Growth and consumption of glucose by mutant 32 was studied at 20 as well as 30 °C (Figure 3.3, Figure 3.4). At 20 °C, during logarithmic phase, maximum specific growth and glucose utilization rate were 0.26 h-1 and 0.92 ±0.1 g/l/h, respectively, which were lesser than that at 30 °C (0.4 h-1, 0.43 ±0.1 g/l/h) as expected. There was no major difference observed in the final dry cell mass (31.75 ±0.25 g/l) at both temperatures. At 20 °C, maximum specific carotenoid production obtained was between 24-28 h (0.975 mg/g/h). β-Carotene accounted for more than 90% (w/w) of total carotenoids during fermentation run, maximum being 95 ±0.5% (w/w) between 36 to 40 h (Figure 3.5). At the end of the fermentation (90 h) β-carotene, torulene and torularhodin were in the proportion of 90, 8, and 2%, respectively, of the total carotenoid content (11.03 ±0.73 mg/g, 277 ±7 mg/l).
Figure 3.3 Effect of temperature on Rhodotorula glutinis mutant 32 during batch cultivation at 20 °C (ο) and 30 °C (g). Under similar conditions at 30 °C, maximum specific carotenoid production was found to be 0.46 mg/g/h during 40-44 h. β-Carotene was the major carotenoid produced but substantial amount of torulene was also produced, simultaneously. At the end of the fermentation (88 h), β-carotene, torulene and torularhodin were present in the
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