, 2 μL dNTPs (2.5 mM), 0.2 μL BSA, 0.8 μL each of forward and reverse primer (5 μM), 0.4 μL TransStart Fastpfu DNA Polymerase, 10 ng template DNA, and added double-distilled water to 20 μL.…”

Current and Previous Green Technologies, Their Efficiency, Associated Problems, and Success Rates to Mitigate M. aeruginosa in Aquatic Environments

“…They are considered to be relatively safe materials [62]. A novel environmentally safe and selective algaecide called 2-((1,3,4-thiadiazol-2-yl)thio)-N-(4-chlorophenyl) acetamide (Q2) was created to suppress M. aeruginosa blooms [10]. It was different from the impact on ecosystem functioning of the traditionally used harmful algaecide diuron.…”

“…The National Health and Medical Research Council (2008) established this as the red alert threshold for recreational water consumption in Australia, at which point New South Wales begins to take bloom management measures [9]. From the 1980s to 2022, Microcystis aeruginosa dramatically increased in frequency and abundance throughout the world, causing high levels of water contamination and affecting human health [10,11].…”

Design, Synthesis, and Bioassay for the Thiadiazole-Bridged Thioacetamide Compound as Cy-FBP/SBPase Inhibitors Based on Catalytic Mechanism Virtual Screening

“…Therefore, it is crucial to mitigate the threats of HCBs to ensure the protection of aquatic environments and the health of affected organisms . There are many ways to control HCBs, including physical control, chemical control, and biological control. − Chemical control is considered one of the most effective methods to solve the harm of HCBs. Among the existing chemical algicides, there are mainly heavy metal algicides represented by copper sulfate (CuSO 4 ), strong oxidant algicides represented by potassium permanganate and peroxide, and herbicide algicides represented by diuron and prometryn .…”