Poles apart: Biodiversity and biogeography of sea ice bacteria

Citation
Jt. Staley et Jj. Gosink, Poles apart: Biodiversity and biogeography of sea ice bacteria, ANN R MICRO, 53, 1999, pp. 189-215
Citations number
84
Language
INGLESE
art.tipo
Review
Categorie Soggetti
Microbiology
Journal title
ANNUAL REVIEW OF MICROBIOLOGY
ISSN journal
0066-4227 → ACNP
Volume
53
Year of publication
1999
Pages
189 - 215
Database
ISI
SICI code
0066-4227(1999)53:<189:PABABO>2.0.ZU;2-T
Abstract
This review introduces the subjects of bacterial biodiversity and biogeogra phy. Studies of biogeography are important for understanding biodiversity, the occurrence of threatened species, and the ecological role of free-livin g and symbiotic prokaryotes. A set of postulates is proposed for biogeograp hy as a guide to determining whether prokaryotes are "cosmopolitan" (found in more than one geographic location on Earth) or candidate endemic species . The term "geovar" is coined to define a geographical variety of prokaryot e that is restricted to one area on Earth or one host species. This review discusses sea ice bacteriology as a test case for examining bacterial diver sity and biogeography. Approximately 7% of Earth's surface is covered by se a ice, which is colonized principally by psychrophilic microorganisms. This extensive community of microorganisms, referred to as the sea ice microbia l community (SIMCO), contains algae (mostly diatoms), protozoa, and bacteri a. Recent investigations indicate that the sea ice bacteria fall into four major phylogenetic groups: the proteobacteria, the Cytophaga-Flavobacterium -Bacteroides (CFB) group, and the high and low mol percent gram-positive ba cteria. Archaea associated with sea ice communities have also been reported . Several novel bacterial genera and species have been discovered, includin g Polaromonas, Polaribacter, Psychroflexus, Gelidibacter, and Octadecabacte r; many others await study. Some of the gram-negative sea ice bacteria have among the lowest maximum temperatures for growth known, < 10 degrees C for some strains. The polar sea ice environment is an ideal habitat for studyi ng microbial biogeography because of the dispersal issues involved. Dispers al between poles is problematic because of the long distances and the diffi culty of transporting psychrophilic bacteria across the equator. Studies to date indicate that members of some genera occur at both poles; however, co smopolitan species have not yet been discovered. Additional research on pol ar sea ice bacteria is needed to resolve this issue and extend our understa nding of its microbial diversity.