ساده سازي اندازه گيري فعاليت آلكالين فسفاتاز در خاك هاي هوا-خشك

چكيده انگليسي :

Abstract Alkaline phosphatase a well known phosphomonoesterase plays a vital role in P mineralization and supplying P to plants and that is of great importance in nutrient cycling and supporting soil fertility Soil enzymes in general are central to soil biological functionality Moreover they are quickly and precisely measured and have quick response to soil management practices Therefore soil enzymes have received considerable attentions to assess soil biological capabilities During last few decades many attempts have been made on developing new protocols regarding soil enzyme activity measurements and hence many simple precise quick procedures have been consequently developed However the debate is still open to make some more improvements in the soil enzyme activity measurement procedures Simplification of the soil enzyme activity measurement is continually received the attention of soil scientists In order to simplify the activity measurement of alkaline phosphatase in soil we hypothesized that toluene addition can be omitted and shaking can result in more consistent results In particular toluene is a carcinogenic dangerous chemical and its omission can be very helpful to make the lab environment safer Therefore the objectives of the study were i to replacing toluene addition with shaking and ii to re assess the accuracy and consistence of the modified procedure via measuring thermal stability of the enzyme Twenty two calcareous soils were collected from agricultural soils of Isfahan Province The soils were air dried and general soil physical and chemical characterization was performed Soil alkaline phosphatase was measured by the procedure that is extensively used around the world Tabatabai and Bremner 1969 The procedure is based on the colorimetric detection of paranitrophenol as a product of de esterification of para nitrophenyl phosphate under optimum conditions The activity of the enzyme was measured again by using shaking as an alternative for toluene addition Our results indicated that when soil and the solution were shaken during the one hour incubation no significant difference was observed as toluene addition was omitted Removing toluene addition increased the average of alkaline phosphatase activity in soils and that the coefficient of variation was decreased as shaking was added to the procedure The values obtained by the newly developed procedure was significantly correlated with the conventional protocol of alkaline phosphatase activity measurement r 0 76 P 0 001 Thermal stability of the soil enzyme was measured by both methods and our results indicated that significant decrease in the measured activity was observed by both procedures In both protocols some parts of the activity was still remained even when pretreatment temperature increased up to 120 C Therefore thermal stability assessment was successfully performed either by the convention or by the simplified method Overall we concluded that shaking can be considered as an alternative for toluene application in alkaline phosphatase in calcareous soils The reliability of the simplified method in acid soil and for acid phosphatase activity measurement warrant further researches Key words Alkaline phosphatase Toluene Shaking Thermal stability

گرامي زاده نائيني، مريم

ساده سازي اندازه گيري فعاليت آلكالين فسفاتاز در خاك هاي هوا-خشك

تولوئن , تكان دادن حين انكوباسيون , پايداري حرارتي