Bennett Kapili

All Publications

• An Unusual Inverted Saline Microbial Mat Community in an Interdune Sabkha in the Rub' al Khali (the Empty Quarter), United Arab Emirates PLOS ONE McKay, C. P., Rask, J. C., Detweiler, A. M., Bebout, B. M., Everroad, R. C., Lee, J. Z., Chanton, J. P., Mayer, M. H., Caraballo, A. A., Kapili, B., Al-Awar, M., Al-Farraj, A. 2016; 11 (3)

  Abstract

  Salt flats (sabkha) are a recognized habitat for microbial life in desert environments and as analogs of habitats for possible life on Mars. Here we report on the physical setting and microbiology of interdune sabkhas among the large dunes in the Rub' al Khali (the Empty Quarter) in Liwa Oasis, United Arab Emirates. The salt flats, composed of gypsum and halite, are moistened by relatively fresh ground water. The result is a salinity gradient that is inverted compared to most salt flat communities with the hypersaline layer at the top and freshwater layers below. We describe and characterize a rich photosynthetically-based microbial ecosystem that is protected from the arid outside environment by a translucent salt crust. Gases collected from sediments under shallow ponds in the sabkha contain methane in concentrations as high as 3400 ppm. The salt crust could preserve biomarkers and other evidence for life in the salt after it dries out. Chloride-filled depressions have been identified on Mars and although surface flow of water is unlikely on Mars today, ground water is possible. Such a near surface system with modern groundwater flowing under ancient salt deposits could be present on Mars and could be accessed by surface rovers.

  View details for DOI 10.1371/journal.pone.0150342

  View details for Web of Science ID 000372574900036

  View details for PubMedID 26982497

• Vertical distribution of algal productivity in open pond raceways ALGAL RESEARCH-BIOMASS BIOFUELS AND BIOPRODUCTS Murphy, T. E., Kapili, B. J., Detweiler, A. M., Bebout, B. M., Prufert-Bebout, L. E. 2015; 11: 334-342

  View details for DOI 10.1016/j.algal.2015.07.003

  View details for Web of Science ID 000363046900040

• Heteromeric transposase elements: generators of genomic islands across diverse bacteria MOLECULAR MICROBIOLOGY Peters, J. E., Fricker, A. D., Kapili, B. J., Petassi, M. T. 2014; 93 (6): 1084-1092

  Abstract

  Horizontally acquired genetic information in bacterial chromosomes accumulates in blocks termed genomic islands. Tn7-like transposons form genomic islands at a programmed insertion site in bacterial chromosomes, attTn7. Transposition involves five transposon-encoded genes (tnsABCDE) including an atypical heteromeric transposase. One transposase subunit, TnsB, is from the large family of bacterial transposases, the second, TnsA, is related to endonucleases. A regulator protein, TnsC, functions with different target site selecting proteins to recognize different targets. TnsD directs transposition into attTn7, while TnsE encourages horizontal transmission by targeting mobile plasmids. Recent work suggests that distantly related elements with heteromeric transposases exist with alternate targeting pathways that also facilitate the formation of genomic islands. Tn6230 and related elements can be found at a single position in a gene of unknown function (yhiN) in various bacteria as well as in mobile plasmids. Another group we term Tn6022-like elements form pathogenicity islands in the Acinetobacter baumannii comM gene. We find that Tn6022-like elements also appear to have an uncharacterized mechanism for provoking internal transposition and deletion events that serve as a conduit for evolving new elements. As a group, heteromeric transposase elements utilize diverse target site selection mechanisms adapted to the spread and rearrangement of genomic islands.

  View details for DOI 10.1111/mmi.12740

  View details for Web of Science ID 000342757200002

  View details for PubMedID 25091064