EFFECT OF SULFUR AND ORGANIC MATTER LEVELS ON ABUNDANCE AND ACTIVITY OF PHOTOAUTOTROPIC SULFUR AND THIOSULFATE BACTERIA IN SOIL UNDER DIFFERENT INCUBATION TIME

Abstract

The study was conducted to specify the effect of three levels 0, 1, 2 S/Kg soil (S0, S1, S2)respectively of agricultural sulfur and two types of organic substance (Manures) without adding CO and the dry powder of alfalfa C1 and manures C2, added within the average of 6 grams C/Kg soil on the presence and activity of minute photo autotrophic sulfur oxidation by an experience conducted under laboratory conditions by utilizing silty soil achived under factorial experiments of CRD design. All samples were incubated at 280 C for different periods 15, 30, 45 days (T1, T2, T3) respectively. Activity and diversity of bacteria related to types Thiobacillus of T. thioparus was estimated through measuring the quantity of thiosulphate oxidation and the differences of values related pH at the media specified for this bacteria. The results showed that increasing the addition of agricultural sulfur has a great effect (P<0.05) on increasing the density and activity of photo-autotrophic sulfur oxidizing bacteria its number is 0.98*102 cfu/g and 1.31*102 cfu/g when adding alfaalfa and cow manures respectively compared with 1.96*102 cfu/g on the control treatment. Differences in incubation periods showed that 30 days is the highest level of density 0.73*102 cfu/g. Interferences among levels of sulfur, organic substance and incubation period showed that the highest level of (P<0.05) is 3.071*102 cfu/g with treatment S1-CO T3. It was obvious that the soil utilized in the study was containing oxidizing thiosulphate T. thioparus photo-autotrophic bacteria in wich its activity increased with the treatment S1-CO T3. The amount of oxidation of thiosulphate was 377 mg/100 ml, and the Ph at the media was 5.71. the soil utilized was void of sulfur oxidizing bacteria.