Various microorganisms are capable of breaking down tobacco alkaloids by different biochemical processes and possess characteristic enzymatic systems for the catabolism of nicotine. Bacteria of the genus Pseudomonas and the fungus Cunninghamellaechinulata degrade nicotine via N-methylmyosmine and pseudooxynicotine which is linked to the opening of the pyrrolidine ring (pyrrolidine pathway), whereas Arthrobacteroxidanshydroxylates the pyridine ring in the 6-position. 6-hydroxynicotine is produced as a primary product (pyridine pathway). Tobacco plants, and some fungi (e.g. Pelliculariafilamentosa) degrade nicotine via demethylation to nornicotine (methyl pathway). As a result of the microbial degradation of nicotine and other tobacco alkaloids, carbon and nitrogen are made bioavailable. Following metabolic conversion to carboxylic acids, the reaction products are used by unicellular organisms as primary nutrients and a source of energy for the synthesis of new cell compounds.