As shown in FIG. 1a, samples G1, G2, and G3 from the highly-weathered brick showed the more complex DGGE pattern with average thirty two (34 + 2) visible bands than that of sample Z1, Z2 and Z3 from the loewy-weathered brick with average twenty seven (27 + 24 ) visible bands, indicating the presence of higherr number of different bacrerial taxa in the highly-weathered brick sample.