Complete Genome Sequence of Microcystis aeruginosa FD4, Isolated from a Subtropical River in Southwest Florida

Urakawa, Hidetoshi; Hancock, Taylor L.; Steele, Jacob H.; Dahedl, Elizabeth K.; Urakawa, Haruka  E.; Ndungu, Luka K.; Krausfeldt, Lauren E.; Rosen, Barry H.; Lopez, Jose V.

doi:10.1128/mra.00813-20

Cited by 6 publications

(6 citation statements)

References 13 publications

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“…We then performed a BLAST search using the BLASTN algorithm to evaluate the conservation of the nucleotide sequence extending from the beginning of the first border repeat to the end of the second repeat across other bacteria. The results showed the conservation of this sequence with more than 90% only in three other M. aeruginosa strains: the analyzed PCC 7806 strain, another PCC 7806 strain designated PCC 7806SL (Zhao et al, 2018) and the recently sequenced FD4 strain (Urakawa et al, 2020). In these strains, the border repeats were conserved and surrounded the TA locus.…”

Section: Resultsmentioning

confidence: 88%

The Cysteine Protease MaOC1, a Prokaryotic Caspase Homolog, Cleaves the Antitoxin of a Type II Toxin-Antitoxin System

2021

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The bloom-forming cyanobacterium Microcystis aeruginosa is known for its global distribution and for the production of toxic compounds. In the genome of M. aeruginosa PCC 7806, we discovered that the gene coding for MaOC1, a caspase homolog protease, is followed by a toxin-antitoxin module, flanked on each side by a direct repeat. We therefore investigated their possible interaction at the protein level. Our results suggest that this module belongs to the ParE/ParD-like superfamily of type II toxin-antitoxin systems. In solution, the antitoxin is predominantly alpha-helical and dimeric. When coexpressed with its cognate toxin and isolated from Escherichia coli, it forms a complex, as revealed by light scattering and affinity purification. The active site of the toxin is restricted to the C-terminus of the molecule. Its truncation led to normal cell growth, while the wild-type form prevented bacterial growth in liquid medium. The orthocaspase MaOC1 was able to cleave the antitoxin so that it could no longer block the toxin activity. The most likely target of the protease was the C-terminus of the antitoxin with two sections of basic amino acid residues. E. coli cells in which MaOC1 was expressed simultaneously with the toxin-antitoxin pair were unable to grow. In contrast, no effect on cell growth was found when using a proteolytically inactive MaOC1 mutant. We thus present the first case of a cysteine protease that regulates the activity of a toxin-antitoxin module, since all currently known activating proteases are of the serine type.

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Section: Resultsmentioning

confidence: 88%

The Cysteine Protease MaOC1, a Prokaryotic Caspase Homolog, Cleaves the Antitoxin of a Type II Toxin-Antitoxin System

2021

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“…Microcystis aeruginosa strains used in this study are listed in Table 1 along with isolation location, ecological characteristics, as well as axenic or nonaxenic conditions. Microcystis strains FD4, HC1, and AL2 were isolated from the Caloosahatchee River and its branching waterways in the 2018 bloom event [6]. Microcystis were identified based on microscopic observation using a compound microscope (OMAX MD82ES10) and genomic characterization.…”

Section: Organisms and Cultured Conditionsmentioning

confidence: 99%

“…NIES-88, 90, 102, 843, and 4325 were obtained from the Microbial Culture Collection, National Institute for Environmental Studies (NIES), Tsukuba, Japan (Table 1). Genomes of five of the M. aeruginosa strains used in this study (FD4, NIES-843, NIES-88, NIES-4325, and NIES-102) have been sequenced and the reported genome size ranged from 3.88 Mb (NIES-4325) to 5.87 Mb (NIES-102) [6,[18][19][20][21]. NIES-102 was originally reported as Microcystis viridis, one of five commonly reported morphospecies of Microcystis (M. aeruginosa, M. viridis, M. novacekii, M. ichthyoblabe, and M. wesenbergii) [22].…”

Section: Organisms and Cultured Conditionsmentioning

confidence: 99%

“…Lake Okeechobee, the largest lake in the Southern United States, and its connecting waterways (the Caloosahatchee River and Saint Lucie River) frequently experience Microcystis blooms [3,4]. Recent cyanoHABs in Lake Okeechobee and both waterways led to the declaration of a state of emergency in 2016 and 2018 [4][5][6][7]. Nutrient reduction is currently considered the best strategy to reduce bloom events; however, these strategies can take many years to show positive results [7].…”

Section: Introductionmentioning

confidence: 99%

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Differential Effects of Hydrogen Peroxide and L-Lysine Treatments on the Growth of Freshwater Cyanophyta and Chlorophyta

Dahedl

Urakawa

2023

Ecologies

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Harmful cyanobacterial blooms of the toxin-producing Microcystis have become a growing problem for Southwest Florida freshwater bodies. Recently, a 2016 bloom in Lake Okeechobee and a 2018 bloom in the Caloosahatchee River both led to the declaration of a state of emergency for the state of Florida. Fast-acting suppression methods are needed to protect residents and wildlife. Hydrogen peroxide and L-lysine have shown promising results in selectively inhibiting the growth of Microcystis aeruginosa and are more ecologically friendly due to fast degradation in water or the biological enhancement of nontarget organisms, respectively. We further explored the use of hydrogen peroxide, L-lysine, and combined treatments of both chemicals, which have never been tested before, for the rapid suppression of Microcystis. We assessed the susceptibility of seven M. aeruginosa strains and six other phytoplankton (Cyanobium spp., Synechococcus sp., Dolichospermum planctonica, Mychonastes homosphaera, and Chromochloris zofingiensis) commonly found in Florida, and revealed that susceptibility was diverse. All three treatments were effective at inhibiting the growth of M. aeruginosa, mixed treatments (16.7 mg/L hydrogen peroxide: 8 mg/L L-lysine) were most effective with a median growth inhibition ratio of 94.2% on the last day of the experiment, while hydrogen peroxide (16.7 mg/L) (83.8%) and L-lysine (8 mg/L) (78.5%) were less so. We found axenic M. aeruginosa to be significantly more sensitive to hydrogen peroxide when compared with nonaxenic strains (p < 0.01, n = 18). L-lysine was found to be significantly more toxic to M. aeruginosa than other examined cyanobacteria and chlorophyte strains at the end of the experiment (p < 0.001, n = 33), demonstrating its specificity to this cyanobacterium, while hydrogen peroxide and mixed treatments had varying effects on the other tested phytoplankton.

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“…Microcystis is prevalent in Florida freshwaters (Williams et al, 2007;Burns, 2008) although toxicity levels are highly variable (Lefler et al, 2020). It forms extensive, reoccurring blooms in the diverse freshwater environments throughout the state, including the St. Johns River (Williams et al, 2007) and Lake Okeechobee (Ramani et al, 2012;Kramer et al, 2018) where blooms are released through water management practices into its tributaries, the St. Lucie (Oehrle et al, 2017;Kramer et al, 2018) and Caloosahatchee (Urakawa et al, 2020;Metcalf et al, 2021) Rivers. Microcystins are found year-round in these systems (Williams et al, 2007).…”

Section: Microcystis Speciesmentioning

confidence: 99%

Florida’s Harmful Algal Bloom (HAB) Problem: Escalating Risks to Human, Environmental and Economic Health With Climate Change

Heil

Muni-Morgan

2021

Front. Ecol. Evol.

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Harmful Algal Blooms (HABs) pose unique risks to the citizens, stakeholders, visitors, environment and economy of the state of Florida. Florida has been historically subjected to reoccurring blooms of the toxic marine dinoflagellate Karenia brevis (C. C. Davis) G. Hansen & Moestrup since at least first contact with explorers in the 1500’s. However, ongoing immigration of more than 100,000 people year–1 into the state, elevated population densities in coastal areas with attendant rapid, often unregulated development, coastal eutrophication, and climate change impacts (e.g., increasing hurricane severity, increases in water temperature, ocean acidification and sea level rise) has likely increased the occurrence of other HABs, both freshwater and marine, within the state as well as the number of people impacted by these blooms. Currently, over 75 freshwater, estuarine, coastal and marine HAB species are routinely monitored by state agencies. While only blooms of K. brevis, the dinoflagellate Pyrodinium bahamense (Böhm) Steidinger, Tester, and Taylor and the diatom Pseudo-nitzschia spp. have resulted in closure of commercial shellfish beds, other HAB species, including freshwater and marine cyanobacteria, pose either imminent or unknown risks to human, environmental and economic health. HAB related human health risks can be classified into those related to consumption of contaminated shellfish and finfish, consumption of or contact with bloom or toxin contaminated water or exposure to aerosolized HAB toxins. While acute human illnesses resulting from consumption of brevetoxin-, saxitoxin-, and domoic acid-contaminated commercial shellfish have been minimized by effective monitoring and regulation, illnesses due to unregulated toxin exposures, e.g., ciguatoxins and cyanotoxins, are not well documented or understood. Aerosolized HAB toxins potentially impact the largest number of people within Florida. While short-term (days to weeks) impacts of aerosolized brevetoxin exposure are well documented (e.g., decreased respiratory function for at-risk subgroups such as asthmatics), little is known of longer term (>1 month) impacts of exposure or the risks posed by aerosolized cyanotoxin [e.g., microcystin, β-N-methylamino-L-alanine (BMAA)] exposure. Environmental risks of K. brevis blooms are the best studied of Florida HABs and include acute exposure impacts such as significant dies-offs of fish, marine mammals, seabirds and turtles, as well as negative impacts on larval and juvenile stages of many biota. When K. brevis blooms are present, brevetoxins can be found throughout the water column and are widespread in both pelagic and benthic biota. The presence of brevetoxins in living tissue of both fish and marine mammals suggests that food web transfer of these toxins is occurring, resulting in toxin transport beyond the spatial and temporal range of the bloom such that impacts of these toxins may occur in areas not regularly subjected to blooms. Climate change impacts, including temperature effects on cell metabolism, shifting ocean circulation patterns and changes in HAB species range and bloom duration, may exacerbate these dynamics. Secondary HAB related environmental impacts are also possible due to hypoxia and anoxia resulting from elevated bloom biomass and/or the decomposition of HAB related mortalities. Economic risks related to HABs in Florida are diverse and impact multiple stakeholder groups. Direct costs related to human health impacts (e.g., increased hospital visits) as well as recreational and commercial fisheries can be significant, especially with wide-spread sustained HABs. Recreational and tourism-based industries which sustain a significant portion of Florida’s economy are especially vulnerable to both direct (e.g., declines in coastal hotel occupancy rates and restaurant and recreational users) and indirect (e.g., negative publicity impacts, associated job losses) impacts from HABs. While risks related to K. brevis blooms are established, Florida also remains susceptible to future HABs due to large scale freshwater management practices, degrading water quality, potential transport of HABs between freshwater and marine systems and the state’s vulnerability to climate change impacts.

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Complete Genome Sequence of Microcystis aeruginosa FD4, Isolated from a Subtropical River in Southwest Florida

Cited by 6 publications

References 13 publications

The Cysteine Protease MaOC1, a Prokaryotic Caspase Homolog, Cleaves the Antitoxin of a Type II Toxin-Antitoxin System

The Cysteine Protease MaOC1, a Prokaryotic Caspase Homolog, Cleaves the Antitoxin of a Type II Toxin-Antitoxin System

Differential Effects of Hydrogen Peroxide and L-Lysine Treatments on the Growth of Freshwater Cyanophyta and Chlorophyta

Florida’s Harmful Algal Bloom (HAB) Problem: Escalating Risks to Human, Environmental and Economic Health With Climate Change

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