OBJECTIVETo observe the effects of iron and phosphorus on Microcystis physiological reactions.

METHODSThe experimental conditions were chosen as the light dark cycles of 16 h 8 h, 12 h 12 h, and 8 h 16 h. The cell change of morphology and life history, cell number, cell color, and cell area of Microcystis were analyzed quantitatively. According to the resource competition and Monod equation, Microcystis kinetics of phosphorus and iron were also examined.

RESULTSThe longer light time caused more special cell division, slower growth rate, and easier change of bigger cell area. The color of alga was changed from green to brown. Ks and micromax of phosphorus absorption were 0.0352 mircomol x L(-l) and 0.493 d(-1), respectively. Those of iron absorption were 0.00323 micromol x L(-1) and 0.483 d(-1).

CONCLUSIONMicrocystis bloom is more dominant than other algae.

Iron ; physiology ; Light ; Microcystis ; metabolism ; Phosphorus ; physiology

Microcystis aeruginosa, a type of algal bloom microalgae, is widely distributed in water, causing serious deteriorated effects on humans and the ecological environment. As a biocontrol microorganism, Bacillus subtilis can synthesize various bioactive substances through non-ribosomal peptide synthetase, to inhibit the growth of M. aeruginosa. Thus, it is imperative to investigate the non-ribosomal peptide (NRP) metabolites of B. subtilis fmb60. Three NRP metabolites from B. subtilis fmb60 including bacillibactin, surfactin and fengycin were extracted and identified by genome mining technology. The growth inhibition of M. aeruginosa was studied by adding various concentrations of NRP metabolites. The half-effect concentration value (EC50.4 d) of M. aeruginosa was 26.5 mg/L after incubation for 4 days. With the increasing concentration, the inhibitory effects of NRP metabolites of B. subtilis fmb60 on M. aeruginosa was enhanced significantly. Compared with the control group, with the addition of 50 mg/L NRP metabolites to the M. aeruginosa, the content of Fv/Fm, Fv/Fo and Yield parameter after cultured for 4 days were decreased by 2.8%, 1.7% and 2.0%, respectively. Those findings indicate that the NRP metabolites of B. subtilis fmb60 can significantly inhibit the photosynthesis and metabolism of M. aeruginosa, which provides a theoretical foundation for the development of biological algae inhibitor of B. subtilis.
Bacillus subtilis ; Humans ; Microcystis ; Peptides ; Photosynthesis

Gas vesicles are a unique class of gas-filled protein nanostructures which are commonly found in cyanobacteria and Halobacterium. The gas vesicles may scatter sound waves and generate harmonic signals, which enabled them to have the potential to become a novel ultrasound contrast agent. However, the current hypertonic cracking method for isolating gas vesicles contains tedious operational procedures and is of low yield, thus not suitable for large-scale application. To overcome these technical challenges, we developed a rapid and efficient method for isolating gas vesicles from Microcystis. The new H₂O₂-based method increased the yield by three times and shortened the operation time from 24 hours to 7 hours. The H₂O₂ method is not only suitable for isolation of gas vesicles from laboratory-cultured Microcystis, but also suitable for colonial Microcystis covered with gelatinous sheath. The gas vesicles isolated by H₂O₂ method showed good performance in ultrasound contrast imaging. In conclusion, this new method shows great potential for large-scale application due to its high efficiency and wide adaptability, and provides technical support for developing gas vesicles into a biosynthetic ultrasonic contrast agent.
Contrast Media ; Cyanobacteria ; Hydrogen Peroxide ; Microcystis ; Proteins/chemistry*

To know the value of the solubilization method using tissue solubilizer Soluene-350 in diagnosis of drowning, mice (ICR) were drowned artificially with the fresh water of Chungju district. Chlorophyta (or green algae), such as Oocystis and Eudorina, as well as diatoms, such as Diatoma, Synedra and Cyclotella were detected with other algae including Microcystis, Oscillatoria, Trachlomonas, Altenaria and Cephalodella in the water of Daeje-ji(Dae-je pond). This method is useful in detection of green algae and other kinds of algae for diagnosis of drowning in submerged bodies among legal autopsy cases.
Animals ; Autopsy ; Chlorophyta* ; Chungcheongbuk-do* ; Diagnosis* ; Diatoms ; Drowning* ; Fresh Water ; Mice ; Microcystis ; Oscillatoria ; Rivers* ; Water

OBJECTIVETo isolate and characterize indigenous algicidal bacteria and their algae-lysing compounds active against Microcystis aeruginosa, strains TH1, TH2, and FACHB 905.

METHODSThe bacteria were identified using the Biolog automated microbial identification system and 16S rDNA sequence analysis. The algae-lysing compounds were isolated and purified by silica gel column chromatography and reverse-phase high performance liquid chromatography. Their structures were confirmed by Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FT-IR) spectroscopy. Algae-lysing activity was observed using microscopy.

RESULTSThe algae-lysing bacterium LTH-2 isolated from Lake Taihu was identified as Serratia marcescens. Strain LTH-2 secreted a red pigment identified as prodigiosin (C20H25N3O), which showed strong lytic activity with algal strains M. aeruginosa TH1, TH2, and FACHB 905 in a concentration-dependent manner. The 50% inhibitory concentration (IC50) of prodigiosin with the algal strains was 4.8 (± 0.4)× 10⁻² μg/mL, 8.9 (± 1.1)× 10⁻² μg/mL, and 1.7 (± 0.1)× 10⁻¹ μg/mL in 24 h, respectively.

CONCLUSIONThe bacterium LTH-2 and its pigment had strong Microcystis-lysing activity probably related to damage of cell membranes. The bacterium LTH-2 and its red pigment are potentially useful for regulating blooms of harmful M. aeruginosa.

Anti-Bacterial Agents ; pharmacology ; Bacteria ; classification ; genetics ; metabolism ; Lakes ; Microcystis ; growth & development ; Phylogeny

OBJECTIVEAttempting to isolate and cultivate the microcytin-RR-producing cyanobacteria from natural blooms as well as to further investigate some characteristics of their growth and metabolite toxicity.

METHODSCapillary-pipette method was used to isolate wild Microcystis strains collected from eutrophicated lakes. The isolated strains were cultured in BG11 media at (25 ± 1) °C, under 2 000 lx illumination of fluorescent light with a light-dark rhythm of 12-12 h. The growth curve was observed by measuring optical density of culture suspension, toxin-related genes and the metabolite toxins were identified separately by PCR and HPLC, and its acute toxicity was carried out by orally administered toxins to Kunming (KM) mice.

RESULTSOne of five toxigenic strains from 198 collected samples was confirmed to be a MC-RR producing blue-green alga by existing two specific toxin-synthesized enzyme genes and showing specific chromatographic peak of the toxin compared with standard MC-RR through both PCR and HPLC methods. The toxic strain was classified as Microcystin aeruginosa by morphologic and phylogenetic tree analysis. The growth length of the strain lasted nearly 81 days with 55-60 days' exponential phase and the maximal concentration of 5.52 × 10⁷ cell/ml. The LD50 of the MC-RR to the KM mice ranged from 10.75 mg/kg to 13.45 mg/kg of body weight. As a result of the acute toxicity, the enzymatic indexes in serum such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) were significantly higher than those in the control group. The levels of ALT, AST, ALP and LDH in the treated group at 45 min were (157.08 ± 20.38), (333.00 ± 68.53), (392.70 ± 89.59) and (1 071.13 ± 160.22) U/L respectively, and at 4 h were (514.68 ± 156.87), (593.15 ± 40.41), (618.55 ± 208.76) and (2 281.72 ± 866.67) U/L respectively, and meanwhile the values of ALT, AST, ALP and LDH in the control group were (40.30 ± 4.89), (142.70 ± 26.59), (56.90 ± 11.89) and (509.50 ± 94.75) U/L separately (t values at 45 min were -11.20, -5.77, -7.38, -6.60 respectively, and at 4 h were -6.04, -20.21, -5.35, -4.07 respectively, P values were all <0.01). The liver coefficient in the treated group at 45 min and 4 h were 6.855 ± 0.225 and 8.409 ± 0.276, significantly higher than that (5.784 ± 0.286) in the control group (t values were -3.96 and -12.22, P values were both <0.01). The histopathological changes of liver were hyperemia obviously.

CONCLUSIONIsolated from the bloom waters, a strain of Microcystis aeruginosa is obtained with characteristics of longer growth duration, positive microcystin synthetase genes, and dominant production of MC-RR. The LD50 of the extracted MC-RR administered by oral route to mice is (12.10 ± 1.35) mg/kg of body weight, and liver is the target organ of MC-RR. The existence and potential risk of MC-RR in China cannot be ignored.

Animals ; China ; Chromatography, High Pressure Liquid ; Cyanobacteria ; Hyperemia ; Lakes ; Liver ; Mice ; Microcystins ; Microcystis ; Phylogeny

Microcystin is one of the monocyclic heptapeptides produced primarily by microcystis aeruginosa. Recent studies suggest that microcystin can induce cell apoptosis, as well as oxidative stress and mitochondrial alteration. Studies also indicate that Bcl-2 family and p53 may play an important role in the apoptosis induced by microcystin.
Animals ; Apoptosis ; physiology ; Humans ; Microcystins ; toxicity ; Microcystis ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Tumor Suppressor Protein p53 ; metabolism

OBJECTIVETo investigate the effect of iron on the growth, physiology and photosynthesis of cyanobacteria.

METHODSA gradient of iron concentrations was employed to investigate the growth, photo-pigments (chlorophyll A and phycocyanin), and cell chemical contents (C, N, P) of Microcystis aeruginosa in response to different iron additions.

RESULTSThe specific growth rate during the exponential growth phase, as well as the cell chlorophyll A and the phycocyanin content, was limited by iron below 12.3 tmol Fe x L(-1). The growth was inhibited when the iron concentration was at 24.6 micromol Fe x L(-1). The cell chlorophyll A and the phycocyanin content were saturated when the iron concentration was above 12.3 micromol Fe x L(-1) and declined slightly at 24.6 micromol Fe x L(-1). At a low iron concentration (about 6.15 micromol Fe x L(-1) and less), the cell nitrogen and carbohydrate content were iron limited, and the variation of the cell phosphorus content was similar to that of the nitrogen and carbohydrate, with a transition point of 12.3 micromol Fe x L(-1).

CONCLUSIONThe variation of cynobacteria growth is synchronous with that of the photo-pigments or the cell chemical content, and there exist relationships among photosynthesis, growth and internal chemical content, which could be useful for the growth estimation from the cell characteristics.

Carbohydrates ; analysis ; Culture Media ; chemistry ; Dose-Response Relationship, Drug ; Iron ; pharmacology ; Microcystis ; chemistry ; cytology ; drug effects ; physiology ; Nitrogen ; analysis ; Phosphorus ; analysis