报告人：刘如龙博士（香港科技大学理学院海洋环境科学专业）
报告题目：DIVERSITY, DISTRIBUTION AND POPULATION DYNAMICS OF FECAL BACTEROIDALES COMMUNITIES IN THE MARINE ENVIRONMENT OF HONG KONG: IMPLICATIONS TO WATER QUALITY MONITORING

报告时间：4月27日（周一）上午10:30-12:00
报告地点：理学院报告厅（理科楼352）
 

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ABSTRACT

Fecal pollution of water environment poses serious threats to public health. Because each species of animal host carries a different variety of fecal pathogens, the identification of pollution sources (i.e. animal species) is the key to accurate health risk assessment and effective implementation of mitigation measures. Since a decade ago, Bacteroidales have emerged as a promising bacterial indicator for fecal pollution source identification (source tracking). However, existing knowledge on Bacteroidales has been mainly acquired from temperate zones; due to possible variations in the diversity and environmental fate of Bacteroidales in different climate zones, the applicability of the bacteria to source-tracking in the warmer regions of the world is not known. This study investigated for the first time the diversity, distribution and population dynamics of Bacteroidalescommunity in the feces of warm-blooded animals and in the coastal seawaters of a tropical / subtropical region (Hong Kong). The analysis of the 16S rRNA genes retrieved from the feces of different species of warm-blooded animals in Hong Kong revealed a large number of novel sequences, indicating that the diversity of Bacteroidales in warmer regions of the world is different from that in the temperate zone. A highly host-specific distribution of Bacteroidales lineages was observed among the eight species of warm-blooded animals investigated in the study. These lineages were found in and only in seawater samples collected from coastal regions that are known to be polluted by the feces of the corresponding host types (e.g. effluent of pig farms, household sewage, and terrestrial runoff from grazed pastures). Novel genetic markers were identified for the host-specific lineages; those markers demonstrated highly specific and sensitive source identification for field samples. Bacteroidales cells showed rapid decay in subtropical Hong Kong seawaters. Although Bacteroidales are obligate anaerobes, a high level of dissolved oxygen alone in seawater did not affect the decay of Bacteroidales communities, but it effectively accelerated the decay rate when interacting with light. The results indicate a significant effect of photo-oxidation on the decay of Bacteroidales in natural environment. Close correlations were observed between the decay of Bacteroidales and other fecal microorganisms (i.e. E. coli), demonstrating the potential of using the bacteria in indicating the health risks. The findings in this study greatly enrich the knowledge of biology and ecology of fecal Bacteroidales and support the application ofBacteroidales in fecal pollution source tracking in the warm regions of the world.

理学院

2015年4月24日

附：报告人简介

刘如龙，香港科技大学理学院海洋环境科学专业博士（2008-2012），香港科技大学环境工程学院博士后（2013至今），长期从事环境微生物学特别是微生物生态学研究，对海洋环境，污水及污水处理系统等几种相互联系、相互影响的环境体系中细菌群落结构及功能随环境因素的变化有较为深入的研究，建立了较强的交叉学科背景。并且以生态学研究为基础，致力于开发海洋水质监测新技术。他的主要研究贡献有：1）揭示了海洋好养不产氧光和异养细菌（aapb）在太平洋表层水体的分布；2）揭示了aapb细菌在热带珊瑚礁区域的碳循环中的贡献，并首次利用分裂细胞频率计算了aapb细菌生产力的方法 ； 3）研究了污水微生物（粪源微生物）的细菌生态学及其排放对海洋环境中微生物群落结构的潜在影响，并且研发了拟杆菌的分子标记物用于海水中粪源微生物污染的朔源（鉴别污染来自何种动物）；4）利用分子生物学手段，成功鉴定出一种新型聚磷菌具有在硫循环介导下从污水中同时去除碳，氮和磷等营养盐的潜能 。这一发现若在后续研究中证实，则可能预示着生物地球化学循环中一种新型代谢途径。目前他已经在Environmental Microbiology, Water Research, Applied Microbiology & Biotechnology等国际高水平学术杂志发表学术论文7篇（4篇为第一作者），其中JCR一区一篇，JCR二区五篇。