Study of the Urease enzyme activity and the some effect factors on urea hydrolyses in some agriculture soils in Ramadia

Abstract

The research has been carried out to study the existence, distribution and identified the isolated of urea hydrolysis bacteria and produced the urease from 30 samples have been collected from 6 regions agricultural soils felids between Ramadia and Heat city on the two sides of Euphrates river ( Gzeria and Zngora).3 regions for each Gzeria and Zngora that wheat and vegetable agriculture uses and wild, in the period march to July 2010. The samples were analyzed and limited 20 samples are positive for urea hydrolysis. The urease enzyme activity was also investigated, 5 isolates are belong to good urea hydrolysis bacteria have been selected and identified. The effects of some factors such as the temperatures, different concentrations of urea and different ratios of CaSO4. The results were as follows; The area of study was about 8000 ha., most soils’ had sandy loom texture , calcareous (CaCO3 18 – 23%), variation in gypsum content (2.53 – 14.12%), organic content (0.23 – 0.92%), soil salinity for agriculture fields (3.13 – 3.50 ds.m-1) but the wild soils increase to 4.52 ds.m-1. Urea applied was almost totally hydrolyzed to ammonia in all soils tested with 30 days and the best urease activity recorded 75, 80 µg urea.g.h-1 in the vegetable agriculture uses for Gzeria and Zngora soils alternately. Two bacterial isolates P. fluorescens GV2, Sp. urea ZV2 have achieved the best urease activity 8.40 ,7.99 mg.NH3 Lˉ1.hˉ1, Results have shown that the best activity of urea hydrolysis and Urease producing bacteria P. fluorescens GV2 and B.subtilisZB4 8.45 ,8.32 mg.NH3 Lˉ1.hˉ1 were at 38c˚ temperatures alternately. The isolates activity rate increased with increasing the urea concentration in the medium from 300to 900 mg urea Lˉ1. The highest rate was 62 mg NH3 Lˉ1. hˉ1 with 900 mg urea.Lˉ1 concentration by Sp. ureae ZV2. While the results have shown a decrease in the activity of isolates in hydrolyseis urea when using increased amounts of gypsum after 5%, the hydrolyze rate was 0.0 NH3 Lˉ1.hˉ1 for the B.subtilisZB4 at 10% gypsum and gradually decreased with increasing the amount of gypsum in the medium to reach 0.0 mg.NH3 Lˉ1.hˉ1 when using 15% of gypsum with Ur. pasteuri ZW4.