title: The spatial organization and microbial community structure of an epilithic biofilm.
abstract: Microbial biofilms are common on lithic surfaces, including stone buildings. However, the ecology of these communities is poorly understood. Few studies have focused on the spatial characteristics of lithobiontic biofilms, despite the fact that spatial structure has been demonstrated to influence ecosystem function (and hence biodegradation) and community diversity. Furthermore, relatively few studies have utilized molecular techniques to characterize these communities, even though molecular methods have revealed unexpected microbial diversity in other habitats. This study investigated (1) the spatial structure and (2) the taxonomic composition of an epilithic biofilm using molecular techniques, namely amplicon pyrosequencing and terminal restriction fragment length polymorphism. Dispersion indices and Mantel correlograms were used to test for the presence of spatial structure in the biofilm. Diversity metrics and rank-abundance distributions (RADs) were also generated. The study revealed spatial structure on a centimetre scale in eukaryotic microbes (fungi and algae), but not the bacteria. Fungal and bacterial communities were highly diverse; algal communities much less so. The RADs were characterized by a distinctive 'hollow' (concave up) profile and long tails of rare taxa. These findings have implications for understanding the ecology of epilithic biofilms and the spatial heterogeneity of stone biodeterioration.
authors.affiliation: Geography Department, University of Cambridge, Downing Place, Cambridge CB2 3EN, UK nac37@cam.ac.uk.
authors.forename: Nick A
authors.initials: NA
authors.lastname: Cutler
authors.affiliation: Department of Mineral Sciences, Smithsonian Institution, National Museum of Natural History, 10 & Constitution NW, Washington, DC 20560-119, USA.
authors.forename: Dominique L
authors.initials: DL
authors.lastname: Chaput
authors.affiliation: Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire OX10 8BB, UK.
authors.forename: Anna E
authors.initials: AE
authors.lastname: Oliver
authors.affiliation: School of Geography and the Environment, Oxford University Centre for the Environment, South Parks Road, Oxford OX1 3QY, UK.
authors.forename: Heather A
authors.initials: HA
authors.lastname: Viles
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics; D018407:Bacterial Physiological Phenomena; D001483:Base Sequence; D001673:Biodegradation, Environmental; D018441:Biofilms / Q000145:classification*; D000460:Chlorophyta / Q000382:microbiology; D017753:Ecosystem; D005658:Fungi / Q000145:classification / Q000235:genetics / Q000502:physiology*; D064307:Microbiota / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA
keywords: TRFLP; amplicon pyrosequencing; bacteria; fungi; green algae; lithobiontic microbes; mantel correlograms; rank-abundance distributions