ISOLATION OF DEXTRAN PRODUCING MICROORGANISMS FROM MITR PHUVEING SUGAR FACTORY AND THE EFFECT OF DIMETHYL BENZYL AMMONIUM CHLORIDE

摘要

Aims: Microorganisms producing dextran during the milling process. Investigations were also undertaken to examine the effect of DBAC against the dextran producing bacteria. Dextran is a polysaccharide consisting of glucose monomers linked mainly by a(1-6) bonds, produced by numerous microorganisms. It is well known that dextran in cane detrimentally affects processing in the sugar industry. Many microorganisms have been isolated from sugarcane juice during the milling process at Mitr Phuveing SugarFactory. Methods & Results: These organisms were screened for their dextran producing property by selecting mucoid colonies on plate count agar (PCA), MRS agar and malt extract (ME) agar medium containing 10% sucrose. The secondary and tertiary screeningwas accomplished by growing them in sugarcane juice and complete liquid medium (CM) adding 10% sucrose, aerobically at the appropriate temperature for each isolate. The rapidly growing strains were selected. The bacterial strains were Klebsiella pneumoniae, Enterobacter cloacae, and Lactobacillus fermentum. Among these, K. pneumoniae P100 produced the maximum concentration of dextran of 6,800 ppm at stationary phase within 12 hours of incubation in CM. The activity of the biocide, 2 ppm of Dimethyl Benzyl Ammonium Chloride (DBAC) used to inhibit some microorganisms in the modern cane milling process at Mitr Phuveing Sugar Factory, could not inhibit K. pneumonia P100 within 30 minutes. Significance of Study: From these experiments, the factory has changed the sanitization during the milling process, which has saved on biocide costs.