琼胶酶高产细菌的分离及鉴定

Isolation and identification of agarase-producing marine bacteria

从热带海洋中分离出能高效降解琼胶的菌株,并对其分类地位进行鉴定.在改良培养基上分离纯化出以琼胶作为碳源的能高效降解琼胶的细菌,以细菌基因组DNA为模板,设计合成细菌16SrDNA的通用引物,利用PCR技术对16SrDNA目的片段进行克隆,目的片段经过连接、转化和序列测定,测序结果与GenBank数据库收录的16SrDNAs序列进行BLAST比较分析,利用MEGA软件构建系统发育树,确定细菌的分类地位.分离鉴定的三株细菌,分别编号为FG1、FG2和FG3,均为革兰氏阴性菌,其16SrDNAs序列在GenBank中的收录号依次为JX073661、JX073662和JX073663.FG1菌株的16SrDNA与聚团拉布伦茨氏菌(Labrenzia aggregata)16SrDNA序列同源性达到99%;FG2与哈维氏弧菌(Vibrio harveyi)序列同源性达到99%;FG3与星箭头菌(Sagittula stellata)序列同源性达到97%.初步鉴定FG1与FG3均属于红细菌科(Rhodobacteraceae),FG1为拉布伦茨氏菌属(Labrenziasp),FG2为弧菌属(Vibrio sp),FG3为箭头菌属(Sagittulasp).

In order to isolate and classify agar-degrading bacteria with significant agarase activity,agar-degrading bacteria are isolated from the topical marine environment of South China by spread plate method、streak plate method.After purification,to investigate the phylogenetic position of the strains with significant agar-degrading activity,the 16S rDNAs sequences are cloned,sequenced and compared with those of related strains registered into the NCBI database.In order to determine their phylogenetic positions in bacteria king,MEGA software is used to build neighbour joining tree according to 16S rDNA sequences.Agar is used as the sole carbon source respectively in the improved medium to isolate and purify polysaccharide-degrading bacteria.16S rDNA universal primers of bacteria are designed and synthesized based on the bacterial genomic DNA.16S rDNAs sequences are cloned,sequenced and compared with those of related strains registered into the NCBI database.FG1 has 99% homology to Labrenzia agregata;FG2 has 99% homology to Vibrio harveyi;FG3 has 97% homology to sagittula stellata.Both of strains FG1 and FG3 are attributed to be Rhodobacteraceae.FG1 is attributed to be Labrenzia sp;FG2 is attributed to be Vibrio sp;FG3 is attributed to be Sagittula sp.