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302 PROCEEDINGS OF INTERNATIONAL SCIENTIFIC CONFERENCE ON APPLIED BIOTECHNOLOGYmoisture level was either above or below this optimum. This result aligns with findings from Babitha et al. (2007) [4], who reported that substrates with an initial moisture content below 40% yielded less pigment, while levels between 50%u201356% resulted in the highest pigment production. Higher initial moisture content in SSF led to suboptimal product formation due to reduced mass transfer, whereas lower initial moisture levels resulted in diminished production.The antibacterial activity of the extract from M. purpureusHG12 has shown effectiveness against several pathogenic bacteria such as E. coli, S. typhimurium, S. aureus, and B. subtilis, with varying inhibition zone diameters (Table 3). This suggests that M. purpureus HG12 pigments possess bioactive compounds capable of exerting antimicrobial action, potentially useful in developing natural antibacterial agents. Further research could explore optimal extraction methods and conditions to maximize the antimicrobial potential of these pigment compounds.5. CONCLUSIONSThis study highlights the significant impact of temperature, pH, moisture content, and fermentation parameters on pigment production and the antimicrobial activity of Monascus purpureusHG12. The optimal conditions for pigment synthesis were identified as 30 %u00b0C, pH 7, and an initial substrate moisture content of 65%, with pigment production peaking after 18 days of incubation. Notably, pH influenced pigment characteristics, with red pigments predominating at neutral pH and yellow pigments increasing at alkaline pH levels, offering potential applications for industrial food colorants. The pigment extract from M. purpureusHG12 demonstrated antibacterial activity against bacterial pathogen as E. coli, S. typhimurium, and S. aureus, suggesting the presence of bioactive compounds with antimicrobial properties.