【摘要】 【目的】在基因水平上分析并比较陆地来源与海洋来源的放线菌产生卤化代谢产物的潜力。【方法】基于依赖黄素腺嘌呤二核苷酸的卤化酶基因筛选,从经过表型去重复的70株陆地来源和71株海洋来源的放线菌中,通过PCR筛选获得卤化酶基因片段,并进行测序鉴定;通过卤化酶氨基酸序列的系统发育分析,比较不同来源放线菌的卤化酶序列,以及海洋链霉菌和小单孢菌的卤化酶序列。另外,对卤化酶阳性菌株进行了聚酮合酶和非核糖体多肽合成酶基因的检测。【结果】本研究中36.6%的海洋放线菌具有卤化酶基因,其阳性率远高于本研究所涉及的陆地放线菌(14.3%);其中海洋链霉菌的卤化酶基因阳性率高达69.0%,而海洋小单孢菌的卤化酶阳性率仅为14.3%。86.1%的卤化酶阳性菌株具有聚酮合酶和/或非核糖体多肽合成酶基因。本研究获得的海洋来源的卤化酶序列与已知的卤化酶序列存在明显差异,在进化树上形成几个新的分支;其中链霉菌间的卤化酶序列相似性较高,而小单孢菌间的卤化酶序列差异较大。【结论】海洋来源的放线菌,尤其是海洋链霉菌,可作为未来获得新卤化活性物质的一类重要微生物资源。更多还原

【Abstract】 [Objective] To compare the halometabolite producing capability between actinomycetes of earth origin and marine origin,based on genetic screening of the 1,5-dihydroflavin adenine dinucleotide（FADH₂-dependent） halogenase gene.[Methods] We used 141 actinomycete isolates that were dereplicated by phenotype,70 of earth origin and 71 of marine origin,and obtained halogenase gene fragments from them by PCR screening.We then sequenced the PCR products and analyzed corresponding amino acid sequences phylogenetically.We made further comparison of the halogenase sequences between actinomycetes of different origins,and between marine-origin streptomycetes and marine-origin Micromonospora isolates.In addition,we detected polyketide synthase（PKS） and non-ribosomal peptide synthetase（NRPS） genes by PCR in the halogenase gene-positive isolates.[Results] We observed higher occurrence of the halogenase gene in marine-origin actinomycetes（36.6%） than in earth-origin actinomycetes（14.3%）,and in marine-origin streptomycetes（69.0%） than in marine-origin Micromonospora isolates（14.3%）.Most（86.1%） of the halogenase gene-positive isolates contained PKS and/or NRPS genes.Moreover,the halogenase sequences of marine-origin isolates differed largely from the known ones,and clustered into a couple of distinct clades in the phylogenetic tree.In addition,we found greater diversity of the halogenase genes in marine-origin Micromonospora isolates than in marine-origin streptomycetes.[Conclusion] Based on the results of this study,we propose that actinomycetes,especially streptomycetes,from marine habitat could serve as a good source for new bioactive halometabolite discovery in the future.更多还原