Evaluation of Four Pea (Pisum sativum) Cultivars in PE-2 Medium for the MPN Enumeration of Anaerobic Spore-Forming Organisms

Abstract

Untreated ‘Alaska’ seed peas have traditionally been used to prepare PE-2 medium, a medium used to recover anaerobic bacteria. Three cultivars of seed peas, ‘Columbian’, ‘Yellow’, and ‘Scotch’ were compared to the cultivar ‘Alaska’ peas in PE-2 for recovery of Clostridium butyricum ATCC 860, Clostridium sporogenes ATCC 7955/NCA 3679, and Thermoanerobacterium thermosaccharolyticum ATCC 25773 determined by using the most probable number (MPN) technique. Organisms were grown in cooked meat medium (CMM) and enumerated by the three-tube MPN method in PE-2 media incubated at 37°C for 48 h. Recovery of C. butyricum and T. thermosaccharolyticum grown in homogenates of commercial cream-style corn and vegetable beef soup were also evaluated. Similar recovery of organisms from stock cultures or from foodstuffs were observed in PE-2 prepared with three of the pea cultivars (‘Alaska’, ‘Columbian’, and ‘Yellow’). While the ‘Scotch’ cultivar PE-2 medium yielded recoveries comparable to PE-2 prepared with the other pea cultivars, turbid tubes were occasionally observed from which viable microorganisms could not be recovered. This cultivar is therefore not recommended due to the probability of yielding false positives in the MPN technique.