Aims: The synergistic bio-activity between oleaginous yeast and microalga has been recognized, which would enhance lipid production as biodiesel feedstock. Nevertheless, yeast and microalga require different conditions for optimal growth. In this study, the locally isolated oleaginous yeast Rhodotorula toruloides and microalga Chaetoceros muelleri were co-cultivated to enhance biomass and lipid production. Methodology and results: The growth characteristics of both yeast and microalga monocultures were initially determined prior to optimizing the co-cultivation conditions. The biomass and lipid productivity of the co-culture were investigated and compared to their monocultures. The results showed that R. toruloides grew actively within 3 days while C. muelleri exhibited more prolonged cultivation, up to 21 days. The co-cultivation could be carried out optimally using growth media at pH 6, light intensity of 15,000 lux and yeast/microalga ratio of 1:2, yielding the highest biomass productivity determined at 0.18 g/l/day and lipid production of 17%. The lipid productivity of the co-culture increased by 42% and 75% as compared to monocultures of yeast and microalga, respectively. Furthermore, the biomass productivity was also higher than the monoculture, about 1.2-fold for the yeast and 13-fold for the microalga. Conclusion, significance and impact of study The findings revealed that co-cultivation of yeast and microalga is a viable technique for long-term microbial oil production.

Aims: This study investigates the potential of porous polymethacrylate monoliths as enzyme support materials for large-scale enzyme commercialization. Methodology and results: It focuses on their preparation and various immobilization techniques, such as adsorption, covalent-binding and cross-linking, specifically applied to β-galactosidase for bioprocess applications. The research assesses immobilization performance, operational stability, reusability and optimization using response surface methodology (RSM). The results reveal that covalent-binding exhibited the highest enzyme activity recovery, while cross-linking showed superior performance at lower enzyme concentrations but decreased at higher concentrations. Covalent-bound enzymes demonstrated reusability for up to four cycles, with optimal pH ranging between 7 and 8 and optimal temperature ranging between 30 °C and 40 °C. Furthermore, RSM optimization highlighted the significant influence of substrate concentration on enzyme activity, with a reliable model (R2 = 0.9163) and adequate precision (S/N = 13.1409). Conclusion, significance and impact of study Overall, this study provides valuable guidelines for effectively employing porous monoliths in large-scale industrial bioprocessing, offering potential cost-saving benefits and enhanced efficiency in enzyme commercialization.