Furfural and hydroxymethylfurfural inhibition of growth and photosynthesisin spirulina

Abstract

Growth of the cyanobacteria Spirulina maxima, S. platensis and S. laxissima was stopped by 7 mM of furfural. Photosynthetic oxygen evolution was instantly inhibited when 50 mM of furfural was added, whereas 7 mM inhibited oxygen evolution only when the cells were preincubated with this compound for more than 5 h. Furfural did not inhibit methyl viologen- supported photosynthetic oxygen uptake. Electron transfer from diphenylcarbazide (DPC) to 2,6-dichlorophenolindophenol (DCPIP) in isolated thylakoids was also unaffected by the presence of this chemical. The inhibition by furfural of C02-dependent oxygen evolution could be partially reversed by the subsequent addition of the oxidized form of p-phenylenedia- mine (PDox). However, longer preincubation with furfural decreased the oxygen uptake rate and (PDox)dependent Hill reaction rate. Thus, the electron transfer from the acceptor side of Photosystem-I to C02is more susceptible to furfural inhibition than is that from water to Photosystem-I. Hydroxymethylfurfural had the same effects as furfural but was less toxic. © 1990 The British Phycological Society.