An organism, which degrades alpha-picoline but also utilizes 2-ethylpyridine or piperidine as alternative growth substrates, has been isolated from soil and characterized as arthrobacter sp. alpha-picoline-grown cells oxidize 2-ethylpyridine and vice versa. Other pyridine derivatives tested are neither utilized as growth substrates nor oxidized by the organism. alpha-Picolinate and 2-hydroxy-6-methylpyridine are not metabolized, indicating that degradation is neither initiated by methyl oxidation nor by hydroxylation in the 6-position of pyridine ring. Succinate semi-aldehyde and pyruvate accumulate when alpha-picoline oxidation by resting cell suspensions is blocked by semicarbazide. The Arthrobacter grown on alpha-picoline rapidly oxidizes succinate semi aldehyde...