GROWTH YIELDS AND GLUCOSE METABOLISM OF N2-FIXING GLUCONACETOBACTER DIAZOTROPHICUS AT DIFERENT CULTURE PH VALUES

LUNA MARÍA F.; BOIARDI JOSÉ L.

WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY

SPRINGER

Lugar: AMSTERDAM; Año: 2008 vol. 24 p. 587 - 590

0959-3993

Abstract Gluconacetobacter diazotrophicus was grown in chemostat under N2-fixing conditions at different culture pH values (from 2.5 to 7.5) with glucose as the C-source. Maximum glucose and oxygen utilization yields were observed at pH values between 5.0 and 6.5. Yields, although lower, were not severely affected at acidic (2.5–4.5) and moderate alkaline (7.5) pH values. But, at pH values just over 7.5, cultures became unstable and washed out. Maximum biomass yields coincided with optimal activity (and minimal synthesis) of pyrroloquinoline quinone (PQQ)-linked glucose dehydrogenase (PQQ-GDH). At external pH values of 7.0 and above, whereas PQQGDH was actively synthesized, a very low in situ activity could be detected. The lack of PQQ-GDH activity at moderate alkaline pH values seems to be the cause of lack of growth of this organism under these conditions.