摘要
豨莶草有多种药用价值,旨在从豨莶草果实中分离和筛选出高拮抗活性的内生细菌。采用了形态学观察、生理生化试验、16S r RNA序列比对、系统发育树分析以及OD600值、药敏试验和超滤等方法对该抗感染细菌C-5-1进行了相关生物学特性评价。结果显示,C-5-1为侧孢短芽孢杆菌(Brevibacillus laterosporus),对多种病原细菌均敏感,尤其是对铜绿假单胞菌;低p H和高Na Cl盐度环境中耐受性有限,在p H≤5.0或盐度≥15%时其生长受到了完全的抑制甚至是死亡,但在p H范围7.0-11.0和盐度范围0-5%下均能生长良好,说明该菌株为耐碱,但不耐酸和盐;筛选出了对菌株C-5-1高度敏感而对5种指示病原菌耐药的抗生素,即氨苄西林;C-5-1发酵上清液中存在着两种抗菌物质,且它们的相对分子质量均小于2 000。因此豨莶草有着优良微生物资源,可以成为开发抗感染细菌药物的重要资源。
Herba siegesbeckiae has many healing values,and our aim is to isolate and screen highly active antagonistic endophytesfrom its fruits. The biological characteristics of anti-infective bacterium C-5-1 were determined by antagonistic experiment,morphologicalobservation,physiological and biochemical tests,sequence alignment of 16 S r RNA gene,analysis of phylogenetic tree,measuring OD600,drug sensitive tests,and ultra-filtration centrifugation. The results showed that the C-5-1 was identified as Brevibacillus laterosporus and wassensitive to various pathogenic bacteria,especially Pseudomonas aeruginosa. The strain C-5-1 had limited tolerance to low p H and highlysaline environments,i.e.,inhibited completely or even died in p H≤5 or more than 15% Na Cl,but it grew well in p H≥7 and 0-5% Na Cl,suggesting that C-5-1 had good alkali resistance,but not resistant to acid and salt. Screening experiment revealed that the antibiotic ampicillinwas highly sensitive to C-5-1,but resistant to 5 pathogenic bacteria. Fermentation supernatant of C-5-1 contained two antibacterial substancesand relative molecular mass of both was less than 2 000. Conclusively,H. siegesbeckiae having excellent microbial resources will be a keyresource for the development of anti-bacteria drugs.
引文
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