Long term diazotrophic cultivation induces phycobiliprotein production in Anabaena variabilis IMU8

Cyanobacteria are considered as a sustainable feedstock for the production of biochemically active compounds such as phycobiliproteins(PBPs).In this study,the impact of nitrogen(N)and phosphorus(P)availability on PBP production of“N-free acclimated”Anabaena variabilis IMU8 was analyzed.Upon isolation and identification,the cyanobacterium has been maintained in N-free BG-11 medium for more than 20 months.For experimentation,the strain was incubated in N-replete,N-depleted,N-P-depleted BG-11 medium.Long-term diazotrophic cultivation of A.variabilis IMU8 resulted in elevated PBP productivity with a limited impact on growth.When compared to N-depleted ones,N supply stimulated a slight induction of growth and total saccharide production,but total protein content did not change while PBP production decreased.On the other hand,N-P-depletion resulted in decreased growth rate along with reduced total protein and PBP production while rapid induction of total saccharide production was recorded.Fourier transform infrared spectroscopy results refer that membrane-bound oligosaccharides may have regulatory roles for PBP production in A.variabilis IMU8 during long term diazotrophic cultivation.