Having in mind, achievement of self sufficiency in sugar, the land under cultivation of sugarcane, and as a result the use of chemical nitrogen fertilizer in Khuzestan province has been increased causing a pollution problem. Gluconacetobacter diazotrophicus is an associative endophyte nitrogen fixing bacteria in sugar cane which is entirely confined to the living plant tissue and does not survive in soil and therefore can only be isolated by tissue extraction. five native isolates along with 3 imported species were employed in this study. This bacteria produces orange to red colonies on solid standard LGIP medium. The colonies turn brown in an old culture. White colonies are produced in solid PDA medium. They can turn dark brown after 10 days. The bcterium produces brown colonies along with water soluble brown pigment in GYC medium. It grows in high glucose (30%) concentrations producing acetic acid. This bacteria can be identified by negative oxidase and nitrate reductase and by positive catalase tests. It produces acid by oxidizing ethanol, however it does not complete the second stage of oxidation. The capability of the bacteria for biological nitrogen fixation(207-253 nmoles C2H4
h-1ml-1 ) was evaluated through ARA method.
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