自然环境中甲醛降解菌的分离筛选与鉴定

Isolation,screening and identification of a formaldehydedegrading strain in natural environment

[目的]筛选出具有甲醛降解能力的微生物,为甲醛降解菌的产业化利用提供技术支撑.[方法]采用PDA固体培养基分离甲醛耐受菌,在PDA培养基上培养观察耐受菌的形态特征,显微观察其孢子结构;采用rDNA-ITS基因序列同源性分析对目标菌株进行分子鉴定;通过测菌丝湿重来绘制其生长曲线,采用蛋白显色法测定甲醛浓度的变化.[结果]分离纯化出1株甲醛耐受真菌J-5,其培养特征、显微特征与曲霉属（Aspergillus）相似;18S rDNA核酸序列同源性分析发现,菌株J-5与曲霉属的6个株系为同一类群,所处类群中18S rDNA基因序列两两之间的相似值均在76％以上.J-5菌株最大可耐受甲醛浓度为2000 mg/L,可在192 h内将浓度为1560 mg/L的甲醛降解到100 mg/L以下.J-5菌株在培养0～96h内生长缓慢,但甲醛浓度下降迅速,当甲醛浓度下降到400 mg/L后,菌株生长迅速,甲醛浓度下降缓慢.[结论]分离筛选出1株甲醛降解菌J-5,经形态特征和分子生物学鉴定为曲霉属真菌,其在生长调整期对甲醛的降解速度最快.

[Objective]The formaldehyde degradation microbes were separated to provide theoretical basis and technical assistance for industrial utilization of formaldehyde degradation bacteria. [ Method ] Using the PDA solid medium to screen the formaldehyde degradation bacteria, the morphological characteristics and spore structures of formaldehyde degradation bacterial were identified by microscopic examination. Molecular identification of the targeted strains was conducted using rDNA-ITS sequence homology analysis. The wet weight of mycelia was measured for drawing the growth curve of strains and the formaldehyde concentration was determined by protein colorimetric method. [Result]One fungus of J-5 with good formaldehyde tolerance was separated, and its cultivation characteristics and microscopic characteristics were similar to Aspergillus. After comparison of the 18s rDNA sequence of J-5 strains with other 6 Aspergillus species, the similarity vai[ue of J-5 with other 6 strains was more than 76%. The maximum toler- able formaldehyde concentration of J-5 strain was 2000 mg/L, and it could degrade the formaldehyde from 1560 mg/L to lower than 100 mg/L within 192 hours. From Oh to 96 h, the J-5 strain grew slowly but the formaldehyde concen- tration decreased quickly. When the formaldehyde concentration was lower than 400 rng/L, the strains grew fast and the formaldehyde concentration declined slowly. [Conclusion]After morphological and molecular identification, it was found that the separated formaldehyde degradation bacterium J-5 belonged to Aspergillus, and the formaldehyde- degradation rate was the highest at the adjustment period of J-5 growth.