红树林根际土壤中耐高盐苯酚降解菌的分离鉴定

Isolation and identification of halotolerant and phenol-degrading bacterial strains from rhizosphere soil of mangrove

苯酚对海洋生态环境具有较大的威胁,从红树林根际土壤中分离获得对环境具有高适应性的高效芳烃降解菌具有重要的意义。本研究对北部湾红树林根际土壤中的苯酚降解菌进行富集培养,经过分离纯化得到30株菌株,筛选得到5株菌株FGYS1、FGYS7、FGYS11、FGYB1和FGYB5,可耐受70 g/L NaCl的高盐环境,最高可降解1500 mg/L的苯酚。采用形态观察、BOX-PCR菌种多样性分析、16S rRNA序列分析等方法对菌株进行鉴定,均为假单胞菌属(Pseudomonas)。菌株FGYS1、FGYS7和FGYS11为同一种假单胞菌,与Pseudomonas extremaustralis 14-3 T和Pseudomonas meridiana CMS 38 T的16S rRNA序列相似性分别达到99.71%和99.64%。菌株FGYB1和FGYB5为同一种假单胞菌,分别与Pseudomonas veronii DSM 11331 T和Pseudomonas extremaustralis 14-3 T的16S rRNA序列相似性均达到99.64%。16S rRNA序列的系统发育树分析表明菌株FGYS1、FGYS7、FGYS11、FGYB1和FGYB5在进化上与P.veronii为同一个分支,而与假单胞菌属其他模式菌株的序列进化关系相距较远。菌株FGYS1降解苯酚的适宜温度为25~35℃、适宜pH为4~6、最高耐NaCl含量为60 g/L;菌株FGYB1降解苯酚的适宜温度为25~35℃、适宜pH为4~6、最高耐NaCl含量为100 g/L,两株菌株对pH、温度和盐度的适应范围较广。菌株FGYS1和FGYB1还可以同时降解邻苯二酚、对苯二酚和间苯二酚。本研究分离得到的苯酚降解菌在应对红树林芳烃污染和生态环境修复方面显示了较大的潜力。

Phenol is a great threat to marine ecological system,so it is of great significance to isolate phenol-degrading bacteria characterizing higher effectiveness and higher adaptation of marine environment.In present work,phenol-degrading bacteria were enriched and isolated from rhizosphere soil of mangrove around Beibu Gulf.A total of 30 strains were isolated and purified.As a result,five strains named FGYS1,FGYS7,FGYS11,FGYB1 and FGYB5 were obtained.It shows that they could tolerate 70 g/L high concentration of sodium chloride and degrade phenol up to 1500 mg/L.They were identified by morphological observation,BOX-PCR diversity analysis,16S rRNA and gyrB gene sequence analysis.All of them were Pseudomonas.FGYS1,FGYS7 and FGYS11 are consistent in 16S rRNA gene sequence.The nucleotide sequence similarity of 16S rRNA gene to those of Pseudomonas extremaustralis 14-3 T and Pseudomonas meridiana CMS 38 T in the EzBioCloud data base was 99.71%and 99.64%,respectively.It is the same for the strains FGYB1 and FGYB5,the similarity of 16S rRNA gene to those of Pseudomonas veronii DSM 11331 T and Pseudomonas extremaustralis 14-3 T was both 99.64%,respectively.The phylogenetic tree analysis of 16S rRNA gene showed that FGYS1,FGYS7,FGYS11,FGYB1 and FGYB5 located in the same branch with P.veronii,but relatively far away from other model strains of Pseudomonas.The suitable growth conditions for phenol degradation by strain FGYS1 were 25-35℃,pH 4-6 and the sodium chloride concentration less than 60 g/L.While for strain FGYB1,the conditions for phenol degradation were 25-35℃,pH 4-6,and the sodium chloride concentration less than 100 g/L.FGYS1 and FGYB1 could also degrade catechol,hydroquinone and resorcinol simultaneously.These phenol-degrading bacteria exhibited potential utilization in the disposition of aromatic pollution and the restoration of environment in mangrove ecosystem.