Effect of glyphosate toxicity on growth, pigment and alkaline phosphatase activity in cyanobacterium Anabaena doliolum: a role of inorganic phosphate in glyphosate tolerance.

Response of glyphosate toxicity on photoautotrophic cyanobacterium A. doliolum and its mutant strain was investigated. Chlorophyll a content of both the wild type and mutant strain in the presence of glyphosate (N-phosphonomethyl glycine) initially showed an increasing trend when supplemented with Pi and a declining tendency under the Pi-starved condition. The results suggested that both the wild type and mutant strains were more sensitive to glyphosate in the absence of phosphate. Alkaline phosphatase activity of wild type strain in the presence of Pi, enhanced in response to addition of glyphosate (40 microg/ml), but the activity remained unaltered by addition of glyphosate in the Pi-starved cells, whereas the alkaline phosphatase activity in the mutant strain under both Pi-starved as well as unstarved conditions was stimulated (approximately 5.4 and 3.1-fold, respectively) by addition of glyphosate. The results on alkaline phosphatase activity indicated a glyphosate-induced depletion in the phosphate content of the cells, particularly in the mutant strain, as evident from the stimulated activity of alkaline phosphatase. It is suggested that enzyme activity in the Pi-starved wild type cells may not be influenced any further by glyphosate, as cellular phosphate reserve might not be available for further depletion.

Effect of some essential oils on microorganisms.

The essential oils tested viz., Cardiaca Oil, Mentha Oil, Artemisia Oil and Geranium Oil against pathogenic bacterial and fungal strains. Significant activity of all oils was found against all microorganisms. All the four oils showed a higher inhibition against all the microorganisms, except S. epidermidis at different level of concentrations used (1000 ppm and 500 ppm). It is clearly indicated that inhibition activity increased approximately 1 to 2 folds at 1000 ppm concentration as compared to 500 ppm. S. epidermidis has shown resistant towards all the oils at both the concentration while M. smegmatis and S. mutans have shown higher inhibition as compared to S. epidermidis.