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石内真菌:恐龙大绝灭的可能杀手
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作者 龚一鸣 徐冉 胡斌 《中国科学(D辑)》 CSCD 北大核心 2008年第4期439-444,共6页
湖北省丹江口市温家坪剖面晚白垩世晚期胡岗组上部紫红色砂质泥岩中含丰富的恐龙蛋壳碎片.运用环境扫描电子显微镜,在保存良好的恐龙蛋壳柱状层中发现了大量的石内真菌.这些石内真菌以不同的角度钻掘寄主,并有选择地富集在恐龙蛋壳... 湖北省丹江口市温家坪剖面晚白垩世晚期胡岗组上部紫红色砂质泥岩中含丰富的恐龙蛋壳碎片.运用环境扫描电子显微镜,在保存良好的恐龙蛋壳柱状层中发现了大量的石内真菌.这些石内真菌以不同的角度钻掘寄主,并有选择地富集在恐龙蛋壳柱状层差的生物结晶带内.单个石内真菌呈针状、带状、丝状,长5~18μm,基部宽0.3~0.5μm,不分叉.石内真菌与寄主有相同的石化特征、脆性断口、质地和主要化学成分.石内真菌的主要成分为氧、碳和钙,次要成分为钠、钾、氯和硫.认为石内真菌入侵恐龙蛋的时间发生在恐龙蛋形成后和石化作用前,白垩纪末期石内真菌入侵恐龙蛋,致使其不能正常孵化和夭折可能是导致恐龙大绝灭的直接原因. 展开更多
关键词 石内真菌 恐龙蛋 白垩纪 大绝灭
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Antimicrobial Activity of Ulva reticulata and Its Endophytes 被引量:3
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作者 Dhanya K.I. Swati V.I. +1 位作者 Vanka Kanth Swaroop Osborne W.J. 《Journal of Ocean University of China》 SCIE CAS 2016年第2期363-369,共7页
Seaweeds are known to exhibit various antimicrobial properties, since it harbours an enormous range of indigenous bioactive compounds. The emergence of drug resistant strains has directed to the identification of pros... Seaweeds are known to exhibit various antimicrobial properties, since it harbours an enormous range of indigenous bioactive compounds. The emergence of drug resistant strains has directed to the identification of prospective metabolites from seaweed and its endophytes, thereby exploiting the properties in resisting bacterial diseases. The current study was aimed to assess the antimicrobial activity of extracts obtained from Ulva reticulate, for which metabolites of Ulva reticulata and its endophytes were extracted and assessed against human pathogens like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Bacillus subtilis. It was observed that the hexane extract of isolate VITDSJ2 was effective against all the tested pathogens but a significant inhibition was observed for Staphylococcus aureus and Escherichia coli. Further, Gas chromatography coupled with Mass spectroscopy (GC-MS) revealed the existence of phenol, 3, 5-bis (1, 1-dimethylethyl) in the crude hexane extract which is well-known to possess antibacterial activity. The effective isolate VITDSJ2 was identified to be the closest neighbour of Pseudomonas smtzeri by phenotypic and genotypic methods. The crude extracts of the seaweed Ulva reticulata was also screened for antibacterial activity and the hexane extract was effective in showing inhibition against all the tested pathogens. The compound in the crude extract of Ulva reticulata was identified as hentriacontane using GC-MS. The extracts obtained from dichloromethane did not show significant activity in comparison with the hexane extracts. Hence the metabolites of Ulva reticulata and the bacterial secondary metabolites of the endophytes could be used in the treatment of bacterial infections. 展开更多
关键词 endophytic bacteria ANTI-MICROBIAL MACROALGAE bioactive compounds GC-MS
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