Simplified and Rapid Enumeration of Proteolytic Bacteria in Water Using the Plate-MPN Technique

Abstract

The plate-MPN technique, a simplified system for calculating of viable bacteria that combines both the surface-plate method and the most probable number (MPN) method, has been successfully applied to the determination of numbers of proteolytic bacteria in natural water. The analysis of 13 fresh-water and 10 seawater samples revealed that the plate-MPN technique had same performance relative to the conventional method required the colony isolation and screening for the proteolytic activity test. Proteolytic bacteria of 1.3 × 10 - 7.9 × 10³ were detected by the plate-MPN technique for 12h incubation, while the conventional method spends for 3 days until similar results could be drawn. A high correlative relationship (r=0.990, n=23) was observed between the counts by the plate-MPN technique and the conventional method, strongly indicating that the plate-MPN technique can be recommended method for rapid enumeration of proteolytic bacteria.