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The impact of temperature and photosynthetically active radiation on the growth and pigments concentration in Baltic picocyanobacterium Synechococcus sp.

100%

Śliwińska-Wilczewska S., Cieszyńska A., Latała A.

Annales Universitatis Paedagogicae Cracoviensis Studia Naturae

2017

The experiments on three Baltic picocyanobacterial strains of Synechococcus (BA-120 – red strain, BA-124 – green strain and BA-132 – brown strain) were conducted at four scalar irradiances in Photosynthetically Active Radiation (PAR) and four temperature levels. The main aim of this work was to estimate the effect of environmental conditions (temperature and PAR) on cell concentration and photosynthetic pigments (Chlorophyll a – Chl a and Carotenoids – Car) contents. The ranges of PAR and temperatures were 10, 100, 190, 280 μmol m-2 s-1 and 10, 15, 20, 25ºC, respectively. The experiment was carried in a medium of salinity of 8. The number of Synechococcus sp. cells was determined using a BD Accuri™ C6 flow cytometer. The pigments contents were determined by a spectrophotometric method. In this work, it was found that elevated intensity and temperature have, on average, a positive effect on cell concentration for Synechococcus sp. The highest cells concentrations were noted at the highest PAR (280 µmol m-2 s-1) and the highest T (25ºC) for green and brown strains (BA-124 and BA-132, respectively) and at 190 µmol m-2 s-1 and 25ºC for red strain (BA-120). Comparing the strains at each PAR level and temperature, the highest cell concentration was noted in green strain (36·106 cell ml-1), while the lowest was observed in red strain (8·106 cell ml-1). In general, in the two strains of Synechococcus (BA-120 and BA-132), the highest Car and Chl a contents were observed at the lowest light intensity and the highest temperature. On the other hand, Car and Chl a maximum content in BA-124 were noted at the lowest light and temperature. The experiments on Synechococcus strains demonstrated their high capacity to acclimate to a wide range of PAR and temperature levels. The three strains of Synechococcus showed adaptation capabilities, since they were able to change the composition of their photosynthetic pigments to use light quantity better and to protect the cells from the unfavourable effect of elevated light and temperature.

Allelopathic activity of the Synechococcus sp. (Cyanobacteria, Chroococcales) on selected cyanobacteria species

86%

Śliwińska-Wilczewska S., Gergella K., Latała A.

Annales Universitatis Paedagogicae Cracoviensis Studia Naturae

2016

Picocyanobacterium Synechococcus sp. is very important but still poorly understood component of marine and freshwater ecosystems. In this study, the effect of single and multiple addition of cell-free filtrate obtained from Synechococcus sp. on selected cyanobacteria Synechocystis sp., Geitlerinema amphibium, Nodularia spumigena and Nostoc sp. was investigated. The species present in this work are groups of aquatic phototrophs known to co-occur in the Baltic Sea. The study showed that the picocyanobacterial cell-free filtrate inhibit the growth and changed the cell morphology of filamentous cyanobacteria G. amphibium, N. spumigena and Nostoc sp. It was shown that the addition of cell-free filtrate caused a decline of pigmentation and cell lysis of G. amphibium, N. spumigena and Nostoc sp. compared to the control culture. In addition, it was observed that the filtrate obtained from Synechococcus sp. did not affect the Synechocystis sp. It was found that the filtrate obtained from picocyanobacterium had the strongest effect on growth of G. amphibium, therefore for this cyanobacteria performed additional experiments to showed whether the filtrate affected also photosynthetic pigments, chlorophyll fluorescence and photosynthesis. The study proved that the picocyanobacterial allelopathic compounds reduce the efficiency of photosynthesis, which results in the inhibition of growth of target organisms. This way of interaction may explain the formation of almost monospecific cyanobacterial blooms in many aquatic ecosystems, including in the Baltic Sea.

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2 Annales Universitatis Paedagogicae Cracoviensis Studia Naturae

2 Latała A.

2 Śliwińska-Wilczewska S.

1 Cieszyńska A.

1 Gergella K.

1 2017

1 2016

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The impact of temperature and photosynthetically active radiation on the growth and pigments concentration in Baltic picocyanobacterium Synechococcus sp.

Allelopathic activity of the Synechococcus sp. (Cyanobacteria, Chroococcales) on selected cyanobacteria species