The long-term goal of this project is to determine how the model Gram-positive organism, Bacillus subtilis, decides to engage in single or social motility. The objective of this research is to study the differential expression of flagellar genes in swimming (single) and swarming (social) cells. The central hypothesis for the work is that differential expression of the clusters of flagellar genes in the B. subtilis chromosome enables the bacterium to elaborate either swimming or swarming motility. This hypothesis is based on preliminary findings that demonstrate that flagellar genes are clustered in B. subtilis and appear to be regulated differently. An understanding of social behaviors in bacteria is significant due to the increased recognition that social behaviors prevail in the natural environment. Currently, much of what is known about bacterial physiology is based on analysis of individual cell properties as they grow in the laboratory, instead of the analysis of their sophisticated behaviors in natural multicellular communities. Completion of the proposed research will generate basic scientific knowledge about the molecular control of single and social behaviors in B. subtilis, establishing this microbe as an important model for the study of multicellular processes in bacteria. The research will be undertaken at a minority-serving institution and 6-8 undergraduates and master's students trained in each year of the project, thereby promoting the connection between research and education, as well as increasing the diversity of the scientific workforce.
INTELLECTUAL MERIT As microbiologists we have tended to study the behaviors of individual bacteria. We have also assumed that the results obtained by studying one genetically identical bacterium are representative of all the genetically identical bacteria in the community. We now know this is not the case. Work in the last decade finds that genetically identical bacteria within a population of bacteria display different behaviors. These social behaviors are often cooperative, highly organized, and allow the bacteria to better survive in their natural environment where they live in communities. Nonetheless, much of what is known about bacterial physiology is based on analysis of individual cell properties as they grow in liquid medium in the research laboratory, instead of the analysis of their sophisticated behaviors in multicellular communities. For example, the PI and others have extensively studied the genetic control of swimming motility in the soil bacterium, Bacillus subtilis, but studies of the genetic systems that control multicellular swarming motility are relatively recent. Motility is the behavior that allows bacteria to move. Motility in liquid medium is called swimming and is controlled at the single-cell level in bacteria; whereas, motility across solid surfaces is called swarming and requires multicellular cooperation. Through NSF funding provided by this RUI grant we were able to study a strain of B. subtlis we created in the laboratory that could swim and swarm (see submitted image). Our studies generated basic scientific knowledge about how indvidual swimming and social swarming motility in B. subtilis is coordinated and controlled. Furthermore, we found evidence of population heterogeneity in genetically identical bacteria displaying swarming motility, further cementing support for this paradigm-shifting concept in microbiology. BROADER IMPACT A primary goal of the NSF RUI (Research at Undergraduate Institutions) grant is to provide hands-on research opportunities to undergraduate students who will become the nation’s scientific workforce. The PI of this grant is a research professor at San Francisco State University (SFSU). SFSU is a minority-serving institution that has been ranked #1 amongst the 529 Carnegie classified "master’s colleges and universities" in the number of its baccalaureate graduates that go on to pursue the doctorate in Biological Sciences (NSF 96-334). As a result of this award 8 undergraduates were trained, as well as 7 master’s students. Two of the master’s students were also undergraduates in the laboratory so that a total of 13 students were trained as an outcome of this award. Six of the eight undergraduates, and six of the seven master’s students were members of groups underrepresented in the sciences. Of the 13 students that were mentored through the course of this grant, 5 entered a Ph.D. program upon leaving the laboratory, another is applying to Ph.D. programs this year, 1 entered an M.D. program with 2 applying this year, 1 entered a Professional Science Masters program, 1 pursued a nursing degree, 1 is leading a science education outreach program, and 1 student withdrew from school due to serious medical illness. In summary, the training outcomes of this NIH RUI grant promoted the connection between research and education for students in the PI’s research laboratory and in her classes, as well as contributed to increasing the diversity of the scientific workforce that is tasked with serving the scientific, medical, and technological needs of our multi-ethnic nation.
