Studies on poly-β-hydroxybutyrate synthase activity of Nostoc muscorum

The Journal of General and Applied Microbiology

Akhilesh Kumar Singh¹  Nirupama Mallick¹  Bhabatarini Panda¹  Laxuman Sharma¹ 

[1] Agricultural and Food Engineering Department, Indian Institute of Technology

关键词: acetyl phosphate;    chemoheterotrophy;    Nostoc muscorum;    PHB synthase;    poly-β-hydroxybutyrate;   

DOI  :  10.2323/jgam.52.209

学科分类：微生物学和免疫学

来源: Applied Microbiology, Molecular and Cellulrar Biosciences Research Foundation

【 摘 要 】

This study compares the PHB synthase activity of Nostoc muscorum, a N2-fixing cyanobacterium under control (grown in usual BG-11 medium), nitrogen (N) and phosphorus (P) deprivation and chemoheterotrophic conditions. Specific activity of PHB synthase did not depict significant variations in the latter three types of cultures, except for the control one, where a significantly lower activity was recorded. PHB synthase activity was detected only in the soluble fractions of both the control as well as cells incubated under chemoheterotrophic conditions. A Km of 80.2μM DL-β-hydroxybutyryl-CoA and Vmax of 197.5 nmol thiobenzoate (TNB) mg protein−1min−1 were observed for the enzyme. PHB synthase remained insensitive to acetyl-CoA, ATP, NADP, NADPH supplementation under in vitro condition. Addition of acetyl phosphate was found to activate the enzyme and the level of activation was dependent on the concentration of acetyl phosphate supplementation. Inhibition of PHB synthase in 2,3-butanedione supplemented cultures and reactivation following acetyl phosphate addition proved the post-translational control of acetyl phosphate over PHB synthase.

【 授权许可】

Unknown