We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Substrate Optimization for PHB Production from Ricotta Cheese Exhausted Whey Using Azohydromonas lata DSM 1123
Summary
Researchers used ricotta cheese whey — a high-volume dairy byproduct — as a low-cost substrate to produce polyhydroxybutyrate, a biodegradable bioplastic, using the bacterium Azohydromonas lata. By supplementing with minerals, optimizing nitrogen ratios, and using enzyme-assisted lactose digestion, the team achieved up to 32.74% intracellular PHB accumulation in flask cultures and improved yields further in bioreactor fed-batch trials.
Valorization of ricotta cheese exhausted whey (RCEW), a dairy by-product generated in large quantities worldwide, is essential to mitigate its environmental impact and unlock its economic potential. This study explores the use of RCEW as a substrate for polyhydroxyalkanoate (PHA) production by Azohydromonas lata DSM 1123. The substrate was characterized by low protein and fat contents and a relevant lactose concentration (3.81%, w/v). Due to A. lata's inability to directly metabolize lactose, β-galactosidase supplementation was necessary. Mineral supplementation of pasteurized RCEW significantly improved both microbial biomass and PHA synthesis, achieving up to 25.94% intracellular PHA content, whereas pre-adaptation trials failed to enhance strain performance. Moderate nitrogen limitation in the substrate (C/N ratio 44) favored PHA synthesis (0.55 g/L) and 32.74% intracellular accumulation. Thermal treatments decreased initial microbial contamination, hence a balanced mixture of pasteurized-sterilized (75:25) substrate was used to modulate RCEW protein content without the inclusion of additional technological or chemical processing steps and without lactose loss or dilution. Bioreactor trials using optimized RCEW pre-treatment conditions led to a further increase in biomass (2.36 g/L) and PHA production (0.88 g/L), especially under fed-batch conditions. The extracted polymer was confirmed to be polyhydroxybutyrate (PHB), with high thermal stability and a molecular weight of 5.9 KDa.