en مقاله کامل Full Length/Original Article The biodegradation of secondary amines is particularly important due to their propensity for conversion either chemically or microbiologically to N-nitrosamines which are potent carcinogens. In this research, a weak Gram-positive organism was isolated from river and identified as Mycobacterium. This Mycobacterium grows slowly and effectively utilizes piperazine as the sole source of organic, carbon, nitrogen and energy. Also, it has one 60-kb plasmid on gel agarose which involves in piperazine degradation however the mutant strain which were obtained by subculturing in nutrient broth (pip-) has lost this plasmid. This might suggest that the ability to degrade piperazine are plasmid encoded. Mycobacterium, Plasmid, Piperazine 113 116 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-381&slc_lang=en&sid=1 Giti Emtiazi گیتی امتیازی emtiazi@sci.ui.ac.ir Yes Mohammad Reza Norri Daloii محمدرضا نوری دلویی No Mona Hosseini مونا حسینی No