Vol. 9, Issue 1, Part F (2025)

This study explores the optimization of pullulan production by Aureobasidium pullulans under various fermentation conditions. The impact of various fermentation parameters, such as temperature, pH, inoculum size, carbon, and nitrogen sources, was systematically evaluated. The optimal temperature for pullulan production was found to be 28 °C, with a marked decrease in yield at higher temperatures due to thermal stress. The optimal pH was determined to be 5, with significant reductions in pullulan yield observed at both acidic and alkaline extremes. Inoculum size experiments revealed that a 1.5% inoculum resulted in the highest pullulan production, while larger inoculum sizes caused overcrowding effects, reducing yields. Among the carbon sources tested, glucose was the most effective, leading to the highest pullulan production. Yeast extract was identified as the most favourable nitrogen source, with a concentration of 0.5% optimizing pullulan synthesis. The time course of pullulan production revealed a peak yield of 7.850 g/L on Day 7 (168 hours), after which a decline in production was noted, likely due to nutrient depletion and accumulation of metabolic by-products. Sugar utilization patterns also demonstrated near-complete consumption by 168 hours, marking the end of optimal fermentation conditions. These findings provide valuable insights into the key parameters for optimizing pullulan production, contributing to enhanced yields and more efficient industrial-scale biopolymer production.