MBIO 3280 Lecture Notes - Lecture 25: 16S Ribosomal Rna, Cytophaga, Habitat
17 Nov 2017
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Document Summary
Rare extremely unusual habitat for studying microbes. Can not sample lake water without contaminating drill on the way. Accreted ice (from lake) above lake vostok collected as ice cored (depth around 3358. Microscopy of meltwater from 3534-3611 m shows microbial density (range 200-1000 cells/ml) greatest in layers of ice with most particles. 16s rdna from samples determine identity and diversity found alpha and beta proteobacteria, cytophaga, gram + cultured bacteria from 3593m. 14c-labelled glucose or acetate converted to 14co2 demonstrates heterotrophic activity. Negative microbial associations with plants and animals fungal symbioses. Cell association more common than individual life. Heterocysts: fimbriae and pili (temporary, glued together after cell division (polysaccharides, polysaccharide capsule keeps their ecm close together. Aggregation has physical benefits: better adherence to soild surfaces, less susceptible to shearing forces in water (persistence in optimal microhabitat) ex. Biofilms: trapping of organic particles, very large aggregates can inhibit predators. Magnitude of a process influenced by population density.
