Abstract

                                Beggiatoa, an organism capable of oxidizing hydrogen sulfide has been isolated from rhizosphere of rice grown under submerged ecosystem. The isolation procedure involves prior enrichment with extracted hay and soil extract under various treatments viz., addition of acetate or sodium sulfide or acetate + sodium sulfide, diluted and undiluted soil extract. The results indicated that diluted (1:1) soil extract with sodium sulfide enrichment had registered higher number of 22.5 trichomes ml', followed by acetate + sodium sulfide treatment, apart from reducing the bacterial and protozoan contaminants to a minimal level. Formation of puff balls and mat in the sub-surface of the enrichment medium suggest that they are microaerophilic and grown in the interface between oxygen and hydrogen sulfide environments. Growth of Beggiatoa was also observed in Beggiatoa medium 2 as circuitance type of colony. Morphological characterizations of this isolate showed its close resemblances with that of B. alba

Key words : Beggiatoa, Enrichment, Isolation, Rice rhizosphere