萘降解菌N19-3的分离、鉴定和萘双加氧酶基因的检测

从石油污染土壤中分离到一株高效降解萘的N19-3菌株. 经形态观察、生理生化实验和16S rDNA序列分析等鉴定其为丛毛单胞菌属（Comamonas sp.）. 该菌株能在30 ℃，30h内将1 000mg/L的萘完全降解. 降解萘的适宜温度为20～30 ℃, 适宜pH为7.0～9.0. 0.1mmol/L的Ca2+和Fe3+对N19-3菌株降解萘有较强的促进作用, 0.1 mmol/L的Mn2+和Zn2+对N19-3菌株的生长和萘的降解也有一定的促进作用, 而0.1 mmol/L的 Cu2+则完全抑制了N19-3菌株的生长和萘的降解. 通过PCR方法在N19-3菌株中扩增出分别与C. testosteroni H菌株的萘双加氧酶铁硫蛋白大亚基基因（pahAc）与双加氧酶铁硫蛋白小亚基基因（pahAd）高度同源的核苷酸片断. 

Isolation and Characterization of Naphthalene-Degrading Bacteria Comamocas sp. N19-3 and Detection of Its Naphthalene-Dioxygenase Gene

A naphthalene-degrading bacterium （referred as N19-3） was isolated from the oil-contaminated soil. Based on morphological, physiological and biochemical characteristics and 16S rDNA sequences, N19-3 was identified as Comamocas sp.Strain N19-3 could degrade 1 000 mg/L naphthalene completely within 30hour at30 ℃.The optimum temperature and pH for growth and naphthalene degradationwere 20～30 ℃ and pH 7.0～9.0 respectively. The Ca2+, Fe3+ （0.1 mmol/L） could greatly enhance the growth of strain N19-3 and degradation of naphthalene. The Mn2+ and Zn2+ （0.1 mmol/L） also promoted the growth of strain N19-3 and degradationof naphthalene. But the Cu2+ （0.1 mmol/L） could absolutely inhibit the growth and degradation of naphthalene. Two genes were obtained which were highly homologous to pahAc and pahAd genes encoded the large and small subunit of naphthalene dioxygenase from C. testosteroni H by PCR.