Extracts of Marine cyanobacteria stimulated somatic embryogenesis of Daucus carota L

Phytostimulation and biofertilization in wheat by cyanobacteria

Cyanobacteria are commonly used for the phytostimulation and biofertilization of agriculture crops due to their nitrogen-fixing ability. However, the contribution by their phytohormones has been neglected. This study focuses on the screening of rhizospheric and free-living cyanobacteria for in vitro phytohormones production and growth stimulation in wheat. Selected isolates were shown to release cytokinin and indole-3-acetic acid (IAA) by using UPLC coupled with MS/MS via an electrospray interface. The maximum cytokinin and IAA concentration was 22.7 pmol mg(-1) ch-a and 38 pmol mg(-1) ch-a, respectively, in the culture medium of Chroococcidiopsis sp. Ck4 and Anabaena sp. Ck1. The growth of wheat inoculated with cyanobacterial strains was stimulated under axenic as well as field conditions. Seed germination, shoot length, tillering, number of lateral roots, spike length, and grain weight were significantly enhanced in inoculated plants. The maximum increase in grain weight (43%) was demonstrated in wheat plants inoculated with Chroococcidiopsis sp. Ck4 under natural conditions. Positive linear correlation of cyanobacterial cytokinin with shoot length (r = 0.608; P = 0.01), spike length (r = 0.682; P = 0.01), and grain weight (r = 0.0.869; P = 0.01) was recorded. Similarly, cyanobacterial IAA was correlated with the root growth parameters shoot length (r = 0.588; P = 0.01), spike length (r = 0.0.689; P = 0.01), and weight of seeds (r = 0.480; P = 0.05). The endogenous phytohormones pool of the plant was enhanced significantly as a result of the plant-cyanobacteria association in the rhizosphere. It was concluded that cyanobacterial phytohormones are a major tool for improved growth and yield in wheat.

Effect of ultraviolet-A (UV-A) light on growth, photosynthetic activity and production of biopterin glucoside by the marine UV-A resistant cyanobacterium Oscillatoria sp

We have isolated a marine planktonic cyanobacterium Oscillatoria sp. NKBG 091600 which is resistant to ultraviolet-A (UV-A) irradiation. In response to UV-A irradiation this cyanobacterium produces high levels of a UV-A absorbing compound which was identified previously as biopterin glucoside. Here, we have investigated the effect of UV-A light intensity on growth, biopterin glucoside production and photosynthetic activity. Oscillatoria sp. NKBG 091600 could grow at UV-A intensities of up to 800 microW/cm2 and at 300 microW/cm2 could grow as well as in the absence of UV-A irradiation. In addition, pre-culture of cells with UV-A protected cells from UV-A induced inhibition of photosynthetic activity. Detection of biopterin glucoside levels in irradiated cells by HPLC demonstrated that after 10 h there was a rapid increase in biopterin glucoside content. This increase was dependent on the intensity on the intensity of the UV-A irradiation.

On-line monitoring of marine cyanobacterial cultivation based on phycocyanin fluorescence

A novel on-line fluorescence monitoring system for marine cyanobacterial cultivation was developed. This method is based on the measurement of intracellular phycocyanin content, which is the major light harvesting protein. A fluorescence spectrophotometer, equipped with a flow cell connected with a culture liquid recycling tube was used. Experiments were carried out using a marine unicellular cyanobacteria Synechococcus sp. NKBG 042902 isolated from Japanese coastal sea water. We have optimized excitation wavelength to avoid the light scattering, using non-pigmented old cells which no longer contained phycocyanin. At an excitation wavelength of 590 nm, light scattering was minimized. Viable cell concentration could be measured in the range of 2 x 10(6) to 2 x 10(8) cells per ml, without pronounced light scattering. Continuous monitoring of marine cyanobacteria cultivation was performed. Cell concentrations were determined by both culture fluorescence and by using a hemacytometer. A good linear correlation was obtained. We conclude that on-line monitoring of cyanobacterial culture fluorescence based on phycocyanin is a rapid, efficient and also versatile method for determining viable cell concentration.