【摘要】 采用未培养(Culture independent)技术直接从荷斯坦奶牛瘤胃液中提取瘤胃细菌微生物混合DNA(也叫元基因组DNA),利用细菌16SrDNA通用引物27F与1492R,扩增瘤胃混合微生物的16SrDNA,根据16SrDNA序列对瘤胃细菌多样性进行初步分析。通过16SrDNA序列同源性分析,发现有多于一半以上的序列与可培养的菌株的同源性小于90%,属于不可培养的菌株。选用45条测得序列与已知序列构建系统发育树,分析结果表明,它们分属于两大类LGCGPB(the lowG+CGram positivebac teria)和CFB(Cytophaga_Flexibacter $CBacteroides group),剩下的克隆尚难确定其分类地位,可能是代表新属和种的序列,这些序列已向GenBank提交并得到序列号(AY986777_AY986791)。更多还原

【Abstract】 Culture independent method was used to study the diversity of rumen bacteria. Molecular diversity of rumen bacteria was analyzed by PCR amplification and sequencing of 16S rDNA clone libraries prepared from the rumen content of Holstein cows. The total DNA directly extracted from rumen fluid was used as PCR template. Bacteria universal primer 27F and 1492R was used as primer. Random clones, containing almost full size 16S rDNA sequences (about 1.5 kb long), were sequenced and subjected to an on line similarity search. The 16S rDNA sequence analysis indicated that more than half of the sequences belonged to the not-yet-cultured groups. The 16S rDNA similarity levels with cultured species was less than 90%. The bacterial community structure was also revealed by phylogenetic tree of known sequences and selected sequence. In the library from the rumen fluid, the sequences were mainly affiliated with the following major phyla: low G+C Gram-positive bacteria, Cytophaga-Flexibacter-Bacteroides, and the remaining sequences were placed within not-yet-uncultured groups that had an uncertain affiliation. These several sequences are likely to represent novel taxonomic groupings. The nucleotide sequences have been submitted to the GenBank/EMBL /DDBJ databases under accession numbers AY986777-AY986791.更多还原