Determination of the concentration of maltose- and starch-like compounds in drinking water by growth measurements with a well-defined strain of a Flavobacterium species

Abstract

The growth kinetics of Flavobacterium sp. strain S12 specialized in the utilization of glycerol, and a number of oligo- and polysaccharides were determined in batch-culture experiments at 15°C in pasteurized tap water supplied with very low amounts of substrates. K(s)s for the growth on maltotriose, maltotetraose, maltopentaose, and maltohexaose were 0.03 μM or less and below those for glucose (1.5 μM) and maltose (0.16 μM). K(s)s for starch, amylose, and amylopectin were 8.4, 25.6, and 11.0 μg of C per liter, respectively. A yield of 2.3 x 107 CFU/μg of C on the oligo- and polysaccharides was calculated from the linear relationships observed between maximum colony counts in pasteurized tap water and the concentrations (usually below 25 μg of C per liter) of supplied compounds. The maximum colony counts of strain S12 grown in various types of raw water and tap water revealed that raw water contained only a few micrograms of maltose- and starch-like compounds per liter; in tap water the concentrations were all below 1 μg of C and usually below 0.1 μg of C per liter. The application of starch-based coagulant aids gave increased concentrations of maltose- and starch-like compounds in the water during treatment, but these concentrations were greatly reduced by coagulation and sedimentation, rapid sand filtration, and slow sand filtration.