Effect of agitation and aeration on the production of nitrile hydratase by Rhodococcus erythropolis MTCC 1526 in a stirred tank reactor

Abstract

Aims: To evaluate the effect of different physicochemical parameters such as agitation, aeration and pH on the growth and nitrile hydratase production by Rhodococcus erythropolis MTCC 1526 in a stirred tank reactor. Methods and Results: Rhodococcus erythropolis MTCC 1526 was grown in 7‐l reactor at different agitation, aeration and controlled pH. The optimum conditions for batch cultivation in the reactor were an agitation rate of 200 rev min−1, aeration 0·5 v/v/m at controlled pH 8. In this condition, the increase in nitrile hydratase activity was almost threefold compared to that in the shake flask. Conclusion: Agitation and aeration rate affected the dissolved‐oxygen concentration in the reactor which in turn affected the growth and enzyme production. Significance and Impact of the Study: Cultivation of R. erythropolis MTCC 1526 in the reactor was found to have significant effect on the growth and nitrile hydratase production when compared to the shake flask.

A two-stage oxygen supply control strategy for enhancing milk-clotting enzyme production by Bacillus amyloliquefaciens

“…Kinetic analysis indicated that cell accumulation and MCA productivity were enhanced during the first 16 h at a K L a of 72.2 h -1 . It has been reported that sufficient oxygen supply is necessary for the synthesis of enzymes, nucleic acids, vitamins and other essential metabolites [22,23]. Therefore, higher availability of dissolved oxygen is favorable for high cell density accumulation and ultimately a high MCE yield.…”

Detoxification of Groundnut Cake Naturally Contaminated with Aflatoxin B1 Using Rhodococcus erythropolis in Shake Flask Bioreactors

“…Oxidative stress caused by excess oxygen and other oxides limits the growth of aerobic [33]. Oxidative and high-shear damage on R. erythropolis was also observed by Kamble and Meena [32] while increasing agitation speed from 200 to 300 rpm.…”

“…Rhodococcus erythropolis is known to be a flocculating agent for bioremediation processes [31]. However, flocculating activity of this organism negatively affects the growth rate by forming cell floccules and biofilms, reducing efficiency of aeration and agitation [32]. Furthermore, as the agitation speed was further increased, limitation in growth was observed.…”

Production of Nitrilase by a Recombinant Escherichia coli in a Laboratory Scale Bioreactor

“…Agitation rate is known to affect growth and enzyme production of some nitrilase producing bacteria [23]. Recombinant microorganisms can be particularly sensitive to the agitation regimen in a bioreactor [24].…”

“…Oxygen is vital for the growth of the aerobic organism, however, at higher aeration rate, enzyme activity may be adversely affected. This fermentation therefore required a relatively high oxygen transfer capability in the bioreactor, but not an excessively intense hydrodynamic shear environment [23].…”