Roberto Kolter

Early life and education

Kolter was born and raised in Guatemala and received his bachelor's degree from Carnegie Mellon University. He then obtained his Ph.D. from the University of California, San Diego and completed post-doctoral training at Stanford University.

Research

During the 35-year term of the Kolter Laboratory at Harvard Medical School, more than 120 graduate student and postdoc trainees have explored an eclectic mix of topics gravitating around the study of microbes. In the 1990s, Kolter's research group was among the first to study the genetics of bacteria adhered to surfaces, living within communities called biofilms, and to consider biofilms as developmental and multicellular forms of microbes. The lab has discovered basic communication pathways underpinning biofilm development and characterized materials within the extracellular matrix of biofilms using model bacterial species like Pseudomonas aeruginosa and Bacillus subtilis. Kolter's lab also published early studies of cellular differentiation and division of labor in the context of multicellular microbial communities. In addition to biofilm biology, his group has done extensive work on basic bacterial physiology, intra and interspecies communication, microbial evolution, microbiome ecology, and bioactive compound discovery.

Kolter has co-authored over 240 research and other scholarly articles which have been cited over 42,000 times in total. Some of his major scientific contributions are listed below.

Regulation of DNA replication

As a graduate student, Kolter's research provided early evidence for what was then called the "replicon hypothesis," proposed by Jacob, Brenner and Cuzin in 1962. His work defined an origin of DNA replication that led to the development of many suicide cloning vectors still in use today.

Peptide antibiotic biosynthesis

As a faculty member at Harvard Medical school in the 1980s, Kolter's research group made use of Escherichia coli as a model organism for understanding the molecular genetics of antibiotic biosynthesis. During the course of this work the group was among the first to characterize ABC transporters, today known to be one of the most important membrane protein systems that move molecules across the cell membrane.

Physiology and evolution during stationary phase

In the late 1980s, Kolter's research group became interested in bacteria living in the stationary phase of the growth cycle, a state more like the natural conditions that bacteria experience in environments outside of the laboratory. The group discovered regulatory systems exclusive to cells in this non-growing state and found that mutants with greater fitness in stationary phase evolved and rapidly took over the cultures. This was one of the first examples of evolution occurring in the laboratory, or the now popular field of experimental evolution.

Bacterial biofilms

In the 1990s, Kolter's group became interested in the genetic pathways of surface-associated communities of bacteria called biofilms. Before then, biofilms had been discovered and were studied in the context of biofouling and in engineering solutions to prevent biofouling, but the genetics of biofilm formation was unexplored and most microbiologists did not view biofilm formation as a physiological process of bacterial cells. Due to work in the Kolter Lab and many other labs, microbial biofilms have since become a major field of microbiology, recognized for their importance as a predominant lifestyle of microbes in nature, of particular relevance in medicine, since many pathogenic bacteria rely on the biofilm state during infection.

Microbial intraspecies interactions, cell differentiation & division of labor

Another body of research stemmed from work on biofilms in the Kolter group in collaboration with the laboratory of Richard Losick: the discovery that subpopulations of different functional cell types develop within single-species biofilms of the bacterium Bacillus subtilis. Some cells were found to express genes for motility, others for sporulation, cannibalism, surfactant production or the secretion of extracellular matrix. Some cell types were found localized in clusters in different physical locations and time points during biofilm development. Another study from the group in 2015 showed that collective behaviors like group migration across a surface can emerge due to interactions between multiple cell types.

Microbial interspecies interactions

Much of Kolter's recent work has focused on interactions between several species in mixed communities, as they typically exist in natural environments. This work has produced several influential studies of the emergent properties and social behaviors of microbes while interacting with other species.

Books

Communication of microbiology to the public

Kolter is an advocate and participant in the communication of microbial science to non-scientific audiences. Kolter helps organize a lecture in Cambridge, Massachusetts open to the public each year through the Harvard Microbial Sciences Initiative, on topics of general relevance, such as the microbes that make foods like cheese and beverages like sake and wine. The Kolter Lab is also leading the development of two exhibitions at the Harvard Museum of Natural History in 2017, World in a Drop: Photographic Explorations of Microbial Life, opening in August 2017 and Microbial Life: A Universe at the Edge of Sight, opening in February 2018.

Teaching and editing

Kolter has a long record of teaching both at Harvard and at international summer courses. At Harvard he teaches Biofilm Dynamics and is developing a Massive Open Online Course (MOOC) with HarvardX. He is a regular instructor at the Microbial Diversity Course in Woods Hole, Massachusetts, the EMBO-FEBES summer microbiology course in Spetses, Greece and the John Innes/Rudjer Bošković Summer Schools in Applied Molecular Microbiology in Dubrovnik, Croatia. In 2000, he received the ASM International Professorship Award.

Kolter has been the cover editor of the Journal of Bacteriology since 1999, has served as a member of the Board of Reviewing Editors for Science Magazine, mBio, and eLife, and is an Associate Editor for npj Biofilms and Microbiomes.