| Summary: | 碩士 === 國立臺灣大學 === 森林學研究所 === 91 === To evaluate the biocide effect of quaternary ammonium chloride (QAC), a whitewater sample was taken from a fine papermachine headbox. By dilution spreading plate method, 51 strains of aerobe and facultative anaerobe were isolated morphologically. Then the strains were separately transfered to basal medium and were incubated before the beginning of log phase. To identify strains with different QAC resistance, 30-120 ppm of N-Alkyl-benzyl-dimethyl ammonium chloride were added to basal medium. Biocide effect was investigated by comparison of bacterial growth, which could be monitored by 600 nm light absorbance of basal medium suspension. Among all strains, 22 strains could survive up to 30 ppm of QAC, 60 strains could survive up to 60 ppm of QAC, 6 strains could survive up to 90 ppm of QAC, 2 strains can survive up to 120 ppm of QAC. API20E and 16S rRNA gene sequencing technique were applied to identify two strains with highest QAC resistance.
One strain (HB22) was identified as Morganella morganii. The other (HB45) was identified with high similarity among Pseudomonas cf. monteili or Pseudomonas mosselii or Pseudomonas putida. HB22 is Gram-negative rod, motile with flagella, catalase positive, oxidase negative, Indole positive, H2S production negative, facultative anaerobe. HB22 has optimum growth condition of 35oC and pH 7.0. HB45 is Gram-negative rod, motile with flagella, catalase positive, oxidase negative, Indole negative, H2S production negative, aerobe. HB45 has optimum growth condition of 30oC and pH 7.4.
HB22 could resist QAC concentration up to 150 ppm and inhibitory time was 5-10 hrs at 35℃-40℃. HB22 could catabolize only glucose and D(+)-Mannose. HB45 could resist QAC concentration up to 200 ppm and inhibitory time was 6-10 hrs at 30℃-35℃. HB45 could catabolize L-Arabinose, L(+)-Rhamnose, D(+)-Mannose, Glucose, Glycerol, Lactose, Maltose, Raffinose, Xylose, Cellulose and Xylan.
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