Nitrogenase activity of Beijerinckia derxii is preserved under adverse conditions for its growth

Abstract

In order to evaluate the response of Beijerinckia derxii ICB-10 to different environmental factors, growth curves and specific nitrogenase activity were studied. Tested conditions were as follows: a) media with different pH values (2.5, 2.8, 4.2 and 5.7); b) medium supplemented with 230 µM aluminium sulphate; c) media with two different potassium phosphate concentrations (50 mM and 100 mM); d) shaken or still cultures; e) medium supplemented with 40 mM sodium thiosulphate. Growth curves and specific nitrogenase activity at pH 4.2 were closely similar to those for cultures at pH 5.7 (standard condition), whereas no growth occurred at pH 2.5. Changes in growth curves and/or specific nitrogenase activity were observed under the following conditions: I) pH 2.8 (decrease in initial CFU number, reduction of maximum specific growth rate, reduced number of generations and stimulation of nitrogenase activity), II) presence of aluminium (early death phase), III) 50 mM PO4 3-(reduction of maximum specific growth rate), IV) 100 mM PO4 3-(reduction of both number of generations and maximum specific growth rate as well as early death phase), V) low O2 availability (increasing nitrogenase activity), and VI) presence of thiosulphate (reduction of maximum specific growth rate; early death phase and high stimulation of nitrogenase activity). The data obtained showed the high variability of the cell growth response to environmental factors. Nitrogenase activity was always preserved even when population growth was affected.

Characterization of brown-black pigment isolated from soil bacteria,Beijerinckia fluminensis

“…In shaker conditions, the cells utilize growth nutrients faster and move early to the stationary phase, which results in the transition of older cells to stress conditions, leading to melanin production (Fig. 5) [10,11].…”

“…Barbosa et al [10] observed an increase in slime production and cell density in B. derxii over the time when glucose was the sole carbon source. Barbosa et al 2002, have also shown that co-factors like metal salts and aerobic conditions are essential for the cell growth and specific nitrogenase activity of B. derxii strain ICB-10 [11]. Becking, observed that Beijerinckia species grow in the pH range of 3.0 to 9.0 at an optimal temperature of 25 ° C to 30 ° C [12,13,14].…”

Atmospheric Nitrogen Fixing Capacity of Azotobacter Isolate from Cooch Behar and Jalpaiguri Districts Soil of West Bengal, India

“…Acid tolerant strains Beijerinckia derxii racts differently to aluminium. Barbosa et al, (2002) observed that a decline in the number of CFU was observed immediately after the end of the exponential phase.…”