Characterization of zinc stress response in Cyanobacterium Synechococcus sp. IU 625

Newby, Robert; Lee, Lee H.; Perez, Jose L.; Tao, Xiaofeng; Chu, Tin-Chun

doi:10.1016/j.aquatox.2017.03.005

Cited by 17 publications

(12 citation statements)

References 38 publications

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“…Synechococcus sp. IU 625 cultures were shown to be highly tolerant to 25 mg/L ZnCl 2 treatment, and a similar strain showed comparable growth to control when treated with 0.1 mg/L and 0.5 mg/L HgCl 2 [43,50]. Relatively and conversely, a total-protein profile of an Anabaena flos-aquae isolate showed progressive decrease upon treatment with increasing concentrations of CdCl 2 and CuCl 2 -with the highest concentrations presenting the most considerable biophysiological and biomass damage [57].…”

Section: Discussionmentioning

confidence: 99%

“…Our results are supported by the observations of cyanobacteria Synechococcus sp. IU 625, which showed a marked upregulation of smtA at 25 mg/L ZnCl 2 when analyzed via transcriptome analysis and qPCR analysis [50], and a relative, Synechococcus elongatus PCC 7942, which showed upregulation of smtA with Zn treatment [64]. The expression of mcyC was significantly upregulated at Day 12 for 0.1 and 0.25 mg/L ZnCl 2 treatment, while mcyE only showed slight upregulation for 0.1 and 0.25 mg/L ZnCl 2 treatment cells at this same time point ( Figure 4-middle and bottom row).…”

Section: Discussionmentioning

confidence: 99%

“…A sterile 1% zinc chloride (ZnCl 2 ) (Sigma-Aldrich, St. Louis, MO, USA) solution was added to each M. aeruginosa UTEX LB 2385 culture to yield relative ZnCl 2 concentrations: 0 mg/L, 0.1 mg/L, 0.25 mg/L, and 0.5 mg/L (0 µM, 0.734 µM, 1.835 µM, 3.669 µM, respectively), as described previously [50,70]. These ZnCl 2 concentrations were targeted through multiple growth curve analysis from past experiments, with concentrations as high as 10 mg/L ZnCl 2 (data not shown).…”

Section: Experimental Designmentioning

confidence: 99%

“…Aside from the observed zinc metal-complexing potential of MCs (MC-LR-Zn = −617 ± 7 kcal mol −1 ; MC-RR-Zn =−777 ± 9 kcal mol −1 ) [46], metallothioneins (MTs) are well documented metal-cation chelating, cysteine-rich proteins (<10 kDa) ubiquitously found in prokaryotes and eukaryotes [47,48]. MTs have been shown to be upregulated in different species of cyanobacteria when exposed to Zn 2+ or Cd 2+ concentrations while remaining relatively constant at basal levels [49,50]. Because of the variability of the MC synthetase gene cluster (encoding mcyABC-mcyD-J) in different cyanobacteria clades and within strains [51] and a relative conservation of MT cysteine domain sequences and motifs across cyanobacteria and bacteria [48], these genes may be possible quantification method candidates involving heavy metal zinc response and resistance in identified MC producing Microcystis species and strains.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Zinc on Microcystis aeruginosa UTEX LB 2385 and Its Toxin Production

Perez

Chu

2020

Toxins

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Cyanobacteria harmful algal blooms (CHABs) are primarily caused by man-made eutrophication and increasing climate-change conditions. The presence of heavy metal runoff in affected water systems may result in CHABs alteration to their ecological interactions. Certain CHABs produce by-products, such as microcystin (MC) cyanotoxins, that have detrimentally affected humans through contact via recreation activities within implicated water bodies, directly drinking contaminated water, ingesting biomagnified cyanotoxins in seafood, and/or contact through miscellaneous water treatment. Metallothionein (MT) is a small, metal-sequestration cysteine rich protein often upregulated within the stress response mechanism. This study focused on zinc metal resistance and stress response in a toxigenic cyanobacterium, Microcystis aeruginosa UTEX LB 2385, by monitoring cells with (0, 0.1, 0.25, and 0.5 mg/L) ZnCl 2 treatment. Flow cytometry and phase contrast microscopy were used to evaluate physiological responses in cultures. Molecular assays and an immunosorbent assay were used to characterize the expression of MT and MC under zinc stress. The results showed that the half maximal inhibitory concentration (IC 50 ) was 0.25 mg/L ZnCl 2 . Flow cytometry and phase contrast microscopy showed morphological changes occurred in cultures exposed to 0.25 and 0.5 mg/L ZnCl 2 . Quantitative PCR (qPCR) analysis of selected cDNA samples showed significant upregulation of Mmt through all time points, significant upregulation of mcyC at a later time point. ELISA MC-LR analysis showed extracellular MC-LR (µg/L) and intracellular MC-LR (µg/cell) quota measurements persisted through 15 days, although 0.25 mg/L ZnCl 2 treatment produced half the normal cell biomass and 0.5 mg/L treatment largely inhibited growth. The 0.25 and 0.5 mg/L ZnCl 2 treated cells demonstrated a~40% and 33% increase of extracellular MC-LR(µg/L) equivalents, respectively, as early as Day 5 compared to control cells. The 0.5 mg/L ZnCl 2 treated cells showed higher total MC-LR (µg/cell) quota yield by Day 8 than both 0 mg/L ZnCl 2 control cells and 0.1 mg/L ZnCl 2 treated cells, indicating release of MCs upon cell lysis. This study showed this Microcystis aeruginosa strain is able to survive in 0.25 mg/L ZnCl 2 concentration. Certain morphological zinc stress responses and the upregulation of mt and mcy genes, as well as periodical increased extracellular MC-LR concentration with ZnCl 2 treatment were observed. Key Contribution: Zinc stress causes cyanotoxin production increase in M. aeruginosa UTEX LB 2385.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Zinc on Microcystis aeruginosa UTEX LB 2385 and Its Toxin Production

Perez

Chu

2020

Toxins

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“…Overnight culture with or without EGCG-S 250 µg/ml were pipetted into the well and allowed to incubate at 37°C for 4 days. Samples were prepared according to the procedure reported previously [29]. Finally, the samples were mounted onto a stub and coated with a thin layer of metal film using the Denton IV Sputter Coater before microscopic observation.…”

Section: Scanning Electron Microscopy (Sem)mentioning

confidence: 99%

Green Tea Polyphenol Epigallocatechin-3-Gallate-Sterate Inhibits the Growth of <em>Streptococcus mutans</em>: A Promising New Approach in Caries Prevention

Melok¹,

Lee²,

Yussof³

et al. 2018

Preprint

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Streptococcus mutans (S. mutans) is the main etiological bacteria present in the oral cavity that leads to dental caries. All of the S. mutans in the oral cavity form biofilms that adheres to the surfaces of teeth. Dental caries are infections facilitated by the development of biofilm. An esterified derivative of epigallocatechin-3-gallate (EGCG), epigallocatechin-3-gallate-sterate (EGCG-S) was used in this study to assess its ability to inhibit the growth and biofilm formation of S. mutans. The effect of EGCG-S on bacterial growth was evaluated with colony forming units (CFU) and log reduction; biofilm formation was qualitatively determined by Congo red assay, and quantitatively determined by crystal violet assay, fluorescence-based LIVE/DEAD assays to study the cell viability, and scanning electron microscopy (SEM) was used to evaluate the morphological changes. The results indicated that EGCG-S was able to completely inhibit growth and biofilm formation at concentrations of 250 µg/ml. Its effectiveness was also compared with a commonly prescribed mouthwash in the United States, chlorhexidine gluconate. EGCG-S was shown to be equally effective in reducing S. mutans growth as chlorhexidine gluconate. In conclusion, EGCG-S is potentially a natural anticariogenic agent by reducing bacterial presence in the oral cavity.

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