Page 290 - Demo

294 PROCEEDINGS OF INTERNATIONAL SCIENTIFIC CONFERENCE ON APPLIED BIOTECHNOLOGY2.4. Effect of different incubation periods on pigment productionProduction of red pigment by M. purpureus HG12 was investigated in rice bran, the best solid substrate for red pigment production. Sterilized flasks were cooled, inoculated and incubated at 30%u00b0C in static conditions. The pigment was estimated 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, and 22 days after inoculation. 2.5. Effect of different moisture content on pigment production A range of 45, 55, 65, 75 and 85% moisture content were prepared [6]. Effect of different moistening agents on pigment production. The tested moistening agents were tap water, distilled water and mineral salt solution. 2.6. Effect of different pH on pigment productionThe effect of pH on pigment production on solid substrate was studied by using pH values 4.0 to 9.0 on mineral salt solution.2.7. Antibacterial ability of pigment extract from Monascus purpureus HG12The test strains, including Escherichia coli ATCC 11105, Salmonella typhimurium ATCC 14028, Staphylococcus aureusATCC 25923, and Bacillus subtilis ATCC 6633, were supplied by the Fermentation Technology Laboratory of the Institute of Biotechnology. The pigment of strain H12 was dissolved in a 10% DMSO solution. In this experiment, controls included a negative control (DMSO) and a positive control (tetracycline at 30 %u03bcg/mL). For each test, 100 %u03bcL of the test solution was added to a well in the agar plate, and the petri dishes were incubated for 24 hours at 37%u00b0C. Following incubation, the diameter of the inhibition zone was measured. The presence of an inhibition zone indicated that the test solution exhibited antibacterial activity against the tested bacterial strain [8].