臺灣北部沿岸海水中甲醛降解微生物的分離和特性研究

Abstract

甲醛 ( formaldehyde ) 是一種廣泛應用於醫療、農業、工業的化學物，因其可破壞蛋白質和核酸，故具有生物毒性。本研究於台灣北部沿岸 5 個地點採集海水樣本，進行甲醛耐受微生物的培養、計數和分離，並測試分離株是否具甲醛降解能力以及研究其降解效率。結果發現，各樣水中甲醛耐受微生物的菌數均大於 240 cells / ml。根據 16S rRNA gene 及 26S rRNA gene 的定序及比對，顯示 8 株可耐受 25 ppm 甲醛的分離株中，4 株為真菌，分別為 Galactomyces 屬（1 株）及 Candida 屬（3 株），另外 4 株為細菌，分別為 Enterobacter 屬（1 株）、 Pseudomonas 屬（1 株）及 Bacillus 屬（2 株）。所有菌株皆無法以甲醇作為單一碳源生長。除 2 株 Bacillus 屬細菌，其餘 6 株分離株具有較強的甲醛耐受能力，以之進行甲醛降解測試，當菌液起始濃度為 0.2 ( OD600 ) 時，可在 PY broth 中於 72 小時內分解 54 % 至 98 % 100 ppm 甲醛，而細菌分離株 B3 在 PY broth 中可於 48小時內分解 100 % 400 ppm 甲醛，於 72 小時內分解 59 % 700 ppm 甲醛，提升 B3 的菌液起始濃度成 0.55 至 0.6 ( OD600 ) 並以搖瓶方式培養，其於 24 小時內即可分解約 97 % 1500 ppm 或 60 % 3200 ppm 甲醛。綜合分子親緣分析及生理生化特性測試結果，推斷 B3 屬 Enterobacter cloacae。分離株 B3 於未來或可應用於處理甲醛廢水。

Formaldehyde is a widely used chemical in medicine, agriculture and different industrial areas. It is biologically toxic because of its proteins and nucleic acid denaturing properties. Coastal seawater samples were collected from 5 regions of northern Taiwan. Microorganisms were cultured, counted and isolated for studies of formaldehyde degradation ability and degradation efficiency. Eight formaldehyde-tolerant bacterial and fungal strains were isolated. All strains can tolerate up to 25 ppm formaldehyde, but cannot grow on methanol as a sole carbon source. The formaldehyde-tolerant microorganisms were found in all water samples with concentrations greater than 240 cells / ml. The fungal isolates were classified to the genus Galactomyces ( 1 strain ) or Candida ( 3 strains ).The bacterial isolates were classified to the genus Enterobacter ( 1 strain ), Pseudomonas ( 1 strain ) or Bacillus ( 2 strains ). Isolates ( except 2 strains of Bacillus ) were used for formaldehyde biodegrading study, 54 % ~ 98 % of 100 ppm formaldehyde were degraded by these strains over 72 hours when the culture’s initial optical density at 600 nm was 0.2. 100 % of 400 ppm or 59 % of 700 ppm formaldehyde in PY broth were degraded by strain B3 in 48 or 72 hours. Strain B3 could also degrade 97 % of 1500 ppm or 60 % 3200 ppm formaldehyde in PY broth over 24 hours when the culture’s initial optical density at 600 nm was 0.55 ~ 0.6, and incubated with shaking. 16S rRNA gene sequence and phenotype analysis indicated that strain B3 was Enterobacter cloacae. Strains B3 may be useful for treatment of waste water containing formaldehyde.