Journal
APPLIED AND ENVIRONMENTAL MICROBIOLOGY
Volume 71, Issue 12, Pages 7806-7818Publisher
AMER SOC MICROBIOLOGY
DOI: 10.1128/AEM.71.12.7806-7818.2005
Keywords
-
Categories
Ask authors/readers for more resources
The abundant microbial population in a 3,043-m-deep Greenland glacier ice core was dominated by ultrasmall cells (< 0.1 mu m(3)) that may represent intrinsically small organisms or starved, minute forms of normal-sized microbes. In order to examine their diversity and obtain isolates, we enriched for ultrasmall psychrophiles by filtering melted ice through filters with different pore sizes, inoculating anaerobic low-nutrient liquid media, and performing successive rounds of filtrations and recultivations at 5 degrees C. Melted ice filtrates, cultures, and isolates were analyzed by scanning electron microscopy, flow cytometry, cultivation, and molecular methods. The results confirmed that numerous cells passed through 0.4-mu m, 0.2-mu m, and even 0.1-mu m filters. Interestingly, filtration increased cell culturability from the melted ice, yielding many isolates related to high-G+C gram-positive bacteria. Comparisons between parallel filtered and nonfiltered cultures showed that (i) the proportion of 0.2-mu m-filterable cells was higher in the filtered cultures after short incubations but this difference diminished after several months, (ii) more isolates were obtained from filtered (1,290 isolates) than from nonfiltered (447 isolates) cultures, and (iii) the filtration and liquid medium cultivation increased isolate diversity (Proteobacteria; Cytophaga-Flavobacteria-Bacteroides; high-G+C gram-positive; and spore-forming, low-G+C gram-positive bacteria). Many isolates maintained their small cell sizes after recultivation and were phylogenetically novel or related to other ultramicrobacteria. Our filtration-cultivation procedure, combined with long incubations, enriched for novel ultrasmall-cell isolates, which is useful for studies of their metabolic properties and mechanisms for long-term survival under extreme conditions.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available