Phosphatase Activity of Non-Hair Forming Cyanobacterium Rivularia and Its Role in Phosphorus Dynamics in Deepwater Rice-Fields

Abstract

Abstract. Phosphatase activity of Rivularia strains II and I isolated from a deepwater rice field was studied. When grown under conditions of P-limitation the strains did not form hair and showed great variations in induction time and pattern of enzyme activity in relation to growth. Phosphomonoesterase activity (PMEase) was induced earlier in the Rivularia strain I which was maintained in high phosphate concentration in the medium before the study. Rivularia strain II on the other hand showed induction of PMEase activity after 3-4 days and this strain was maintained in low phosphorus concentrations in the medium before the study. The comparison of K m and V max values early in the growth phase showed that affinity of both PMEase (phosphomonester) and PDEase (phosphodiester) for the substrate was higher in early growth phase rather than in later stages suggesting that there is presence of more than one phosphatase enzymes in these organisms. The observations from the above study have important implications in rice fields where constant fluctuations in nutrients can be observed -especially by phosphorus in its most available form phosphate. Equal enzyme activity in both light and dark for the two strains (non hair-forming) implies that phosphatase activity may not be affected by changes in light regimes in rice fields which do occur due to the plant growth. This can in turn contribute significantly to maintain the growth of cyanobacteria for prolonged periods even under unfavorable conditions of phosphorus depletions. These strains of Rivularia can therefore biotechnologically exploited as biofertilizers (phosphatic fertilizer) when there is phosphorus deficiency. During the unfavorable conditions of phosphorus deficiency, phosphatase activity may play a significant role in providing phosphate for its own growth and for the rice plants.

Phosphatase activities of cyanobacteria as indicators of nutrient status in a Pyrenees river

“…The values of R 2 refer to the fit of the straight line of the transformations of the Michaelis-Menten equation and indicate the fit of the data to that transformation to consider this factor in short-term field assays. Similar results were found by Banerjee & John (2005) for two strains of Rivularia in which PMEase activity was the same in light and dark. Several of the laboratory results require more detailed study, especially the low rate of increase in PMEase activity of Rivularia with rise in temperature over the range 10-35°C, which suggests adaptation to the frequent temperature changes in nature.…”

Low algal diversity systems are a promising method for biodiesel production in wastewater fed open reactors

“…While growing algae outdoors is generally expensive, the cost of this method of cultivation can be greatly reduced by using wastewater as a medium for their growth (Ahrens and Sander 2010, Clarens et al 2010, Park et al 2011, Stockenreiter et al 2012. Algae can also produce a variety of high value compounds such as biodiesel and biofertilizer, without contributing to atmospheric carbon dioxide (Borowitzka 1995, Olaizola 2003, Banerjee and John 2005, Banerjee and Kushwaha 2005.…”