Farzaneh Zandi, Ramin Hossini, Neda Soltani, , ,
Volume 12, Issue 3 (11-2012)
Abstract
Oil pollutions as a consequence of increasing consumption of petroleum, have a tremendous effect on water and soil ecosystems and their microflora. In this study the diversity in physiological parameters, including growth rate, photosynthesis, chlorophyll-a and phycobiliproteins content, between cyanobacterial strains flora isolated from oil-polluted and non-polluted areas, were assessed. To this end, strains were isolated and purified. The experiments were carried out on logarithmic phase cultures of the isolates in suitable liquid media. The chlorophyll and phycobiliproteins contents were determined using a colorimetric method. Photosynthesis was measured by Oxyview apparatus. Growth rates were calculated based on dry weights. Under laboratory conditions, the photosynthesis activity and the chlorophyll content of isolates from oil-polluted sites were significantly lower than non-polluted isolates. On the other hand, the growth rate average of strains from oil-polluted sites was significantly higher than non-polluted strains. Also despite the higher phycobiliproteins content in non-polluted isolates, there was no significant difference in any of these pigments between the two groups. Altogether the results showed that in response to petroleum stress, the cyanobacteria restore the decrease in their chlorophyll content and photosynthesis activity by increasing their biomass. In fact the response is the reflects of restructuring cyanobacterial flora from sensitive autotrophic species to oil-pollution resistant mixotrophic species in the polluted ecosystems that in addition to photosynthesis are able to use crude oil as an energy source for their growth requirements, hence overcome the energy loss due to reduction of photosynthesis and even increase growth rate than non-oil-pollution isolates.
Volume 18, Issue 56 (9-2006)
Abstract
Due to the importance of benthic cyanobacteria in nitrogen fixation in paddyfields, the physiological responses of Fischerella ambigua FS 18 to salinity (NaCl 0, 0.5 & 1%) were investigated. Results indicated that growth rate was higher in control and that NaCl did not inhibit growth of other treatments. Similar responses were seen in the case of other physiological processes. Chlorophyll was declined with increasing salinity. Phycobiliproteins (PBP), phycocyanin (PC) and allophycocyanin (APC) were at least in 0.5% but the differences were not significant. The light-saturated photosynthetic rate was higher in control and decreased with increasing in salinity. With respect to nitrogenase activity, the highest rate was in control and the cultures with higher growth rates reached to the maximum level at a shorter time. There was no significant difference between 0.5 and 1% in relation to nitrogenase activity.
