Microbial Diversity: Its Exploration and Need of Conservation - Applied Environmental Biotechnology: Present Scenario and Future Trends - page 50

Fig. 4.2 DGGE: PCR products of mixed communities
are loaded on a gel with a gradient of denaturant (typi-
cally 20-80 % formamide). Double stranded DNA will

run down the gel until it melts. Melting is determined by
sequence and GC content. Different sequences migrate
different distances ( a ), You obtain a “barcode” of the com-
munity ( b )

organisms that could be maintained in culture
along with those that cannot be cultured. Those
uncultivable microorganisms cannot be identi-
fied by standard means. Pace, for example, ex-
tracted DNA directly from samples, then used

the polymerase chain reaction (PCR) to amplify
small subunit ribosomal RNA (rRNA) genes, se-
lectively amplifying those found in archaea and
eukaryotes.