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

海洋海绵已被证明是抗癌药物和抗生素等新药的丰富来源。这些简单的动物还拥有大量稳定的共生微生物，这些微生物通常是药用活性化合物的来源。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，包括获取有限的营养物质和防止有害疾病病原体。海绵中的微生物群落是复杂而多样的，代表了许多不同类型的微生物，它们具有广泛的能力。与大多数复杂的微生物群落一样，人们对海绵中微生物群的建立和稳定的因素和机制几乎一无所知。对于海洋海绵来说，面对周围大量含微生物的海水，如何引入和维持特定的微生物，以及如何在海绵组织内培养不同微生物的适当平衡，目前还不清楚。细菌协调其活动的一种机制是通过交换化学信号。近年来，人们已经清楚地认识到，许多细菌可以通过不同的化学语言“交谈”，这种微生物间的对话可以对微生物群落的功能产生重大影响。在一个相关的NSF微生物观测项目中，一大批与海绵相关的微生物被发现产生一种特殊的通信信号家族，称为酰基-高丝氨酸内酯（AHLs），已知可以调节多种过程，包括抗生素合成、营养获取和其他细菌的微生物基因交换。ahl是塑造海绵群落和促进微生物活动协调的主要候选因子。本研究将测试这些信号机制对几种浅水热带海绵微生物群落的普遍性和重要性。先进的化学、生化、分子、显微镜和微生物分析将被应用于确定这些本地微生物在海绵内交流的程度，信号控制下的功能，以及与海绵重要属性的联系，包括新代谢物的产生。该研究将为微生物群落在宿主关联过程中增殖和成熟的方式、微生物活动的调节以促进共生而不是疾病，以及这些微生物与海绵之间的功能关系提供广泛的见解。从更广泛的意义上说，这项研究将促进对复杂共生过程的理解，并有助于了解细菌与宿主之间相互作用的信号。这个跨学科项目涉及三个不同的实验室，拥有不同的专业领域，并将以连接化学、生态学和分子微生物学等传统领域的方式培养研究生和博士后研究人员。大学生参与也是本研究的重要组成部分。除了本科生研究助理之外，该项目还包括对成功的夏季微生物学和研究培训（SMaRT）课程的继续支持，该课程为巴尔的摩海洋生物技术中心的少数民族学生提供为期两周的强化实验室研究经验。本课程为学生提供了一个真实的研究经验，重点是海绵微生物群落，与研究科学家，博士后研究人员和研究生密切合作。

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.