Page 297 - Demo

SECTION II. APPLIED BIOTECHNOLOGY IN THE PHARMACEUTICAL INDUSTRY... 301This observation is consistent with Domsch et al. (1980) [10], who reported an optimal temperature range of 30 to 37 %u00b0C for various Monascus sp. isolates. An interesting observation from the study on pH influence is that the maximum absorbance at 500 nm recorded at pH 7 shifted to 400 nm (corresponding to yellow pigment) at pH levels of 6 and 8. At pH 8, the production of yellow pigments reaches its peak, surpassing pigment levels observed at pH 7. These findings align with those of Carvalho et al. (2005) [11], who also reported shifts in peak pigment absorbance at different incubation temperatures. In this study, we observed a significant change in the pH of the solid substrate after autoclaving (data not shown). The pH of the mineral solution was adjusted to the desired level and mixed with the substrate, but following autoclaving, the substrate pH decreased by 0.3 units. Studies by Babitha et al. (2007) [4] across a wide pH range, from 4.5 to 7.5, demonstrated varied pigment production with absorbance peaks around 410 nm and 510 nm. At pH 3, the maximum absorbance occurred at 469 nm, while at pH levels 3.5 and 4, the peak shifted leftward, with peak values at 445 and 400 nm, respectively. It has been reported that at lower pH levels, yellow pigments are predominant, whereas at higher pH levels, red pigments are more dominant [12]. These findings may hold significance, suggesting potential industrial applications for pigments produced on rice bran as robust food colorants.In solid-state fermentation (SSF), moisture content is a key parameter for controlling microbial growth and metabolite production [13]. The effect of the initial moisture content of the substrate is shown in Figure 4. Maximum pigment production was observed at an initial moisture level of 65% (15.12 OD units within 144 hours). Lower pigment yields were noted when the