MIP: Symbionts and Signaling: Quorum Sensing Among Sponge-Associated Bacteria

海绵已被证明是抗癌药物和抗生素等新型药物的丰富来源。这些简单的动物还拥有大量但稳定的共生微生物种群，这些微生物往往是具有药用活性的化合物的来源。除了为宿主动物产生有用的代谢物外，这些微生物还可以发挥其他重要功能，包括获得有限的营养和保护免受有害病原体的侵害。海绵中的微生物群落复杂多样，代表了许多不同类型的微生物，具有广泛的能力。就像大多数复杂的微生物群落一样，人们几乎不了解海绵中建立和稳定微生物区系的因素和机制。对于海绵来说，面对周围大量含有微生物的海水，具体的微生物是如何引入和维持的，以及不同微生物如何在海绵组织中培养出适当的平衡，目前尚不清楚。细菌协调其活动的一种机制是通过交换化学信号。近年来，很明显，许多细菌可以通过不同的化学语言进行“对话”，这种微生物对话可以对微生物群落的功能产生重大影响。在NSF的一个相关微生物观测项目中，一大群与海绵相关的微生物被发现能产生一种名为酰基高丝氨酸内酯(AHLS)的特定通讯信号家族，已知调节其他细菌中的抗生素合成、营养获取和微生物基因交换等各种过程。AHL是塑造海绵群落和促进微生物活动协调的主要候选因素。这项研究将测试这些信号机制对几种浅水热带海绵中特征良好的微生物群落的渗透性和重要性。先进的化学、生化、分子、显微和微生物学分析将被应用于确定这些本土微生物在海绵内的交流程度、信号控制下的功能以及与海绵重要属性的联系，包括产生新的代谢物。这项研究将提供关于微生物群落在宿主联合期间繁殖和成熟的方式、促进共生而不是疾病的微生物活动的调节，以及这些微生物和海绵之间的功能关系的广泛见解。在更广泛的意义上，这项研究将促进对复杂的共生过程的理解，并有助于了解细菌与宿主之间相互作用中的信号传递。这个跨学科项目涉及三个具有不同专业领域的不同实验室，并将以连接化学、生态学和分子微生物学传统领域的方式培训研究生和博士后研究人员。本科生的参与也是这项研究的重要组成部分。除了本科生研究助理，该项目还包括支持继续成功的夏季微生物学和研究培训(SMART)课程，该课程为巴尔的摩海洋生物技术中心的少数族裔学生提供为期两周的强化实验室研究体验。本课程与研究科学家、博士后研究人员和研究生密切合作，为学生提供关注海绵微生物群落的现实研究体验。

Marine sponges have proven to be a rich source for novel pharmaceuticals such as anticancer drugs and antibiotics. These simple animals also harbor a vast, yet stable population of symbiotic microorganisms that are often the source for the medicinally active compounds. In addition to generating useful metabolites for the host animal these microbes can also perform other important functions, including acquisition of limiting nutrients and protection against harmful disease agents. The microbial communitieswithin sponges are complex and diverse, representing many different types of microbes with a great range of capabilities. As with most complex microbial communities, there is virtually no understanding of the factors and mechanisms that establish and stabilize the microbiota in sponges. For marine sponges, it is unclear how specific microbes are introduced and maintained in the face of the huge volume of microbe-containing seawater surrounding them, and how the appropriate balance of different microbes is fostered within the sponge tissue. One mechanism by which bacteria coordinate their activities is through the exchange of chemical signals. Over recent years it has become clear that many bacteria can "converse" through different chemical languages, and that this microbial conversation can have a major impact on microbial community function. In a related NSF Microbial Observatory project, a large group of sponge-associated microbes has been found to produce a specific family of communication signals called acyl-homoserine lactones (AHLs), known to regulate diverse processes including antibiotic synthesis, nutrient acquisition, and microbial gene exchange in other bacteria. AHLs are prime candidates for factors that shape the sponge community and facilitate coordination of microbial activities. This study will test the pervasiveness and importance of these signaling mechanisms for the well-characterized microbial communities of several shallow-water, tropical sponges. Advanced chemical, biochemical, molecular, microscopic and microbiological analyses will be applied to determine the extent to which these indigenous microorganisms communicate within the sponge, the functions under control of the signaling, and the connection to important attributes of the sponge, including production of novel metabolites.The study will provide broad insights into the ways that microbial communities proliferate and mature during host association, the regulation of microbial activity to promote symbiosis rather than disease, and the functional relationships between these microbes and the sponge. In a wider sense, this study will advance understanding of complex symbiotic processes and contribute to knowledge on signaling in interactions between bacteria and their hosts. This interdisciplinary project involves three different laboratories with different areas of expertise, and will train graduate students and postdoctoral researchers in ways that bridge the traditional areas of chemistry, ecology and molecular microbiology. Undergraduate student participation is also an important component of the study. In addition to undergraduate research assistants, the project also includes support for continuation of the successful Summer Microbiology and Research Training (SMaRT) course that offers a two week intensive laboratory research experience for minority students at the Center of Marine Biotechnology in Baltimore. This course provides students with a realistic research experience focused on sponge microbial communities, in close collaboration with the research scientists, postdoctoral researchers and graduate students.