Effect of light conditions on phycoerythrin accumulation by thermophilic cyanobacterium Leptothermofonsia sichuanensis and characterization of pigment stability.

Phycoerythrin (C-PE) is a cyanobacterial phycobiliprotein with extensive applications. This work sought to investigate the effects of various light conditions on C-PE accumulation by thermophilic Leptothermofonsia sichuanensis and characterize its C-PE stability and purity. Accumulation of C-PE as the predominant phycobiliprotein was significantly affected by light regime and light colours, reaching the highest C-PE accumulation (21.92 mg/g) under blue light. Importantly, the results suggested the superior C-PE thermostability of Leptothermofonsia than the mesophilic counterparts and good pH stability at a range of 4 to 7. Additionally, C-PE indicated advantageous potential for preservation as revealed by photostability experiments. Moreover, sorbitol, sucrose, and NaCl can further stabilise C-PE at 60 °C, of which 10 % sorbitol is the most effective. The extraction process herein resulted in a C-PE purity of 2.68, much higher than the food grade. Collectively, this work demonstrates the Leptothermofonsia strain as a promising bioresource for thermostable C-PE production.