BIOLOGY 2EE3 Lecture Notes - Lecture 11: Winogradsky Column, Activated Sludge, Extracellular Polymeric Substance
Document Summary
Number of culturable microbes is very low. Conditions can change in microenvironments over short distances. Success of microbes in niches depends on ability to obtain nutrients to produce energy and biomass. Groups/layers of microbes on a surface that interact with and support each other. Also of practical importance to humans who want to rid a surface of microbes. A winogradsky column illustrates enrichment in action. Different microbes flourish in different areas of the column that correspond to different nutritional microenvironments. Cultivation-independent techniques: direct sequencing (without growth or cloning, extract dna and pcr (often for ssu rrna genes) sequence, compare to databases of known sequences for identification. Fluorescent in situ hybridization (fish: labeled oligonucleotide probes bind to specific dna/rna in a mixed population of cells visualize the cells under the microscope. Contain random dna fragments cloned into plasmids. Can be used to isolate genes without ever identifying the organism that actually encodes the gene.