Original paper
Fermentation in symbiotic and free-living Cyanobacteria
De Philippis, Roberto; Margheri, Maria Cristina; Vincenzini, Massimo
Algological Studies/Archiv für Hydrobiologie, Supplement Volumes No. 83 (1996), p. 459 - 468
19 references
published: Dec 19, 1996
DOI: 10.1127/algol_stud/83/1996/459
ArtNo. ESP142011700032, Price: 29.00 €
Abstract
Dark anaerobic metabolism was investigated in 13 axenic cyanobacterial strains, either symbiotic or free-living in the soil and belonging to the genera Nostoc (nine strains) and Anabaena (three strains of A. azollae and one of A. siamensis). Both symbiotic and freeliving strains were able to use exogenous sugars during anaerobic incubation in the dark. For most of them the fermentative metabolism supported maintenance processes rather than growth. Fermentation products always included acetate and, in most cases, low amounts of CO2 and H2. In two strains, acetate carbon accounted for almost all of the sugar carbon taken up, suggesting the existence of a homoacetic fermentative pathway. In nine strains, some lactate was also produced, in molar ratio with acetate ranging from 0.07 to 0.37; one strain produced formate instead of lactate. Ethanol was never detected. The fermentative metabolism of the strains, with one exception, did not change when they were incubated without any added sugar under the same culture conditions. The results demonstrate that, under dark anoxic conditions, exogenous carbohydrates as well as endogenous carbon reserves are degraded by this group of heterocystous cyanobacterial strains to give, as a consequence of an unpredictable metabolic diversity, different amounts and proportions of fermentation products.
Keywords
Heterocystous cyanobacteria • cyanophytes • Nostoc • Anabaena • cyanobacterial symbiosis • fermentation • dark-anaerobic metabolism • acetate • lactate • formate