How can a photosynthetic bacterium help us understand a fundamental question in evolutionary biology? The acquisition and loss of genetic information permits the adaptation of an organism to an ever-changing environment. However, this genetic flux is a double-edged sword. On the one hand, it permits the acquisition of new adaptive traits, but this process may… [Read More]

Shotgun sequencing of a simple acid-mine-drainage biofilm community has recently demonstrated that, for one archaeal species population at least, individual genomes are recombinant mosaics (i.e., combinations of segments of genomes) of closely related strains. This suggests that, as in sexual organisms and contrary to current opinion, genetic exchange may be the cohesive force holding microbial… [Read More]

The overall goal of this project is to understand the genomic underpinnings of the observed ecological diversity and distribution of Prochlorococcus. This unicellular cyanobacterium is an extremely abundant primary producer in the world’s oceans, is the smallest known oxygenic phototroph, and has a compact genome (as small as 1.7 Mbp). Its abundance and phototrophic metabolism… [Read More]

Iron is the most abundant redox-active element in the solar system and the second most abundant redox-active element in Earth’s crust. The capacity for iron oxidation is broadly distributed among prokaryotes, and the activities of iron-oxidizing bacteria exert critical influence on many major elemental cycles, including the carbon cycle. Despite its importance, the fundamental biology… [Read More]

Earth’s microbiota is remarkably pervasive, thriving at extremely high temperature, low and high pH, high salinity, and low water availability. One major evolutionary lineage of microbial life, the Archaea, is especially adept at exploiting environmental extremes. Despite their success in these challenging habitats, the Archaea may now also be viewed as cosmopolitan. Archaea are now… [Read More]

In contrast to many other marine invertebrates that generally harbor only a single bacterial symbiont, gutless oligochaetes are unique in having established highly specific and stable associations with multiple endosymbiotic species. These small worms have completely reduced their digestive and excretory systems and live in obligate symbiosis with phylogenetically diverse co-occurring bacterial symbionts. This project… [Read More]

It is a disturbing reality that we have only fragmentary understanding of the enormous microbial diversity that exists on our planet. This applies not merely to microbes living in extreme environments, which would be expected to possess unusual and perhaps not yet fully characterized properties, but also to those microbes in more mundane habitats, like… [Read More]

The hyperthermophile genus Pyrobaculum represents a unique clade among the archaea because its cultured members respire toxic metals such as arsenic and selenium, sulfur compounds, ferric (Fe(III)) iron, nitrate, and oxygen. Pyrobaculum species are also capable of chemolithotrophic and organotrophic growth. In contrast to the emerging crenarchaeal model Sulfolobus, which is an acidophilic obligate aerobe,… [Read More]

Every year, enormous amounts of high-strength terephthalate-containing wastewater are produced as a byproduct of the plastics industry. The wastewater is currently treated by using anaerobic biological treatment processes that involve mesophilic (moderate-temperature-loving) microbes growing at 35-37°C. Recently, a thermophilic (heating-loving) terephthalate-degrading community growing at around 55°C has been developed in a lab-scale bioreactor as a… [Read More]