Effect of biocides to odor-producing microorganisms in the hydrophilic coating

The metabolic activity of microorganisms is considered one of the reasons why evaporators of the automobile and household air conditioning systems produce the malodor. The odor-causing by microorganisms can be reduced by incorporating biocide in the hydrophilic coating. The objective of this work was to understand the mechanisms how the microorganisms produced the odor and to analyze the chemical compound of the odor. Experiments were conducted to measure the variation of odor and to assess the antimicrobial property of epoxy resin-based hydrophilic coatings of evaporators. Then the microorganisms used the experiments were as followed; four bacteria cultured from an evaporator of household air conditioning system were metylobacterium phylloshaerae, metylobacterium radiotolerans, sphingomonas aquatilis, and bacillus subtilis, and three molds were aspergillus niger (ATCC 6275), paecilomyces variotii (ATCC 18502), and trichoderma viren (ATCC 9645). Then the four bacteria and three fungi mixed with similar concentration respectively and were recoverable repeatedly for seven days. The change of intensity and types of odor-causing chemicals as a result of their metabolic activity were measured by Gas chromatography-mass spectrometry (GC-MS) measuring and sensory evaluation of odor. In order to compare the number of microorganisms, the samples were incubated for two days at 35°C and R2A agar was employed for the isolation of bacteria and fungi.