text: The main advantage of FbFPs over GFP is their independence of molecular oxygen. Since all GFP derivatives and homologues require molecular oxygen for the maturation of their chromophore, these fluorescent proteins are of limited use under anaerobic or hypoxic conditions. 
  Since FbFPs bind FMN as chromophore, which is synthesized independently of molecular oxygen, their fluorescence signal does not differ between aerobic and anaerobic conditions.<br />
  Another advantage is the small size of FbFPs, which is typically between 100 and 150 amino acids. This is about half the size of GFP (238 amino acids). It could for example be shown that this renders them superior tags for monitoring tobacco mosaic virus infections in tobacco leaves.<br />
  Due to their extraordinary long average fluorescence lifetime of up to 5.7 ns they are also very well suited for the use as donor domains in FRET systems in conjunction with e.g. YFP (see photophysical properties). A fusion of EcFbFP and YFP was e.g. used to develop the first genetically encoded fluorescence biosensor for oxygen (FluBO)
  The main disadvantage compared to GFP variants is their lower brightness (the product of ε and Φ). The commonly used EGFP (ε = 55,000 Mcm; Φ = 0.60 ) for example is approximately five times as bright as EcFbFP.<br />
  Another disadvantage of the FbFPs is the lack of color variants to tag and distinguish multiple proteins in a single cell or tissue. The largest spectral shift reported for FbFPs so far is 10 nm. Although this variant (Pp2FbFP Q116V) can be visually distinguished from the others with the human eye, the spectral differences are too small for fluorescence microscopy filters.