The diversity and habitat of sulphur-oxidizing bacteria recently gained the attention to consummate sulphur deficiency and to improve the fertility of soil. The present study strives to decrypt the abundance and diversity of sulphur-oxidizing bacteria in agricultural soil of Indore, Madhya Pradesh. A total of 40 different bacterial morphotypes were isolated from soil samples. Total of 14 isolates is screened on the basis of their efficacy to reduce pH of growth medium to 5 or less. The maximum pH reduction on starkey and thiosulphate broth is 4.37 and 4.41 by IS₂9GA, S12ND respectively. The maximum sulphate ion production was studied is IS₂10B (8.53mM), IS₂2B (7.25mM), IS₂9GA (7.14mM) and IS10NB (5.92mM), lowest by KA03B (0.782mM). Seven isolates showed mixotrophic growth utilize both elemental sulphur and thiosulphate as energy source; whereas 5 isolates utilized thiosulphate only and two utilize elemental sulphur only. These findings unveil the abundance of the SOB in agricultural soil and their role in the oxidation of sulphur.

Key Words: Oxidation, Sulphur-Oxidizing Bacteria (SOB), Sulphur, Sulphate ion, Thiosulphate.